Will: This is the Green Roof Podcast, Episode 4. Hi everyone, welcome to the Green Roof Podcast, the podcast dedicated to helping you getting you get your home or business on the road to a beautiful, energy-saving, living roof, even if you’re just starting today. My name is Will Ward.

Kevin: And this is Kevin Songer from sunny Florida.

Will: Today on the podcast we’re going to be talking about two approaches to green roof design, the pros and cons of each, and factors to think about when you’re trying to make a decision about how to approach designing your green roof from the very earliest stages. And if you stick around until the end of the podcast, on the quick tips segment we’re going to be giving you three very valuable websites that we’ve come across for helping you build the data profile of the climate and the setting that you’re going to be doing your project in, which will help you make some of the fundamental choices about how you approach your green room project. So please stick around for that. So Kevin, what’s going on?

Kevin: Well Will, it’s a beautiful day here in Florida. I just came back from a green roof project that we have in progress currently, and the plants, green roof plants, always look so perky and good in the morning. And it’s lovely, it’s going to have a food component, a native plants component to support biodiversity, good storm water plants and good landscape plants, and I think as we move through the next couple podcasts, we’ll see the advantages and disadvantages of choosing the right plants for the right place.

Will: Awesome, and things are pretty quiet up here in DC. We’re keeping our fingers crossed that we’ve finally broken over from that kind of stage where it’s spring for two days and then snaps back to a winter. So we’re hoping that we’ve broken through and it’s going to be spring for good now, but we’ll see how that happens. But I’m excited about our topic for today, which is going to be really getting at the first stages of planning a green roof and talking about two fundamental approaches to thinking about planning a green roof and some of the choices that go along with those two different approaches. And of course, we start with the usual caveat that these are not written in stone, there are a lot of different approaches, and there are a lot of different hybrids and combinations to different approaches. So, take these as generally guidelines and starting points for your own research.

Kevin: Absolutely, Will. Each roof is a living organism. I like to think of each green roof as an ecosystem, and I love Wikipedia’s definition of ecosystem. If I quote Wikipedia correctly, it goes something like this: an ecosystem is a web, a community, a network of individuals arranged in a self-sustaining and complex hierarchy of a pattern and process. And what that means for green roofs is that green roofs are very complex, and before we decide and choose what plants to put on the roof, be they food plants or storm water plants or native species, we need to understand some fundamental variables, characteristics of our rooftop ecosystem. So, understanding that roofs are complex ecosystems is the first step in successfully designing a green roof that’s going to last you for a long time.

Will: Yeah, and the way we approached this podcast, and this is based off of an article that Kevin published, and we’ll have a link to that in the show notes, about two approaches to thinking about the green roof ecosystem and the way that a green roof does or does not integrate with that ecosystem. And so the two approaches to green roof design that we’re going to be talking about today: approach number one we’re going to call the landscape approach, so how would you break that down Kevin?

Kevin: The landscape approach, Will, is typified by the use of very hardy, vigorous, drought-tolerant, pest-resistant landscape plants, those plants that have proven themselves year in and year out to survive. Not necessarily native plants, they can come from just about anywhere in the world.

Will: Okay. And approach number two we’re going to be calling the native plants approach, which is pretty self-explanatory, but what’s the general thesis or philosophy behind the native plants approach?

Kevin: Well, the big push to use native plants in landscapes and on green roofs is a fact that there is an abundant amount of scientific evidence that supports the theory that the native wildlife, the insects, the pollinators, the honeybees, etc, those wildlife species that are endemic to an area or are naturalized in the area can best utilize the chemical and phytochemical constituency of native plants. Now, there’s still a lot of data that has to be assimilated before we can say that with 100% certainty. However, there is some good showing, data-wise, that local wildlife actually benefits from the use of native plants in a landscape or green roof.

Will: Okay, and so going back to the landscape approach, what are the general benefits? So, you know that a certain species of plants generally does well on a roof and so that’s how, that’s what we’re going to go with.

Kevin: Right, it’s a plug-and-play approach Will, you’re absolutely approach. The landscape plants are very readily available at most big-box retailers, most local nurseries, because they’re grown and used on a regular by nurseries, plant nurseries, nation-wide and world-wide. So number one, landscape approach plants are very readily available, and they would include your species such as, here in the southeast Mexican petunia, some of the grasses, ornamental grasses, some of the lilies, African iris, etc. And these plants, you can pretty much drop them on the roof and walk away, and they’ll continue to spread and grow without any kind of care hardly. So they’re very durable, very reasonable from a cost perspective, because demand is out there and supply is there to fulfill the demand, so there’s a sense of comfort in knowing that if I buy these plants for my green roof, I can install them and walk away and not come back in a week to find dead plants. The landscape plants have that tried-and-true component and they’re very readily available. Whereas the native plants, on the other hand Will, it’s going to be hard sometimes to find native nurseries because the demand is not there. It’s growing across the nation, but we’re still seeing a lack of supply of native plants, and, so, you may have more difficulty in finding those native species that you want to put on your roof, and because the supply is limited they may be slightly more expensive.

Will: What about just gathering them from your local area, or getting them from the neighbor or that type of approach? Is that something that’s readily doable?

Kevin: That’s a very good question, Will. You always need to make sure that you’re abiding by local regulations with respect to collecting wild plants. The states and municipalities always typically have a regulation that prohibits the digging of threatened and endangered species. A lot of the more vibrant, colorful native species are on the threatened and endangered plant list because they’re so attractive and people want them for plants in their yard, so make sure you abide by all local regulations, but yes, if you have a big yard, you might want to dedicate a spot in the backyard to grow some native plants and then harvest those occasionally. Or if your neighbor has a weedy spot, go check out those weeds, they may be some great native plants suited for your green roof.

Will: I’m really curious about this movement to move toward native plants, and the sort of economics behind that. You said that more and more nurseries are beginning to offer native plants, and that’s springing up around that country. What is really behind that movement, and how has that been developing in the last couple of years?

Kevin: Will, there’s quite a few local, native plant society chapters around the United States and the world, and these chapters are typically advocacy groups to, with a mission to help preserve endemic plants species and encourage water conservation by use of drought-tolerant native species. And over the past five-ten years, I’ve seen these groups grow in size and number, as the interest has increased in preserving local habitats. And with the advent of the internet, the explosion of web capabilities, I’m really seeing a lot of educational information come out now on the benefits of using native species to support biodiversity pollinators, bees, etc. So there’s a growing , a definitely growing focus to use native plants on green roofs and in landscapes.

Will: Okay, so say we’ve decided to go one way or the other, either we’ve found a native plants supplier that’s appropriate for us, or decided to go with the landscape approach that uses more proven plants that you can find at a lot of different nurseries. What about the maintenance requirements and things like fertilization – how do the two schools break down on fertilization?

