pocster

Edpm at edges

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16 minutes ago, JSHarris said:

If it were me I'd want the EPDM well-protected from damage.  Having it encapsulated under concrete makes it pretty much bomb-proof, and far less likely to be damaged than having it partially exposed.  If it does get damaged in the exposed areas then I would guess that sods law says that the whole membrane will need replacing, including the area under the concreted bit in the middle, so just as much work to fix.

 

There's no difference between an encapsulated roof membrane like this and the DPM under our concrete slab, that keeps the damp out.  If our DPM fails then the whole house has to come down in order to fix it, as the slab runs under our walls.  What's more, our DPM is a much thinner sheet of polyethylene, nowhere near as robust as a 1.5mm layer of EPDM.

If exposed edpm gets damaged I thought it could be fixed / patched ?? 

After all that was the original plan on the upstands 

Edited by pocster

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3 minutes ago, pocster said:

If exposed edpm gets damaged I thought it could be fixed / patched ?? 

After all that was the original plan on the upstands 

 

Depends.  If the damage happens near the concreted part than you may well not have a large enough overlap area for any patch to seal properly, which may mean taking up the concrete.  It's hard to see how a membrane embedded in concrete could get damaged, especially given the flexibility of EPDM.

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11 minutes ago, JSHarris said:

 

Depends.  If the damage happens near the concreted part than you may well not have a large enough overlap area for any patch to seal properly, which may mean taking up the concrete.  It's hard to see how a membrane embedded in concrete could get damaged, especially given the flexibility of EPDM.

I take your point . Most likely failure point though must be edges / flashing . Also the stilted solution means no water at skylight level - skylight never gets swamped in water . Trying to solve multiple problems with this scenario 🤪

Edited by pocster

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You don't have sitting water on your DPM. Totally different scenario. It's to stop damp coming up not water getting down through it. If having the membrane under concrete was a good idea they would do it on commercial roofs and I've never seen it done in 36 years.

Edited by Onoff

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