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marson marson is offline
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Default Flat roof materials

On Feb 20, 1:56 pm, Robert Allison wrote:
wrote:
I've looked in to this and it looks straightforward enough that me and
a friend could replace my rubber roof with new EPDM.


My question is that I know it has a slight pitch to direct rain water
towards the drain, but what was used to shape the roof? When I bought
the house the inspector said something about foamboard? I was
thinking of using wedges to nail to the top of the joists that the
underlayment will lay on...It would be easy enough to create the
slight pitch that way.


Mike


GAF and many other companies make foam board insulation and wedge
shaped foamboard to provide slope. We use it all the time on
commercial buildings to form the slope. Either that, or the roof
is framed using standard roof joist systems which are then built
up with wedge cut members to slope the roof, which is then
decked. The foam board can then be used for insulation and the
roofing material goes over that.

Here is an example of sloped foamboard:

http://www.gaf.com/Content/Documents/1040.pdf

--
Robert Allison
Rimshot, Inc.
Georgetown, TX


Robert is right as usual. Note that usually you have to screw down
coverboard over the foam (otherwise the contact cement will melt the
foam). coverboard is just 1/2" fiberboard held down with washers.
You could do it with wedges as you suggest, but then you would have to
sheath it with 3/4" t and g plywood--at least that is what is specced
on the flat roofs I do. Might find information he
http://www.watertighttech.com/home.shtm