Kevin: Well, as you mentioned earlier, it does not have to be an either-or situation. You can have a green roof, and have a small patch of natives and a small patch of landscape plants, and see what does best in your situation, and then adjust your plantings in the future accordingly. Or, you can mix the two together. But, from a fertilization and maintenance standpoint, there’s some definite differences. Typically I see on landscape plants planted green roofs, the use of slow-release fertilizer, and the advantages and disadvantages of slow-release fertilizer include that slow release is great at keeping plants alive. However, it does contribute nitrogen and potentially phosphorus to storm water, which could cause algae problems. So there’s upsides and downsides to putting fertilizer on a roof. From a native perspective, native plant perspective, I find it very interesting that a lot of science I’ve seen incorporate what I call nitrogen-fixing plants into the native plant design, instead of the use of fertilizer. And the nitrogen-producing plants are like legumes. There are some nice native legumes, they’ll grab the nitrogen out of the air, and convert it into a form that can be used by plants for fertilization, and put it into the soil so you have fertilizer in a plant, which is very interesting. There’s some good information on the web about both, but definitely if you’re going to fertilize landscape plants use a slow release, and if you’re going to put natives always consider a nitrogen-fixing native like a legume. Also, with respect to maintenance, you have watering issues. Native plants can be very drought-tolerant, and so can some landscape plants.

Will: Okay, so we’ve heard a little about fertilizer requirements. What about the general theory around irrigating with these two different types, the landscape versus native plants approach?

Kevin: Well, I’m very pleased to see that both schools of thought are now trending towards micro or drip irrigation. And there are some wonderful systems for green roofs, irrigation systems that you can find on the web, that are micro-based and drip-based, that don’t spray and lose a lot of water to evaporation, but apply the water directly where it’s needed and ultimately conserve, Will. So, there’s some great systems out there, again you can find those on the web. There have been in the past, just standard, “when the plants look bad” theory to flood the planting area with water to hope we perk the plants up, but that approach is rapidly disappearing with these new irrigation technologies. Rainwater collection is very important for both landscape and for native plant planted green roof, and collecting water is simple. You have rain barrels or underground cisterns that store the storm water collected off the roof, and that water can be recycled at a later date to irrigate the plants when it’s dry. The one downside I would caution about a rainwater collection system is in certain areas of the world, you may have a whole lot of rain during the year, but it comes in the summer months, you may have some very dry winter months, so don’t think that you’re going to irrigate your green roof all year round with a rainwater cistern. You may be able to six or nine months out of the year, but there’ll be times of drought in certain areas of the US and the world where you’ve got to supplement that irrigation with well water or potable water. And I bring that point out to mention the importance of looking at your plants during design. You don’t want to put plants that can use rainwater irrigation nine months of the year, but then require potable irrigation water the other three months, because potable water we should conserve, we do have water crises in the US and around the world, and we should not be wasting water on a roof. So it’s important to understand – we’ll get into some of these factors later on, in understanding the climatic issues of your roof. But irrigation-wise, try to take advantage of all the nature-provided irrigation – dew, fog, rainwater precipitation, recycle your rainwater, use appropriate drip and micro-irrigation techniques, and, most important of all, design your green roof to use those plants that can survive without an excess of irrigation, Will.

Will: And one other point I thought we should hit with respect to water, is that we’re thinking of native plants as part of your local ecosystem, and of course the groundwater that’s already present in the soil is part of that for native plants, but up on the roof, that’s going to be a totally different game. How do you deal with some of those issues?

Kevin: Exactly. You need to understand your plants and that goes back to the saying right plant, right place. You would not want to put a native species that is happy in wet, soggy soils on a roof because, unless you’re pumping a lot of irrigation up there, it’s going to be dry and hot at times. So, understanding soil science, and understanding the soil that your native plants grow in, and your landscape plants, is important because you don’t have native hydrology on a green roof. You have a very alien, foreign type of soil hydrology on green roofs.

Will: Okay. Now, I’m really interested in this question – I think we’ve been talking from the point of view of an individual homeowner, someone who’s thinking about installing a green roof. But let’s zoom back out to the level of society, and we’re trying to promote green roofs, trying to increase the number of green roofs, it seems like the landscape approach where you have a certain number of plants, and you know they’re going to work very well across a large number of projects, might be a little more scalable, so it might be better suited to creating a large number of new green roof projects in a short amount of time. Whereas the native plants approach is going to take a little bit more time, because you need to be intimately familiar with the local setting, the plants that are going to survive there, you need to gather all this data about your setting. So how do you think about that trade-off between scalability and the native plants approach seems a little bit more, not one-size-fit- all, more project by project?

Kevin: Right, and you bring up a very valid point, Will. Because there’s so much knowledge about these landscape plants, because there’s so many of them, and because they’re used so often, the economics are very profit-friendly to use landscape plants. Again, they don’t cost much, are very readily available, and you can fill your truck-bed up with landscape plants and go to a green roof and bang! You’ve got a lot of green, a lot of texture, and a lot of color. So for most people, there’s an economic friendliness to using landscape plants. On the other hand, native plants can be thought of the some way, it’s just the supply is not as readily available. Once you understand native plants, sometimes they’re just as economically friendly, but they do require a little bit more thought because they haven’t been used as often. And we as a population and we as green roof designers, we don’t have that familiarity with native plants that we do with landscape plants. So, there’s a definite benefit, economic benefit for using landscape plants. You are right, they’re more scalable, they’re plug-and-play, very quick.

Will: Okay, well I think we’ve given our listeners plenty of food for thought for thinking about the two approaches and which might be right for them, but once you’ve made this decision, or maybe to make you before you or as you are making this decision, we recommend doing something that we call “building a site profile,” which, simply put, is just gathering as much data as you can about your local climate, your local conditions, what native plants might do well or might not do well on a green roof, and we just wanted to run quickly through these points and maybe point you to some resources or some tips to help you think through these issues. So, Kevin do you want me to just run through each one and we can discuss each one quickly?

Kevin: Absolutely, Will.

Will: Okay, so let’s start with wind speed and direction.

Kevin: Okay, well let me back up just a second. You know, in the morning when I get up, I always look at the weather because I want to know how to dress accoringly: is it going to rain, is there going to be sunshine, cold, hot, etc. And we should think about green roofs before we design and install in the same manner. What are we dealing with climatically? What kind of climate conditions are we dealing with? We need to know the fundamental basics of that ecosystem so we can chose the proper plants for that roof. There are so many different climate variables, and we are going to talk, Will and I, we are going to talk about those variables. But the two primary design variables that impact a green roof choice the most are (a) light and (b) wind. And so, those are the two primary design variables. Now we’ll also discuss secondary design variables, which will be temperature and many others.

