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Question DetailsAsked on 11/22/2013

cost to put foam roof on top of flat tar roof

painted flat tar roof want to cover it with a foam roof

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3 Answers


I would talk with a few roofers before you go ahead with this or with bids - I think you will find most do NOT recommend foam for a flat roof. Generally, you need a good crown coered with an elastomeric epoxy for a foam roof to work without absorbing a lot of water, which can collapse your roof system. For a true flat roof, built-up (tarpaper and tar) and variouos forms of membrane roofing are the recommended solutions, though as I am sure you realize, any flat roof is a bad roof in the long run.

IF you are able to conert the flat roof to a sloping roof, assuming that would not overload your support system, that would probably be the best overall solution - either with an intermediate roof truss system, or with tapered foam panels, overlain by the waterproofing layer.

Answered 6 years ago by LCD


I was looking at your question as a possible reference to answer another question, and noticed I may have not been totally clear. When I said foam is not recommended for flat roofs, I meant a sprayed urethane foam roof. Foam board, especially if wedge-shaped to give some slope to the roof, COVERED with a waterproof membrane or even built-up tar roofing is a standard application and not what I meant to avoid.

Answered 6 years ago by LCD


Foam roofs can vary in pricing depending on contractor and material used just like every other roofing process , and in response to the "don't put foam on a flat roof" I'm sorry but it seems you are mis informed or have had a bad experince with foam, closed cell roofing foam does not absorb water , you may have seen some one put open cell on a roof which is insulation not roofing foam , foam roofs are some of if not the best flat or low pitched roofs available ,

cost can can range between 3.00 to 6.00 per sq ft , depending on job/size type of job top coat used etc etc, I recommend contacting a contractor in your area and ask questions and for references , I've witnessed plenty of bad shingle or tar paper roofs , that does not mean the roof type is bad just bad contractors

Source: RooferMan

Answered 5 years ago by Jwilson84

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