Roof delamination

hddecker wrote:

I would think that he did that so the epoxy didn't glue what ever he weighed it done with to the roof.

Look strange to have a fifty pound block of cement unuder the EPMD.

Yeah, well... Sounds like he glued 2 delaminated layers of ply together - the bottom intact one and the top one that delaminated from the bottom one, but was "stuck to EPDM".

And then put 50 lbs on wax paper on EPDM - this part makes some sense as you need a bit of pressure to keep 2 layers of ply together when they are warped.

The first part - filling the void with epoxy - doesn't sound like a good repair, it's more like a "sealing the rot". The top layer of ply had separated from the bottom for reason no other than rot. Solids turn into cr-p and emit gases that are pushing 2 layers apart. Other than cutting the whole area out, I don't know what would be the best method though. Boaters in such difficult places use some deep penetrating "Git Rot" - I suspect it's a kind of low-viscosity epoxy. A low-viscosity epoxy is a good thing anyway - like West System marine epoxy. A regular 1:1 epoxy from Home Depot would not be my choice here.

Btw, I'm surprised to hear about "plywood". Over the last decade or so manufacturers mostly have been using a lower grade product called OSB - oriented strand board. It can delaminate too, of course.

Almot wrote:
So you made sure with wax paper that the EPDM sheet would not adhere again to plywood? Why?

I would think that he did that so the epoxy didn't glue what ever he weighed it done with to the roof.

Look strange to have a fifty pound block of cement unuder the EPMD.

So you made sure with wax paper that the EPDM sheet would not adhere again to plywood? Why?

Thanks all again. I ended up cutting 3 sides of an 8" square piece and then peeling it up to see what was going on. About 1/8" of plywood had separated from the plywood below and the EDPM roofing was still stuck tight to the 1/8" piece. All the plywood looked strong and intact except for the 8" delaminated part. There was no dry rot at all and I could not see where any water had come from any direction to cause this. There are no seams within a couple of feet of the area. I ended up filling the area with epoxy, put wax paper on it and weighed it down overnight with about 50 lbs. of weight. I then covered the whole area with Eternabond tape and the used Dicor lap sealant on all the seems. If this doesn't work I'll always thought it should've.

Doesn't Eternabond make a double sided product?

scroller95969 wrote:
Thanks for all the answers. What kind of adhesive should I use to reattach the EDPM roof to the plywood? Would the 3m spray adhesive work or will that attack the EDPM roof?

The 3 M probably has a petroleum distillate in it so it will definitely attack the rubber.

Check the plywood with a moisture meter, the ply may feel dry but could have moisture that you can't detect. Ensure that you push the pins through the top layer of veneer.

I would not use staples on the roof, they tend to work lose and will find their way back out through the rubber. I would make a slit in the top veneer and squeeze a good quality marine glue in the slit. Cover with apiece of plastic so any glue that squeezes out will release, then weight it down and let dry.

Then use you eternabond or ?, and then cover with your roof coating.

A good source of DIY info on rubber roofs is the Dicor web site, get it straight from the horses mouth.

Thanks for all the answers. What kind of adhesive should I use to reattach the EDPM roof to the plywood? Would the 3m spray adhesive work or will that attack the EDPM roof?

I think if it were me, I'd cut the 8" X, check to make sure all is good, not rot, and then Lay it flat, tape with eternabond and then cover with dicor. Not a fan of the staple through rubber idea.

Hard to tell whether there's staining or not through a 1-2" slice. That's why I'm trying to decide whether to cut an 8" cross on it so I can see better or to just staple it down, seal and watch it.

Every once in a while I see a piece of plywood with a spot like that. It looks like there was not enough glue or something. If you can't see any water staining then I would just fix as you describe and then watch it.
Good luck,
Scott