To answer Will’s question, understanding wind exposure is critical to green roof design. Understanding light exposure is critical to green roof design. We’ll get into these more in detail in future podcasts, but in a nutshell, wind can kill a green roof. What happens is if you have a consistently strong desiccating wind, dry wind, you remove the water from the leaf, and without water your plant cannot conduct photosynthesis and it will die. A lot of approaches that I’ve seen in the past to alleviating wind issues is to pump more irrigation on the plants roots, but what happens is that you have if you have a strong, continual wind, Will, the water is going to be be desiccated so quickly from the leaf that the vascular system of the plant cannot keep up pumping enough water to the leaf to keep the plant alive. So, understanding how much wind you have on your roof, what kind of wind exposure, is crucial. We’ll talk about some of the ways to limit that wind exposure, like parapets or wind breaks, how to use different types of plants to serve as wind breaks. So wind is a very important factor in green roof design to understand, Will.

Will: Okay, so you’ve got data about your wind and you need to know not just at one given time, but you need a profile of how that changes through the year and the seasons, is that right?

Kevin: That’s important, absolutely, because you will have in some areas strong winds in the winter, strong winds in the summer, or vice versa, and you can design your plants to accommodate both.

Will: Okay, and so primary factor number one when you’re creating your site profile is wind. What about the second one you mentioned, which is light?

Kevin: All plants need light, Will, to live. So you need to know: do I have a southern exposure? Eastern, western, northern exposure? How many daylight hours do I have? What is the solar intensity? And light availability, like wind, without light, your plant’s not going to conduct photosynthesis, it will die. Light exposure and wind exposure are the two primary design variables in a green roof. We’ll talk more in detail as to why these are the most important. Some people would think that maybe temperature is more important than light or wind, and temperature is very important, but we have found that it’s not one of the two primary design variables such as wind and light. We’ll about talk briefly a few resources that are available, and Will’s going to point these links out that will allow someone to look at the historical data trends on available light and wind exposure, for any given point in the US and the world.

Will: Alright. So, we’ve got wind and we’ve got light, and now, what about some of the secondaries? What about temperature, rainfall, that sort of thing?

Kevin: Yeah, Will, those are important, and we’ll discuss those later. They help fine tune the plants for your system. The primary variables like wind really point us in the direction of the different families of plants to use on a green roof. The temperatures and precipitation, or available water vapor amounts, will allow us to fine tune and look into the genus and the species of which plants to use, and allow us to fine tune the colors and the textures that ultimately will decor our green roofs. So water vapor and temperature, adjacent plants that could potentially impact the growth habit of green roof plants, leaf litter, smog, there’s a variety, a number of secondary factors that we’ll explore.

Will: Okay, Kevin and I just took a little break, and we were just marveling at how much more there is here, and how much detail there is that we don’t have time for unfortunately in this episode. But I just had one more question about building a site profile that might help some new listeners. Say you were dropped in a different state: you’re in Florida, say you were dropped in California and you were walking around a neighborhood where you were going to install a new green roof there. What are some of the things you would look at when you’re looking at a site? What are the things you would look for, what would you write down in your notebook, what would you notice and not notice?

Kevin: First of all, I’d try to visit the site as often as possible, Will. It’s important to understand the site not only at one day out of 365, but understand the site in the spring, the summer, the fall and the winter. Of course that’s not always feasible, and that’s why the historical data on the web is important. But get out to the site as quick and as often as you can. Look for the sun’s paths, look for adjacent trees that could cast shade on your roof, look for anything that could ultimately impact your roof, and then, most importantly, what we’ve talked about before, look at plants that are growing in the gutters. They’ll give you a good indication of a lot of information valuable for green roof design.

Will: Alright. And now, we’re going to go directly to the quick tip today, which is a few resources that will help you gather some of this data, some of this longer term climate data about your site, which will help you when you’re making these choices, these fundamental choices about what type of approach you’re going to use when you start your green roof and select your plants. So the first one is www.worldclimate.com. What can we find there?

Kevin: It’s a wonderful portal for climate data and climate resources. If you’re wanting to know how much rain your green roof project in Portland, Oregon, will receive in any given month of the year, or in the Caribbean, or in Africa, or in Europe, then this is a wonderful site to just get good general information. Am I dealing with a site that’s going to be exposed to a lot of sun, or be very dry, or have a lot of water, and if so how much rainfall can I expect?

Will: Alright, that’s number one. Number two is www.climate-charts.com.

Kevin: This is some good technical data here, Will. Lots of charts, lots of maps, lots of graphs, lots of data, and also other links to technical resources. So if you are a designer and you’re wanting to collect some good data to support your ultimate green roof design, then this site can be very helpful.

Will: Alright. And the third one has a very long URL, so I’m going to try to read that out here, but I’ll have a link to that in the show notes. And it’s the US Drought Maps and Data.

Kevin: Sure, Will. We want to know, any time we design a green roof, if we’re going to be exposed to harsh conditions, and this site really focuses on the history of droughts in regional areas of the US. It’s a great site, some great graphics, and very good data.

Will: Alright! And that is going to wrap it up for today’s podcast, episode number four. We want to thank you all very much for listening. And one little breakthrough for us is this is our fourth episode and we’ve gotten our podcast approved in the iTunes store, so we’re both going to have links to that in our show notes, and I’ll give Kevin a link for his site, so we encourage you all to grab our podcasts in iTunes so that you can get each episode as it comes out. We’re going be aiming at doing one podcast a week roughly, and we look forward to hearing what you all have to say and your thoughts on the podcast. Until next time, have a great week!

Will: This is the Green Roof Podcast episode 3. Hi everyone, welcome to the green roof podcast, the podcast dedicated to helping you get your home or business on the road to a beautiful energy saving living roof. Even if you are just starting today, my name is Will Ward

Kevin: My name is Kevin Songer and hello from sunny and hot Florida today

Will: Can you believe that we are on episode 3 already?

Kevin: Time flies

Will: Anyway today on Episode Three we are going to be talking about the essential components of a green roof  system and when I say essential there is an asterisk by that because there is really no world standard for a green roof system and  you can have something as simple as a home built into the side of the hill with sod covering it or various types of economic or likely green roof systems that have very few components are extremely simple and I hope we will be able to get into those in more detail in the future episodes. But what we are going to be talking about today are the generally accepted standard components of a green roof that you would find in a house, in a single family house in North America. Is that how you describe this Kevin?

Kevin: That is right Will, absolutely. There are as many different ways to build a green roof as you can imagine but there are some good tried and proved methods and those are the ones we will be talking about today.

