I've just had a garage roof laid with EPDM rubber bond. I expected this to come in multiple pieces, but the roofer has used 4 pieces. 2 long strips on either side, then 2 half-length strips to fill-in the centre remaining gap.

I have serious concerns about the longevity of the roof as a result. The roofer claims his supplier gave it to him like that telling him it was "easier" despite him telling me that it was ordered as a single piece. He claims this is "glued" using the same methods the factory/supplier uses to stick the whole sheets together in the first place, so is effectively identical.

Should I be concerned about the long-term longevity of the roof? What would be your advise to tackle this problem with the roofer? No money has been exchanged yet.

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    Hello, and welcome to Home Improvement. A picture of the joints might help. And, you should probably take our tour so you'll know how best to participate here. Commented Aug 1, 2019 at 11:49
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    If I ordered a single sheet and it was available I would want what I paid for. Membrane roofs if properly lapped and glued will be fine but that is another place for a possible leak. Factory splices are done in a controlled environment not out in the open so even though the same adhesive is used it is not the same. I would push back on the company to at least get some $ back or have the entire job redone.
    – Ed Beal
    Commented Aug 1, 2019 at 15:03

1 Answer 1


It's perfectly possible to have a lap seam in an EPDM rubber roof.

The important thing is that the lap seam is horizontal, with the upper piece overlapping on top of the lower piece.

The strength in a rubber roof is in

  • the fact that no one has destroyed the rubber chemically by attempting a repair with random cheap roof-patch materials from the building supply, which invariably contain tar or other chemicals incompatible with rubber roofs

  • how well it's glued down to the substrate

  • how well the seams are glued.

All of these can be well done, to answer your question. (But the first one is up to you.)

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