April 29th, 2009

Ecoroofs

Ecoroof Grant Program

This year, the city of Portland’s Bureau of Environmental Services (BES) started a grant program to encourage the creation of eco-roofs within the city.  To do this they are offering grants of up to $5 per square foot of vegetated area.  Fortunately for us, our construction schedule coincided nicely with the first grant cycle and we were awarded one of the first grants along with about twenty other projects.  Ours is unique among the first group in that we are the only new residence with 100% ecoroof coverage.

The primary concern for BES is the stormwater management aspect but that was only one of an assortment of reasons that we decided to go with eco-roofs on our house.  Eco-roofs tend to decrease the need for other stormwater management facilities by around 50%, they can reduce your need for heating and especially air conditioning, they last longer and can reduce maintenance costs, and they’re nice to hang out on…  But for various not very good reasons, they aren’t standard construction.  Despite the advantages, they do involve more up front construction cost than a conventional roof does and builders and developers have few incentives to pay more for the better roofing system (we will go into this in depth in future posts).  The intention of the grant program is to offset these additional costs – $5 per square foot is roughly the difference in cost that one can expect when building an ecoroof – and by encouraging the construction of more ecoroofs within the city, BES can recuce the load placed on our public infrustructure saving money for the city of Portland.  Additionally all projects being built through the grant program will become case studies for the city, our methods, successes, and failures will be used to help inform future ecoroof builders so that it becomes easier for them to build responsibly.

Our Ecoroof

From the beginning of our plans to build a house, there was no question that all of our roof area would be vegetated.  There really isn’t much reason not to do it.  Many of the decisions we made in the design of our house were dictated by building in efficiencies that would allow us to make the most of our relatively small combined income.  We knew we were building a small house that would require outdoor space to become very integrated into our daily life and the roof is a potentially occupied area as big as the house that would allow us to shrink our house down.  Additionally, one of our goals from the beginning was to reduce or even eliminate our need for large heating and air conditioning systems.  The increased insulation and thermal mass we gain from the ecoroofs help us increase the comfort of our home while decreasing our monthly bills.

With this already decided, we were very excited when we heard BES had begun its ecoroof grant program…  We are stretched as it is to build our house and any help we can get is much appreciated.  After submitting our grant proposal, we were contacted by Tom Liptan with the Bureau of Environmental Services to discuss detailing of our ecoroof.  I suppose this is more evidence that the ecoroof program that BES has started is very needed, but when detailing this, I found very little information about the logic behind the layering of your ecoroof.  There were consultants out there that we could pay to design our ecoroof, and there were expensive systems that we could order, but not a whole lot to inform someone trying to learn it themselves.

As part of our grant proposal, we submitted the detail above which specifies a drainage layer above torch-down roofing membrane.  Above that is our root barrier with soil on top of that.  I had been concerned about roots clogging the drainage layer, but after speaking with Tom we learned that there tend to be issues with layers shifting and if the root barrier is above the drainage layer it can compromise that barrier.

Ecoroof Vendors Fair

This last weekend there was an eco-roof vendors fair held at the Doubletree Hotel near Lloyd Center.  We were given a heads up beforehand by the people running the ecoroof grant program that for a project of our scale, we could probably do a better job for less money if we do everything ourselves rather than buy a system but that it would still be helpful to go knowledge up.  This was very much the case.  Many of the systems being sold ran around $13 per square foot…  Which for certain projects can be a very desirable quick and simple alternative to bringing in specialized consultants but in our case would lead to a bit more expense and hassle than necessary.  One of the more helpful aspects of the fair was a series of presentations going on to the side of all the booths, specifically one given by Mike O’Brien of the Office of Sustainable Development about the ecoroof he built on his own house.  He built one that is similar in scope to our planned ecoroof and similarly constructed in that it is a very simple straightforward set of layers non-proprietary materials.  When building something that doesn’t have much precedent, its nice to see something like that which pretty solidly reinforced what we had been learning.

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