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Fugitive861 · 08-03-2020, 08:56 PM

6 months ago I removed an obsolete satellite dish. I used lap sealant to fill small holes and made a stainless steel plate to cover the large hole. At that time there was a hint of a soft spot. Unfortunately it has grown. You may be able to see a dashed line outlying the soft spot. The roof is rubber and I suspect epdm. How can I confirm? I’m thinking of cutting a section of rubber out about 2 foot by 3 foot, exposing the spongy spot and all the holes from the dish. Then cutting the very thin plywood sheeting out and replacing it with a new sheet. Maybe using small metal backing plates with screws to suck the edges down even with each other. Maybe fiberglass over the seam and then glue a new epdm patch over the bare spot. Then eternabond around the epdm seam and dicore lap sealant on the eternabond seam. Sound ok? Where can I get epdm piece? What is proper adhesive to glue epdm to plywood? My roof is curved Is the plywood glued to styrofoam below? Are there ribs giving the roof strength? Thanks

Rkesselus · 08-03-2020, 09:47 PM

Here is what I would do, just a recommendation. I would mark a rectangle out on the roof that extends about 3 inches past the weak spot and then cut an x corner to corner in the rubber room and make an attempt to peal the rubber back, which may turn out to be tough job, to expose the substrate and depending on what you find replace what you can. Since it is on the top and not something that has to look good I would over lap the solid substrate using a glue designed to work with what ever you find mechanically attach the new to the old using the smallest screw you can find with a tapered head to seat into the new. then replace the rubber you pealed back obtain an new piece of rubber roof material to cover the entire area and use etenabond bond tape on the edges, Basically what you planned. Fiberglass as you posted would work but the new rubber might not stick as well depending on what the substrate turns out to be. I do a lot of fibregglass work and find many times I have problems getting stuff to stick well to the resin.

Fugitive861 · 08-03-2020, 10:05 PM

Thanks. The substrate is a thin plywood. I saw it when I removed skylights, reefer vent, etc for resealing.

fasha · 08-03-2020, 10:06 PM

EPDM is usually black and almost 1/8th inch thick.Looks like yours has a reflective coating.If you can clean it off you'll get a more permanent bond. Knowing exactly what the roofing material is will be the first step.Calling the manufacturer might save some work.EPDM seams or overlaps use a special glue much like contact cement. Both mating surfaces have to be well cleaned.You can use a white gas like camping stove fuel.A roller helps to squeeze out air bubbles and mate the 2 surfaces.Some pressure is needed. Overlap the old rubber at least 6 inches and they have a caulking for the edge of the overlapping top layer.The glue should bond the EPDM to whatever you repair the soft spot with.Plywood etc. Roofing suppliers usually want to sell you a roll and a 1 gallon of glue. A roofing company might sell you a scrap piece and a half empty can. Good luck

HarryStone · 08-03-2020, 10:27 PM

https://www.youtube.com/watch?v=f5KraEQifpo

Fugitive861 · 08-03-2020, 10:35 PM

After watching video, I’ve determined our roof is epdm as the underside is black.

153stars · 08-03-2020, 10:58 PM

The plywood there may be delaminating . Does it feel like a bubble or pocket that gets tighter after you press it down, don't blow through. Looks like there was a screw hole there already . I would a small incision near it and poke with a pick or drill bit. A biopsy so to speak. See if its wet still what the plywood is like.

Fugitive861 · 08-04-2020, 05:20 AM

It feels rotted, soft, lack of integrity below membrane.

153stars · 08-04-2020, 11:41 AM

It's a pretty small spot . A wood patch scabbed in at 45 angles all the way around epoxied some screws to pull it down and brad or finish nails shot toe nail style grind any protrusions. Should support plenty of weight. What's the protrusion next to it is that on a support you may want eliminate or incorporate into repair patch. Great care and planning to not cut through too deep or drive any fasteners through of course.
There are also Smith marine epoxy that harden wood into basically fiberglass.