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Amber waves of roofing?

April 8, 2010

Benefits to planting your roof:  

  • Great insulation value
  • Reduced heat gain
  • Reduce or eliminate roof drains
  • Pretty use for an otherwise utilitarian space

In our project, it also has the benefit of providing us with a ‘yard’ and garden. We have been researching green roofs in our area, trying to determine if this system would work for us and if we can afford it. At this point, we are investigating a number of options and their resultant costs, but we haven’t finalized our plans. We do now know that we aren’t going to put a huge rooftop mechanical unit up there, so we don’t have to worry about working around that. We’ll do another post on the heating and cooling investigations. The previous post covered our beginning thoughts about roofing. This one covers some of the specifics of the green roofs we’ve seen in the area.  

Bowood Farms Garden Roof

Last Summer we toured the green roof at Bowood Farms, over the kitchen for their restaurant, Cafe Osage. The roof isn’t generally open for visitors, but they offered a special tour. The roof provides the herbs and flowers for the restaurant. If you have the chance to stop by the cafe, shop and garden center, I’d highly recommend them all. A lot of what is served in the cafe is from their farm, including the Bison Burger! There is a very nice selection of well-tended plants and they are the kind you can be sure will thrive here. I love poking through the shop, too. There is always pockets of new and interesting things to see. They have an area that focuses on terrariums, which was a total flash back to childhood for me.  

Back on topic. We were talking about roofs, not food and shopping. Sorry. Did I mention they have really cute note cards? Sorry.  

The roof garden is accessible by ladder. They have a variety of plants but it looks like some things are doing better than others. Where they don’t have herbs and flowers, they have some sedum that is beginning to fill in the gaps. It looks like, in the future, the gravely growing media will be covered by green. The product brochure says you don’t need to irrigate the plants after they get established, but it looks like that would apply to the sedum variety of plants. If there are flowers and thirsty herbs like basil, we would need to hook up a hose.  

Bowood Gardens roof tour

Since the media isn’t soil, there is a fertilizer that is part of the system that needs to be applied periodically. They also recommended not planting right up to the edges of the roof. That is why the edge of the roof has a different color material. The reason for this is that if there is an issue with the roof, it is usually at the edges and flashing. The gravel makes it easier to remove the material and get to the potential problem without disturbing the plants.
The other roof we visited was at the office of the representative of this particular system, Shield Systems. The system is Cetco Greenscapes. This product does not require that the roof be sloped, which would be great for our project. The photo from this visit is from the Shield Systems website. The day we visited them it was very cold and rainy, not at all pretty or green.

Shield System's roof garden

This installation is closer to what we are interested in doing, in that it has both green space and terrace. 

Inspiring photo I found on the internet

Picture something like this with a whole lot of large stone building fragments. Yes, we moved all those huge hunks of rock over to the building. Thanks for your help Eric!  

If you look closely on the Shield Systems photo, you can see how they handled connecting the roofing to the parapet. There is a termination bar attached to the masonry wall which is above the surface of the planting. That is the condition we would expect to use. I am afraid to think of how much tuckpointing will be required, but I’m putting a hold on that thought for later panic attacks.
The next critical question was “Cool stuff, so how much does this cost?”. After some prodding and promising we know every condition is different, (Your mileage may vary) they said to use a budget of $15 per square foot. That doesn’t seem too bad until you multiply that by the amount of our roof area. Gulp.

Value engineered green roof?

It would be terrific to do the entire roof in this type of system, but it is clear that isn’t financially possible with all of the other significant work that needs doing. Really, any topic we chose to write about for this building, the scale of the work and cost is the issue. With a building of this size, we have to set some priorities and investigate phasing. They said the roofing system can be phased, but the liquid waterproofing can’t be left exposed to the sun for more than about a year. That means, it shouldn’t be left exposed at all, but we have some leeway. We are thinking we might do some combination of systems. It is also possible we might have to drop the whole idea of the planted roof and go for lots of big pots. 

The next step is to finish up our Phase 1 and 2 floor plans, get the mechanical and plumbing systems priced for Phase 1. That will tell us how much green we have left for ‘green’.
2 Comments leave one →
  1. Susan permalink
    April 9, 2010 8:06 am

    It really is a great idea. I’m sure with two creative minds you’ll find a way to make it fit your budget, and make it beautiful. I’ll look forward to a summer visit once you’re done, if I can drag your brother out of Florida…as you know, we “Southerners” don’t do cold :o)


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