I am surprised how few residential green roofs you see out there. Certainly the trend toward sloped roofs hampers this strategy a bit, but in may climates, the possibility for the green roof in a residential application are feasible.

Renovating a flat roof house, think about adding a green roof. Doing an addition to your house, think about a green roof. While the residential context (especially the suburban version) isn't subject to as much of the heat island effect as its urban high rise cousin, any reduction in surface water run-off or heat radiation from dark surfaces helps the environment.

Anyone have any ideas or detractors to a movement to push for green roofs of residential structures?

lilly. This sounds like one of those ventures that is all pie in the sky and has little appeal to the bulk of home consumers. I could be wrong, but the added cost of installing a green roof is just too high for the average home buyer, not to mention the design requirements are so much different than what you usually see in the suburban context. The high pitched roofs would have to go and contractors would have to consider a whole new set of loads and forces.

I think it would be nice, but I think for now its a niche market.

I've seen a few out there, but it is a very hard-sell to convince a home owner to flop down that much extra money for a mostly philanthropic investment. That is not to say that a green roof has no benefits. As you know it will have a heat loss/gain mitigating effect and also a reduction in run-off, but for the most part this isn't like adding solar panels or a geothermal heat pump. The benefits are more subtle.

The other component here is the fact that the style of house is drastically different from what most people see as a home. No high pitched gables or super-complex roof lines (I think I will do a post on the latter at some point). Its just a very hard sell to the standard home buyer, but to the greenie, this is a great source of conversation even if not installed.

How much does a residential green roof typically cost installed? Wouldn't it pay itself back at a similar rate to something like a PV system? I know it may seem weird to many green newbies that putting grass on your roof would be a good choice, but I really think it's a missed opportunity.

lilly, you may not be surprised to learn that there are many green technologies that are flowing into the mainstream of commercial construction that have little to no impact in the residential markets and especially the single family home. For many of these products and technologies its because they just are applicable and others are slow to take because they are expensive. I think the green roof is one of those that spans the gap. Its usually not applicable and when it is, its sometimes too expensive.

I get that there is this overwhelming trend to have high pitched roofs and that in some areas the code actually requires that pitched roofs be steeper than one might think is necessary. I was just wondering why there isn't a defined movement to start constructing homes with green roofs. Think of the reduction in impervious surface area if a large neighborhood was all green roofs. That would be amazing.

lilly, its not overlooked, its just out of the reach of most home buyers. A flat roof is more expensive and more maintenance prone. In a larger commercial application this cost is easily folded into the larger cost of the building. A home is not necessarily the right place the express the green roof. For some it works, but for the vast majority, this just isn't feasible.

Selling the green roof or anything non-traditional is difficult to do. Most people have this idyllic image of what the home is and that is what they expect. It takes a special client right now to allow the designer, architect or developer to explore non-traditional means of design and construction. Hopefully that changes but until it does, I am just happy to get the few opportunities that I do to "go for the green"

GHD, with you position in the industry, do you see a shift in what people are looking for or their willingness to try more innovative approaches?

Have you had a client as for a green roof, even if they didn't know what that entailed?

People are scared of flat and low-pitch roofs. They think they leak. They think they cost too much. They also don't see how they fit into the tract home landscape with high pitch, wasted space roofs. I am all for the residential green roof, but it will take much any and a long time to overcome decades of residential building trends to make is more normal.