Flat Roof Materials

shw001September 8, 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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brickeyee

Use black and cover it with gravel.

You may need an extra layer on top of the EPDM to protect it if the rocks are sharp.

    Bookmark   September 8, 2011 at 6:27PM
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shw001

Thanks for quick response Brickeyee. However, this is a residence and there is no border around roof to contain gravel. Also, I or others may occasionally walk on the roof to clean gutters and service roof above it, paint house, etc.

    Bookmark   September 8, 2011 at 10:54PM
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brickeyee

Add that border as you put down the EPDM.

It has to be glued down, fastened down, or ballasted down.

With the correct layer on top of the EPDM (often non-woven rayon type material) before the gravel is pout down you can still walk on it for maintenance purposes.

    Bookmark   September 10, 2011 at 1:31PM
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shw001

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 1:23PM
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