I recently purchased a 1937 house with two decks on the upper floor. One of the decks has a draining issue. While hosing it off, I noticed that a small puddle accumulates near the middle of the deck. The puddle left over is very shallow (maybe on the order of 3mm or so), but I don't like the idea of any standing water above a living space. I'm not sure the material that was used for the deck; it is white and has a rubbery feel to it.

So I trying to figure out how to get a bit of slope, or at least figure how to ensure that there isn't any water damage in the future. I seem to remember hearing about some kind of foam that could be used to build slope and seal the deck, but I can't find details.

What material should I use to introduce slope to the deck? What should I use/do to ensure that it doesn't leak if a slope isn't possible?

Thanks, Erick


I've added a couple of pictures, but I'm not sure how helpful they will be to know what the surface is. The carpet was in the middle of the deck, and probably helps keep the water from pooling in one place. I'd still like to know how to maintain a deck like this, as water leaks are the last thing I need.

Above the deck view Close up

  • I had tapered insulation installed a few years ago on a flat roof on a house I used to own. It was installed on top of the existing roof and then new hot rolled asphalt roofing installed over that. The slope was about 1" in 4ft. I don't know how this would stand up to being used as a deck to be regularly walked on though.
    – brhans
    Jul 24, 2017 at 19:06
  • 2
    Without knowing anything about the structure of the deck I can't see how anyone could answer this. Photos or a detailed description seem like a requirement.
    – isherwood
    Jul 24, 2017 at 19:15
  • 1
    It sounds as though the white rubbery coating may be a bit more contemporary than 1937. It could be an elastomeric coating, typically applied in liquid form with care taken to ensure a complete and contiguous surface. If another layer is created over this one, you may create locations in which water can collect and not evaporate.
    – fred_dot_u
    Jul 24, 2017 at 22:21

1 Answer 1


You need to know exactly what the surface of the deck is, and probably what the structure under looks like. Otherwise, you'll probably only make the problem worse.

But without that info, 3 mm is not much. You didn't mention the other 2 dimensions, but a few minutes of sunshine will probably dry that up. I probably wouldn't do anything at all.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.