Will: So, the way we decided to structure this is starting from the bottom up so you have your underlying structure, the roof surface and above that the first layer of your green roof system is going to be a water proof membrane, which in most cases will also function as a root barrier to keep the roots of your plants from penetrating and going below the bottom of your up green roof system. So what are, what is the general purpose of this layer, Kevin, and what are the things you look for when you are thinking about designing this layer?

Kevin: Right Will, we have to remember that green roofs are friends to our existing roofs, they are not enemies. However there are some factors associated with green roofs that do call for some protection of the underlying roof system. We want to keep water off of the underlying root system and we want to keep roots from growing into the existing roof system or after so a water proofing membrane root barrier is the first, the first layer you will see on most green roof systems and they come in, the membrane comes in propylene polyethylene or a sprayed on elastomer. The root barrier is typically the waterproofing membrane with extra engineering and design to prevent roots from growing through the membrane.

Will: And if you could walk me through, say I have some people coming over this afternoon to install one of these water proof membranes, what is the process, how did it happen, what is it look like and about how long is it take? That stage of the process

Kevin: Sure Will, if your system that you are purchasing uses a water proofing or root barrier membrane then you are more than likely it will look like a big sheet of black plastic and the roofers will carry it up and attach it to your roof by a number of different methods typically the most common is a low Volta organic compound, a low VOC adhesive and membrane is laid directly down on your roof. If it is a sprayed on elastomer then they will have a bag packed of swords with a hose and spray nozzle and they will be spraying the, the membrane directly over top of your existing roof so there is a variety of products. Typically the application or installation of your water proofing membrane and root barrier is a very quick process and should not take too long

Will: And just looking around on the net there are dozens of companies that offer this type of product but you have any tips for someone looking and trying to choose between all of these.

Kevin: Well it depends on their budget of course. I will talk to different representatives from the products and find out what they advantages and disadvantages are of each product. There a very unique Hydrotech system that say a sprayed on type system, there are couple of great fire stone liners, so again it just depends upon what the preference of the client is and their budget. I would always recommend several bids, several quotes to make sure that you are getting the best bank for the buck with respect to the water proofing membrane.

Will: Okay so we have got out water proof membrane down and that is also functioning as a root barrier to keep the roots from penetrating through that membrane and interfering with the structure of the root. And the second layer of the green roof system is the moisture retention and drainage layer. So its two functions are number one to retain some water to allow the plants to grow but then also to drain water away from the house and filter it down to your drainage system so that it keeps a lot of weight from humiliating on from the house structure. Is that generally how you look at it?

Kevin: That is correct Will. Green roof plants typically don’t like to have what I call wet feet. So, after it rains, they don’t want to sit in a puddle of water. These plants are designed to withstand drought typically or long periods of drought. Even those that have your irrigation systems and most of the more drought color plants such a succulents like sedum, they don’t like to have what I call wet feet so it is important that we move any kind of rain fall or storm water away from the plants and off the roof as quickly as possible. Having said that, there are a couple of products and moisture retention products that either a fabric that absorb water and hold water much like a diaper or fabrics that have little cups simple, excuse me molder plastic panels that have dimples that serve to hold water and so the plants can take advantage of the water in the future. From a stormwater perspective it is also important to be able to move water quickly out through roof because you, water is very heavy Will, you don’t want to have too much of a water build up because your structure could be comprised if you had a lot of water standing and pooling on the roof so the drainage layer is very important.

Will: Some of the dimple products are very interesting design because they allow water to go only up to fill up the small little cup of the dimple and I guess the easiest way to demonstrate this would be with a picture which we will have in the show notes, but once the water fills up that indentation in the dimple any access water will flow over the top and then it is filtered off into the regular drainage system and that there are a number of companies that do that. Are there ones that you would recommend or ones that you work with a lot when you are doing green roofs?

Kevin: Again I would say do you research on the Internet. I think that water retention products are very important but honestly Will I think specifying the right plants for the roof is probably more important because there is a fundamental problem with irrigation. When you have high desiccating winds like many cities do during the winter time when it is cold and the air is very dry, doesn’t matter how much water is around the roots of the plants, green roof plants, doesn’t matter how much irrigation you apply to it, doesn’t matter how much water is absorbed in fabric on in the dimples of water retention panels. If the wind is too, too fast and too desiccating, the vascular system in the plants are not going to be able to provide enough water to the leaves and they are going to have plant desiccation occur. So the panels are important and the fabric is important but I typically focus on other aspects of the green roof rather than the water retention aspects as more of an area to understand and make sure your design is correct.

Will: And the other function of this layer is the drainage function so what are the different ways or structure that accomplish the drainage function, how does that work?

Kevin: There is two basic types of drainage systems for green roofs Will. The first is arrogate or gravel based drainage system, much like a drainage field in your septic tank drain field and then there is a polymer type woven drainage mat which is like a big sponge or a big piece of half inch thick walcrow that allows the water to flow down, keeps the gravel above and facilitates drainage but as we mention drainage is very important aspect of a green roof system.

Will: Okay and if you are looking at the aggregate system what are some of the tips that you have when you are looking for that type of system. What are you looking for?

Kevin: Well there is a lot of material that will work well as arrogate in a drainage system for a green roof. You can use a gravel, you can use a crushed brick, any other type of recycled crushed glass, what you want to make sure of a couple of things. You want to make sure that the material is free from very fine dust and I typically say keep your fines, fines being the amount of material that we pass through a number two hundred sieve, keep those less than seven percent, five to seven percent and you don’t want the material that you use for drainage to either lower or elevate the PH of your stone water and you don’t want it to contribute to any kind of a acute toxicity either so ASTM has a great standard D448 size number 8. I would check out that standard when looking that gravel for a drainage layer

Will: Okay and if you are going with the filtered fabric type system what do you look for in that type system.

Kevin: Typically Will a filter fabric goes above the gravel and excusive swarm media which may contain some organic material from clogging up the drainage layer so a filtered fabric goes on top of your poly drainage mat or your gravel and what I see most of in filtered fabric is it is made from a non woven geosynthetic material much like a rock wall or a wool blanket will sit on top of your drainage layer and basically all it does is keep the drainage layer from clogging up with the soil from the green roof soil media but it is a very important component within the green roof system so after you see your roof will lay down the water proofing membrane and the drainage layer, then on top of drainage layer goes the filtered fabric.

Will: Okay so we have got our water proof membrane, we have got our moisture retention layer, we have got the drainage layer, we have got the filtered fabric to prevent the soil media from going down into the drainage layer. Let’s talk a little bit about the soil media. What are the main things that we are looking for in a soil mixture for a green roof?

