# rubber directly on insulation?



## paisan (Jan 23, 2020)

hi. i have a 14’ by 26’ roof . completely open underneath i.e. not heated just over a deck. has T&G 2x6 decking. i want to put 1" xps insulation down and a epdm membrane directly on this. is that acceptable? or do i need some kind of board over the insulation
thanks
james


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## roofermann (Jul 7, 2012)

Depends on if the glue is compatible with the surface of the xps board. Why use the xps if it's exposed? Regular iso board made for EPDM would work and likely be cheaper.


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## paisan (Jan 23, 2020)

*condesation*

im a bit worried that if snow is sitting on the roof and we get a warm day there could be condensation on the underside. also the existing house has rubber and a thicker roof would help math the profile of existing house.

thanks fo you reply

james


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## roofermann (Jul 7, 2012)

Good enough reasons. They make insulation board (polyiso foam) in various thiknesses that has a glueable surface on it, you will have to talk to a pro roofing supply place to get it as the big box type stores don't carry it.:thumbup:


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## paisan (Jan 23, 2020)

yea that stuff is pricey i was hoping i could use the xps. someone told me you could if you used a water base glue. would like to confirm its ok to do.


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## roofermann (Jul 7, 2012)

I can't advise on the use of waterbased glue on xps. There are some more active roofing forums I can steer you too if interested.


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