Should we get a foam roof?
July 28, 2008 11:29 AM   Subscribe

Should we get a foam roof?

We're buying a house that has an old tar and gravel roof that needs replacing. We've got a quote for something called a modified bitumen roof but I keep hearing about foam roofs.
They are supposed to last the lifetime of the house and add a lot of insulation value. Anyone have any experience? Can you recommend a good contractor in the SF Bay area?
posted by Wolfie to Home & Garden (9 answers total) 1 user marked this as a favorite
I looked into foam roofs a little while ago to replace my built-up asphalt roof. The basic deal is that they spray polyurethane foam over your existing roof, then cover it with a protective coating (epoxy, i think), because poly foam is broken down by UV light. It's more delicate than your current roof, so you can't really walk around on it much, but it can be repaired a little more easily than built up asphalt. Another disadvantage is that there aren't a lot of installers and only some of those installers will do residential roofs, so the prices might not be as competitive.

So, it's definitely worth looking into, another option is an EPDM roof, also known as a rubber roof. It's large sheet of rubbery material thats bonded to either a layer of insulation or plywood decking. They may or may not have to tear off the existing roof, which may also be necessary with the foam roof.
posted by electroboy at 12:22 PM on July 28, 2008

Just a note: Modified bitumen is pretty much similar to the "tar and gravel" roof you already have. Bitumen = asphalt, and it's used to impregnate and waterproof layers of roofing felt, which are then shingled up over each other to make up "built-up roofing", which is very common for flat roofs.

EPDM is a type of single-ply (i.e. not built up in layers) roofing. There are a bunch of other kinds--I've worked previously with TPO. Those types of roofs are typically installed over a layer of rigid insulation.
posted by LionIndex at 1:00 PM on July 28, 2008

FWIW, I have an EPDM roof that is failing after 10 years. This may or may not be typical but I have had four different roofers tell me it is (maybe they just want my money). All of them wanted to replace the EPDM with something else. Three of them wanted to use bitumen and the fourth wanted to use PVC. The PVC roof comes with a 25 year warranty.
posted by toomuch at 1:01 PM on July 28, 2008

FWIW, I replaced a built up roof (good for 10 years in the climate enjoyed in the burbs around NYC) with an EPDM roof 25 years ago. Other than a coat or two of fibrated aluminum paint every 10 years as maintenance, the epdm roof is only coming the end of its useful life after 18 years.
posted by Fupped Duck at 2:54 PM on July 28, 2008

I am also considering a foam roof. It was suggested to me by a design-builder who seems to be committed to green construction. His company was out of the price range for my remodel, but he was very helpful and gave me some good information. Because I have a flat roof, it is prime for the a 'cool roof'. It is said to reduce the amount of heat on the roof, which impacts the amount of heat coming into the house. The foam insulates and the coating reflects the sunlight. Last week, I began searching for information. I found out that there are rebates in California for 'cool roofs' (check out PG&E in the Bay Area and the GoSolar site). I think that you need to have central air to qualify for the rebate. I found a contractors website from the Bay Area that may be helpful for you(unfortunately, I am in S.CA). Search " I am also looking into solar water heating. The federal government has a 30% tax credit, for up to $2000) for that but it is only valid until the end of the year, unless the extension gets approved by the Senate. Everything I am reading, so far, makes the foam roof seem to be a great choice for flat roofs. The energy savings makes the pay back for the roof about 3 - 5 yrs (from what I have read...) Good Luck. I am pretty sold on the idea, now I just need to find contractors.
posted by maidmargoe at 12:58 PM on August 1, 2008


What kind of prices have you been seeing?
posted by electroboy at 6:23 AM on August 5, 2008

I've got three quotes - one for the traditional roof at around 11k. Two foam roof quotes - one for around 14k and one for 24k. It seems the foam gives you an entire R level of insulation - which is great. My biggest concern is the aesthetics. It's a light colored roof. A dark roof blends in with the house - a bright white blanket will be noticed by the neighbors. Hopefully they won't mind.
posted by Wolfie at 10:13 AM on August 5, 2008

What's your square footage? I'm coming up on the recoat/replace time on my built-up roof and it seems like a good time to consider something like this.

Also, from what I've seen, poly foam is around R=6-7 per inch, with 2 inches being about the standard. The white roof may stand out, but it will definitely save you money by not absorbing as much heat.
posted by electroboy at 10:40 AM on August 5, 2008

we're looking at a total (house and garage) or about 16 squares. Our new house is in a nice zip code - I have a feeling we're getting a little mark up based on that.
posted by Wolfie at 3:59 PM on August 5, 2008

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