Kevin: Well you want your soil media to be light weight number one, keep heavy things off the roof. The lighter the better, number two you want it to be able to hold water, retain water from a storm water perspective and from a watering the plants perspective. You want it to be able to grow plants so it has to have a wide range of characteristics that enable plants to dry such as, we want our soil media to have a PH of somewhere between six or six and a half and eight, six and half being the lower side, eight being the highest side. We would like to see soluble salts less than three or four grams per liter potassium chloride. Importantly we want that soil media Will, to drain water well. So the hydraulic conductivity, we  look for a value of at least one two inches per hour which is 30 to 55 millimeters per hour and you don’t want your soil media to have a lot of large stones in it and this is particularly true of the cyclone and hurricane areas like we live here in Florida but also as we see more and more tornados come across the Midwest, you want that green roof soil media to be small and nothing large that could be picked up in wind storm and damage adjacent fenestration or windows so this is some of the qualities that we look for in green roof soil media. Certainly we want it to be able to support plant growth that is very important and through trial and error, talk to some good gardeners, you know, there is an extreme science involved in development of a green roof soil media and it is very interesting.

Will: Ya and one of those areas which we touched on a little bit in our discussion before recording is the controversy I guess we should say, over whether or not to use shale or expanded shale as part of this mixture of your green roof substrate. So can you talk a little bit about that controversy and how you see shale factoring in or not factoring into the sustainable green roof system.

Kevin: Great, great thought Will. There some wonderful arguments for both the use sim for the non use of expanded shale in green roof soil media. Referring to the argument first, it is a very prominent material. Once you put expanded shale on to a green roof you don’t have to worry about it. It is there forever, very light weight and has a great water absorption capacity so there is many benefits to using expanded shale. However on the downside, some of the, I have seen some articles recently that talk about the extremely high carbon footprint of expanded shale because shale is mind out of the ground so you have a strip mining component. Now it is a side product of coal and other petroleum type manufacturing processes but still you are involved in strip mining and then you take and you use petroleum based fuel and furnace to fire the shale up a thousands of degrees to where it just kind of expands like pop corn so you have a huge carbon foot print associated with expanded shale now I have heard the arguments well that carbon foot prints are a onetime cost and because it is permanent you don’t have an ongoing carbon foot print however I have also seen articles that talk about the virtues of using something a little bit more sustainable like sand or even organic compost. So the jury to allow or see which way the market takes the green roof industry with respect to expanded shale.

Will: Ya we will have to get into that a little bit deeper in a later episode but I guess if I were to pull out the top three ideas from what we are looking for in the growing media is, we want it to be lightweight enough so that we are not adding a ton of extra load to the roof surface. We want it to facilitate drainage so we want it to not retain water and we also want it to have an extra top soil so that we have enough nutrients to grow the plant. Does that sound right?

Kevin: That is right. You can use the term organic material instead of top soil so could either be top soil or could be compost. We are doing a project right now where the green roof soil media is being manufactured on site from similar local materials because it is any place that is, does not have access to transportation to get the shale or some of the other products in and in addition to the crushed limestone that we are using, we are using some local homemade organic compost so top soil or compost, yes you have to have that organic component in your green roof soil media for the plants to be able to grow and thrive.

Will: Okay so we have covered the water proof membrane and the root barrier, we have covered the moisture retention and drainage layer, we have covered the growing media mixture, now we are going to get into some of the things that you won’t find on every green roof or some things that are a little bit less common depending on or dependant on the structure that you are building on your particular project. So what are some of the other components that you may or may not find on say a residential green roof in North America?

Kevin: Well if the green roof is going to be accessible then certainly you want to make sure the design is in accordance with all safety standards, all local and state federal safety standards, hand royals potentially, definitely anti slip devices, there is also a very interesting new science, it is not new science, I have just seen a research of interest in it lately, it is fog catchers and dew catchers where people are taking advantage atmosphere of water vapor, capturing the water vapor and irrigating the roof with the water vapor and then you know, the typical amenities that you would see on a garden roof in some areas, benches and containers, again you need to be careful and check with your building code and make sure that what you put on a roof is allowed and it is not going to become air borne during that wind storm.

Will: And speaking of wind, what about, if I am in an area, you know, high windy area and I am worried about soil erosion or you know the soil blowing off the roof, are there any devices that help control that?

Kevin: There are Will, there is some very interesting biodegradable wind erosion mats, many of them are easily found on the internet just type in erosion mat or wind mat for green roof and it is a very interesting products and what they do is hold the soil in place, hold the green roof soil media down until the plants, the root systems can become established and once the root systems on the plants are established the erosion control mats are bio degraded if at time.

Will: Alright, well I think one thing that this absolutely has shown me that we are just scratching the surface with all the different variations and types of materials and options that this home owners or business owners who are putting in a green roof and we certainly have a lot of material for future episodes but I think that is all the time we have for today so I wanted in today’s quick tip point you to a page that I put on greenroofplan.com which is a survey so if you go to a www.greenroofplan.com/survey you will find a five or six question survey that I hope you all will just take a couple of minutes to fill out and that will let us know a little bit about what topics you are interested in and what you know, are you home owner, are you business owner, are you someone working in the green roof industry. It will help us guide a little bit more in what topics we cover and what kind of information we provide. So again, we encourage you all to go to www.greenroofplan.com/survey and that will help us provide more relevant and hopefully interesting green roof podcast as we go forward. So thank you all very much for listening and we will see you next time.

Create your free online surveys with SurveyMonkey, the world’s leading questionnaire tool.

Will: This is the Green Roof Podcast, Episode Two.  Hi everyone, this is the Green Roof Podcast episode 2, the podcast dedicated to helping your home or business get on the road to a beautiful, energy saving living roof, even if you’re just starting today.  Welcome to our second episode, my name is Will Ward

Kevin: And I’m Kevin Songer

Will: And today we have a special announcement that we will be bidding farewell to good ‘ol Dave Hilary. Dave Hilary was a pen name that I used for the first year of Green Roof Plan.  And when I started the site it was kind of a side project, and I wasn’t quite sure what would happen to it; it was an article based site.  And for those two reasons I decided to publish the articles under a pen name. But as the site has grown over the past year and I’ve been interacting with more and more people, it just became less comfortable to be using a pen name, and I felt that it was getting kind of ridiculous,  and I should just switch to my real name, which is Will.  So that’s me and I apologize if anyone is uncomfortable with that, but I’m hoping to make a fresh start today.

In today’s episode we are going to be going over the different types of green roofs and what you can expect from each. And I know when I was first starting the research for Green Roof Plan, I was a little bit confused by all the different distinctions between extensive and intensive green roofs, and semi-intensive, and it seemed like each source had their own definition of what they were, and there was a little bit of overlap, and the borderlines between the various types weren’t very clear.  Kevin, is that what you found as well?

