Self adhesive EPDM over OSB

[GaryinAshby]

Self adhesive EPDM can (according to Permaroofs blurb) be used over (new) OSB with no problems. My concern with OSB is that it isn't "smooth". Once primed & the EPDM laid, it will only adhere to the highest point of the leaves of the OSB, leaving small pockets of trapped air elsewhere. This concerns me, would I be better off overlaying the OSB with 6mm ply to give a smoother surface for adhesion? My concern is about any trapped air expanding on a warm day creating blisters.

Or am I worrying about nothing?

Thanks

 

[SurreyRoofingEstimator]

You're worrying about nothing, we use OSB with the fleece backed single ply membrane that we install as it is recomended. OK it isn't smooth but it isn't THAT rough and in fact would give a very nice key for the adhesive

 

[vinty]

Self adhesive EPDM can (according to Permaroofs blurb) be used over (new) OSB with no problems. My concern with OSB is that it isn't "smooth". Once primed & the EPDM laid, it will only adhere to the highest point of the leaves of the OSB, leaving small pockets of trapped air elsewhere. This concerns me, would I be better off overlaying the OSB with 6mm ply to give a smoother surface for adhesion? My concern is about any trapped air expanding on a warm day creating blisters.

Or am I worrying about nothing?

Thanks

EPDM is vapour permeable, which means any moisture or air trapped will eventually pass though the membrane.

 

[GaryinAshby]

Never thought of that, thanks.