Flat Roofs - Which Materials to Use?

shw001September 9, 2011

Any opinions on flat roof materials? Four types are most prevalent:

1. Torch down (also called modified bitumen?)

2. EPDM: For practical purposes, only available in black, since the white has a much shorter warantee.

3. TPO: Available in several colors

4. PVC: Available in several colors

How big a difference in heat gain will the color make? (black vs. white) This is in Maryland, near D.C., Zone 6B.

This is for a 360 square foot flat roof with a very minor slope (1/8th inch per foot) and about 8-inches of fiberglass insulation under the plywood deck. No pipes, skylights or other protrusions through the roof. On one side, it must be adhered to a brick wall; the other three sides have gutters.

Are the advantages of the rubber/plastic materials over torch down exagerated? Most local roofers who are highly recommended around here use torch down, since it is what they are experienced with it and can do a proper installation. Prices vary tremendously.

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"EPDM: For practical purposes, only available in black, since the white has a much shorter warantee. "

Firestone, the largest maker of EPDM, does not offer any warranty on residential work.

They have aimed their product solely at the commercial market.

The workmanship of the installation is more important than the material warranty.

    Bookmark   September 10, 2011 at 10:41AM
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I agree about the installation being more important. I am using the warrantee as a sort of guage as to how this material is likely to hold up, rather than as an actual item in the contract. A long warantee is one reason PVC and TPO sound so appealling. AND one contractor I spoke with charges only anout 15% more for PVC over EPDM.

    Bookmark   September 11, 2011 at 4:28PM
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I just got what seems like an unusual bid from a local contractor with a good reputation. Although EPDM and PVC are better, this is tempting because the installer is good and the price is less than half that of the other materials. What do you think?
1. Leave the tin roof in place
2. Attach 1/2 inch rigid insulation over the old tin roof
3. Attach 3/8 or 1/2 inch of some type of sheathing board over the insulation
4. Adhere the torch down to that surface. (GAF smooth surface)
5. Paint the surface with aluminum paint, which he says needs to be painted only every 7-10 years.

roof has very small slope (1%, or 1/8 inch per foot)

Is this installation OK?

    Bookmark   September 13, 2011 at 1:27PM
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