Kevin: Absolutely.  There are a lot of descriptive terms with respect to green roofs, and some are quite technical.  However the best way to remember it is that green roofs are really just plants on a roof, and we’ll talk about some of the more descriptive terms today.

Will: So why don’t we start with the two main classification of green roof which are extensive and intensive, so what’s the difference between those two?

Kevin: Very simple.  Extensive green roofs are shallow green roofs, and intensive, they’re just the opposite.  You can think of “intensive care,” a room in the hospital, very detailed, very thick in soil media, and quite complicated.

Will: And what type of projects would the two different types of roof be suited for?

Kevin: Will, that’s a great question. Really both roofs have very specific applications, and an extensive green roof is typically used on a residence or a roof that cannot support the extreme weight that you typically see on an intensive green roof, so extensive green roofs might be found on a shed, a garage, a commercial building, a café, a restaurant, whereas intensive green roofs are more suited for large commercial buildings that are structurally and architecturally designed to handle the extra loading.

Will: Another borderline between extensive and intensive roofs is the need for irrigation, so how does that break down in your thinking?

Kevin: Good question, Will. There really are no specific requirements for irrigation on either extensive or intensive green roofs, however irrigation is a very important component on both. We typically see that extensive green roofs are designed to accommodate what I call “nature irrigation” or rainfall, precipitation, water vapor, dew and fog, whereas intensive green roofs, because of the thickness of the soil media, they typically have a micro-drip type irrigation or recycled rainwater irrigation system installed.

Will: Another way that these break down – and this is the way I have it explained in the ebook on my site- is by soil depth as the main variable that separates these out, and the way I had it organized was an intensive roof is going to have around 8 inches of growing medium, whereas a semi-intensive, which is the middle zone would be 4-8, and then the extensive, the shallowest, would be something like 1-4 in terms of growing medium depth – does that sound about right?

Kevin: That’s correct. The weight of the roof increases exponentially with each additional inch of soil media, especially when saturated, so typically the industry has delineated extensive roofs as those living roofs that have soil depths of less than four inches and intensive as having eight inches or more, and of course the semi-intensive or semi-extensive, however you wish to refer, as hybrids somewhere in between the four and eight inches.

Will: So, with these different soil depths of extensive versus intensive green roofs, naturally different types of plants are going to be able to grow in them, so what are the guidelines you think about for intensive versus extensive roofs?

Kevin: There’s been a lot of research done around the world by the Germans, the Europeans, who really have a considerable number of years of research and experience in planting green roofs. As to which plants to use, this is one of my favorite topics. I love to look around the world and talk to people from around the world and see their experience as to which plants have done best on extensive roofs, and which are more suited for intensive roofs.  And, of course, the extensive roofs, having a shallower soil media, requires plants that can grow in soil that has depths of – as we said – less than four inches. A good place to look for these types of plants are those plants that do well on rocky crevices or outcrops, or in very sandy soil. Intensive green roofs, the plants that can grow there, the choices are virtually unlimited, so you have a lot more, you can adapt the soil composition to exactly what you need, and install those plants to suit your preferences.

Will: And the last variable, which a lot of people are going to be thinking about with extensive versus intensive is the cost, so with an intensive roof, very likely you’re going to have drip irrigation built-in, you’re going to have deeper soil, you’re probably going to have a wider variety of plants, so I imagine all that would add up to generally a higher cost for the intensive. But do you have any guidelines when you’re thinking about costing out an intensive versus extensive project?

Kevin: Yes, Will, absolutely. We see intensive green roofs more and more being installed on municipal buildings or government-funded projects, those projects that have a larger budget and can afford the additional architectural support that’s required to successfully hold an intensive green roof. You’ll recall we just had a green roof collapse in Chicago from a snow build-up. So it’s vital, as you mentioned in the last podcast, critically important, that your structural system in the building can handle the heavy weight of an intensive green roof, and, as such, intensive green roofs are going to be a lot more expensive because you have not only the structural components, but you also have a variety of system components that are installed such as irrigation. And we see the cost of intensive green roofs ranging anywhere from $20 per square foot to $100 per square foot or more, depending on the plants and the type of system, and of course the structural requirements. And extensive green roofs just the opposite: I look at extensive green roofs, Will, as being more a cost-effective green roof or living roof available to most people and a DYI kit can run from $5 a square foot to as much as you want to spend. So extensive green roofs are a lot more cost effective, they’re a lot lighter, and require much less support architecturally. Of course, it’s very important when installing a green roof that you always check with a structural engineer or architect to make sure that your structure can hold and support the green roof.

Will: Yeah, and that’s really a whole other dimension of cost that can potentially be added to a green roof. When you have a structural engineer out and you need to do reinforcement to the underlying structure, have you had any projects you’ve worked on where that’s been an issue and you’ve had to rework an underlying structure to make it able to support a green roof project?

Kevin: That’s all based on the desires of the client, Will. If the client does not have the funds to beef up the structure then generally what we do is scale-down the roof to match what his existing structure possesses. However, in a situation where there’s a commercial building and someone wants a very nice rooftop garden or living roof, then if the funds are available it’s certainly very easy to go in and retrofit the roof to accommodate the additional support requirements.

Will: Okay I think we’ve covered extensive versus intensive pretty well. The other major category that green roofs break down along is modular green roof systems versus built in place green roof systems. How would you explain that to someone who is first getting into green roofing for the first time?

Kevin: Sure, Will. The modular ones are ready to install. You have beauty, you have greenery, you have habitat, storm water control, ready to go, just set in place, much like a set of building blocks children would use. However, a build in place-type system is more, you bring the dirt, the soil media in, you typically have an array of smaller plants, generally plugs, and it may take a while, some time, for those plants to grow-in and give you solid coverage, so I would best describe modular as a ready to go, fully grown system that you can just set on your roof, plug and play type, and go, whereas a built in place system would be much like building a race bed to your garden adding the soil media, adding the plants, watering, and watching them grow.

Will: So if you were an individual homeowner, what are the guidelines you would be thinking about if you were trying to decide between a modular system or a built in place unique system?

Kevin: Sure, there are advantages and disadvantages to both. Modular systems are great. They don’t work in Florida as well as they do in other parts of the United States because we have cyclones and hurricanes here, and a modular system may blow off in a Category 3 hurricane, whereas a built in place is more designed to withstand more environmental factors. However, modular systems now are being designed to also withstand environmental issues, so you need to check with your building code. But if I was a homeowner, I would look at both. It depends also on how much I want to get involved in the design, installation of the living roof. There’s advantages to really understanding in depth and in detail your system, so if I just wanted greenery and didn’t really want to become involved in design I would really go with a modular system. However, personally I love to look at how soil media is working and understand root architecture and see how the plants are doing and look at the thermal efficiency, so again, it’s purely the homeowner’s choice depending upon their level of interest and involvement.

Will: And if you’re interested in more information about modular green roofs, usually some of the bigger green roofing companies offer ready to go modular systems, so just two of those, if people want to go check those out: www.greengridgridroofs.com and www.liveroof.com are two companies that make modular green roof systems. And what about, you know, looking at some of the modular companies it seems in general, their projects are tailored towards bigger urban buildings, doing an entire rooftop of an apartment building, that type of project, but there are modular systems that can be tailored or scaled-down to an individual home, is that correct?

Kevin: That’s correct. In fact I saw an advertisement on the internet that Toyota, I believe it is, actually has a small carpet-like grass that they’ve developed that comes in 2 foot by 2 foot or 1 meter by 1 meter squares that you can just lay on top of your roof, so there are modular systems that are available for residences, and certainly the internet is a great way to find out about those.

Will: Alright, well I think that wraps up our discussion today about the different types of green roofs: extensive versus intensive, and modular versus built in place, and I think Kevin has our quick tip for today.

Kevin: Absolutely. You know, Will, last week we talked about the benefits of living roofs, and there’s a great article that’s just recently been published by the Columbia Daily Tribune out of Columbia, Missouri, and if you go to Will’s website I will pass that link on to Will and it’s well worth your time and reading.

Will: That, I think, is going to wrap it up for today. I want to thank everyone for listening and thank Kevin, and don’t forget to check out his website, which is http://kevinsonger.blogspot.com which has all of his green roof research and pictures of projects that he’s working on, and a ton of other useful information, and as always, please if you have a comment or question, or suggestion for something that you’d like us to cover in the podcast, please leave that in the comments. Thank you all for listening to the Green Roof Podcast, and we’ll see you next time.

Dave: This is the Green Roof Podcast Episode 1. Welcome to the Green Roof Podcast, the podcast dedicated to helping you get your home or business on the road to a beautiful, energy-saving green roof, even if you’re just starting today. Hi everyone, and welcome to the first Green Roof Podcast, this is Dave Hilary.

Kevin: And I’m Kevin Songer

Dave: And today we are kicking off what we hope is the first of many podcasts where we talk about the benefits of installing a green roof on your home or small business, condo building or what have you, and talking about some of the ins and outs of the process.  We are doing this podcast to help home and business owners get educated about the benefits of green roofs and hope more people will be inspired to install them on their own homes or projects.

I just wanted to start off with a quick announcement, I was doing a little search on the iTunes store, and even though this is our first episode, the good news is we are already number one on iTunes, because we will be the only green roof podcast available, so congratulations to us for that!

Today we are going to start off with going through the top ten benefits of installing a green roof, but since this is the first episode, why don’t we step back a little bit and introduce ourselves.

My name is Dave and I live in Washington DC and I first got interested in green roofs because I live in a condo building, just moved in a couple years ago, and they have a green roof there, and I started doing a little background research and learned more and more about the benefits of green roofs, and got more and more interested in it the more I learned. Then about a year ago I started a website called greenroofplan.com which is the result of many interviews and research projects that I did on green roofs, and it’s a site dedicated to helping homeowners learn about green roofs and giving them information to get started.  And with me today is Kevin Songer, and I’ll let him say a few words about himself.

Kevin: Thank you, Dave, and good morning.  My name’s Kevin, my undergrad is in biology and I also have a law degree focusing on environmental law.  My wife Judy and I are south Florida natives and we have worked with plants for many years. We have worked with trying to grow plants on roofs for many years, and we are very excited about the wonderful potential green roofs have to offer, for many reasons which we’ll discuss today, and I’m looking forward to talking with Dave about it further

Dave: And I’m looking forward to continuing to hear those beautiful bird sounds in the background coming from Kevin’s end.  He’s got the perfect setting for recording this I think.

Kevin: You know, Dave, since we’ve started adding plants to the roof, the birds have come en masse, and it’s truly amazing to watch the hummingbirds and different types of migratory birds and butterflies, pollinators, come to the plants on the green roof.

Dave: Alright, so let’s move on to the main segment, which is going through the top ten benefits of installing a green roof, and I wanted to kick that off by mentioning a Reuters report last week that said – and we’ll have the link to this in the show notes – that the green roof industry grew 28.5% last year, in 2010, which just goes to show that more and more people are really getting on board and starting to discover the benefits, the enormous benefits that having a green roof can offer. And today we’re going to go quickly through the top ten of those, so number one is controlling stormwater runoff.

Kevin: And this is important, Dave.  What we have found and what we have seen based on field observations over the past years is that most green roofs will absorb all of the rainfall from a one inch event or less.  That means less runoff that carries pollution into our waterways, rivers, and streams, and certainly has a very positive ecological benefit.

Dave: Let’s move on to the second one.  And as we’re hearing the birds in Kevin’s background, number two is “providing a habitat for plants and insects, and wildlife”

Kevin: Absolutely, Dave.  You know we’ve got stormwater listed as number one, and many municipalities and cities and organizations highly recommend green roofs to control and attenuate stormwater.  However, in my opinion as a biologist, biodiversity ranks side by side with stormwater control.  You know we’ve created what I call “horizontal green” in the urban core.  We used to have vertical green – massive amounts of forests, trees, but today it’s the asphalt jungle rather than the native jungle.  And so with the loss of habitat that loss of vertical green, as I call it, wildlife has had to look elsewhere, and by restoring that vertical green in the form of green roofs back in the urban core, what we’re doing is bringing habitat back to cities, and that’s important, and I have a slogan Dave that says – I copied it, stole it – “if you build it they will come” and that’s so true.

Many of these species that we are seeing that are threatened or endangered now, they require green above 2-3 meters to escape their predators and once you build a green roof, what we’ve noticed here in Florida is that you’ll start to see the Florida Tree Frog and Florida Anoles re-appear, and that’s just the beginning because the Anole, which is a lizard, and the tree frog, you’ll have the other forms of wildlife that are up the food chain start to come to feed on tree frogs and green roofs, all the way up to eagles.  I’ve seen eagles circling.  We have a swallow tailed kite and an osprey that visit us on a regular basis, so providing habitat is a crucial important aspect of green roofs’ supporting biodiversity

Dave: Yeah, unfortunately, the green roofs that’s up on top of my building here in Washington does not bring in that much a diversity of lizards and birds, etc, but it is nice to just have that green space up on our rooftop deck area, and it just makes a lot more relaxing place and so there’s such a range of different types of green roofs, but they all provide some kind of a benefit in terms of having living things up there.

Kevin: No doubt.

Dave: So let’s move on to number three, carbon sequestration and oxygen production.

Kevin: For every 20,000 leaves that we have, nature pumps out enough oxygen for one person to breathe, so plants are crucial to providing oxygen, controlling air pollution in the urban core, and what better way to do it than on a green roof, and of course, plants, as part of the photosynthetic process in producing oxygen, they take in carbon, carbon dioxide and sequester that as plant biomass, so green roofs are doing the ecology of our cities’ urban core a huge favor by sequestering carbon and producing oxygen.

Dave: All right, let’s move on to number four, the fourth top benefit of installing a green roof “managing pests”

Kevin: Dave, we touched briefly on that talking about habitat but what we see is when the tree frogs and Anoles, the lizards, come to the green roofs, they eat termites, house flies, ants, and other pest insects, so it’s all part of nature’s plan for controlling exotic and invasive creatures.

Dave: I wanted to ask you this, have you ever had a situation where the green roof has become a home for pests and there’s been a problem with insects that are coming there?

Kevin: No, not really, Dave.  It’s just the opposite.  Some people may consider a lizard a pest, but most don’t and there relatively innocuous, harmless, and they’re fun to watch and of course they eat lots and lots of flies and ants and termites, so I have not seen a case where a green roof really does provide a home for exotic or invasive pests.

Dave: Alright, and so the fifth top benefit of installing a green roof is just the sense of beauty and sense of place that it can add, really in some cases re-claiming that rooftop surface as a place to hang out, place to enjoy nature.

Kevin: Oh no doubt, look at your website, the photos are beautiful, and just google “green roofs” they’re truly an amazing wonder of the world.

Dave: Moving on to number six, the sixth top benefit of installing a green roof is that certain types of green roofs, intensive green roofs, which have deeper soil – and we’re going to get into some of this in later episodes – but certain types of green roofs you can actually grow food and herbs and other edible plants up there.

Kevin: We love rooftop gardening, and it’s my opinion that one of the new frontiers for green roofs is going to be growing food, providing places to grow food.  Right now I’ve got a great little green roof that has black eyed peas and what I call Matt’s wild cherry tomatoes, they are little Tommy Toed tomatoes, and within a month we’ll have thousands and thousands of cherry tomatoes, so it’s a lot of fun to grow food on our roof, and it’s a good use of otherwise wasted space.

Dave: I just wanted to take this opportunity to plug one of my favorite restaurants here in DC, which is called the Tabard Inn, and if you google their name they have a rooftop vegetable garden and they harvest vegetables and herbs that they cook in their food, and I was over there for brunch the other day, and can tell you it is some fantastic stuff.  They have some really good pictures of their roof up there, so everyone should go check that out.

Now, let’s get down to the brass tacks economic benefits of green roofs, and the top seven benefit is the cost savings you’ll get because green roofs lengthen – by protecting the roof surface – they can actually lengthen, and in some cases double the lifespan of that roof surface.

Kevin: Absolutely Dave. I’m always amazed whenever we do maintenance on a roof, or do a change out on a green roof, once we pull up the roof, or the waterproofing layer, the underlying roof system looks like brand new, so we keep the ultraviolet rays off the roof, and there’s no telling how long it will extend the workable life of a roof system

Dave: Ok moving on to number eight, let’s talk about some of the energy savings that green roofs can bring, and how they can help you reduce your heating and cooling costs.

Kevin: Dave, this is exciting.  We just installed some thermocouples and are starting a temperature monitoring field trial for them on a number of green roofs here at Metroverde. And what we’ve seen so far, I’ve got it published on my blog, I believe there’s a link on your website to my blog, is that the asphalt roofs quickly gain heat during the day and jump 40-50 degrees hotter than the green roofs, so over time, it you look at that temperature curve you can see green roofs really do help moderate rooftop temperatures which, in turn, helps with the urban heat island effect and definitely energy savings within the building.

Dave: Yeah, I was checking out the research up on your site – do you want to give the name of your site again?

Kevin: its kevinsonger.blogspot.com.

Dave: And this is where Kevin puts up a lot of his research from green roofs that he’s installing with his company and, it’s really amazing to see the graph they have that shows how quickly those asphalt roofs heat up, and how having a green roof really reduces that curve and has a much more gentle heating up and cooling down throughout the day, and what that means for the bottom line is less money spent heating and cooling your home.

Alright, so benefit number nine of installing a green roof is the tax and zoning incentives that are available in many states and counties around the country

Kevin: This is exciting, Dave. For example, the city of Port Orange here in Florida has a one to one credit they allow if you don’t have the required amount of landscaping on your building site, you can put that landscaping on your roof. And this makes projects work, whereas they might not otherwise, so lots of benefits – check back I know you have a tab on your website that is a reference for some of those benefits, but check with your local authorities.

Dave: Yeah, we are going to have that link in the quick tip at the end of the show, which is a link to a site which has a very handy compilation of all the different zoning and tax incentives that are in place around the country. So make sure you stay tuned for that at the end of the show.

And now, let’s go on to number ten – so the top tenth top benefit of installing a green roof is that it reduces the urban heat island effect, and creates a microclimate around your building – so what is the urban heat island effect exactly?

Kevin: Dave, it’s just simply keeping the area cooler. Black asphalt roofs typically run 150-160 degrees Fahrenheit during a sunny day.  Green roofs 80-90 degrees, so your area is kept cooler, your building is cooler, and hence the entire city is cooler.

Dave: Yeah there’s some really fascinating research on that, we’ll have that in the show notes about how green roofs – even just one – can really change around, create a microclimate around the building and make the area much more pleasant place to live.

So, as promised those are the top ten, there are many more, which I’m sure we will cover in subsequent episodes, and they make a pretty compelling case for at least starting the research to see if a green roof might be right for your property or if you live in a condo building like me, staring to take to your neighbors and spread the world a little bit.

Let’s move on to the quick tip, which I mentioned earlier. If you go to a page on my site which is www.greenroofplan.com/resources and look under “websites” at the end, there’s a link to a site that gives you a round-up of all the different legislation, policies and tax incentives for installing green roofs in your area, so you can go and check to see what might be available to you wherever you live.

Kevin: Green roofs are addictive, they really are.  Once you start, it’s hard to quit.  There are just so many benefits, and I look forward to discussing, vetting through some of the ups and downs of green roofs with you in future podcasts.

Dave: Yeah, and I hope you all enjoyed the podcast, this is it for us for today, but we’d like to encourage you to please leave us a comment on the post and let us know what questions or topics you’d like us to cover in future segments of the podcast. And make sure you tune in next time where we will talk about the different types and variations of green roofs.