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Alongside my house is an old coal door that was never properly sealed. Some caulk was added around the metal exterior door, and a piece of plywood nailed over the interior opening (more to keep out critters than water, I believe).

As you can see from this exterior view, there's not much I can do about removing the door itself:

Exterior view of coal door

But on the inside there is a cavity that could be filled in somehow:

Interior view

The framing inside here was metal -- it's mostly rusted out now -- and there is a little bit of daylight making its way through. This is very obviously not watertight.

The house has a brick and mortar foundation. What's the right way to seal this up to keep water and critters out?

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How do you feel about excavating the exterior through—what is that? Asphalt?—down below the level of the door? –  wallyk Sep 3 '13 at 18:18
I'd rather not at this point... the asphalt driveway was just re-sealed before we bought the house. But if that's the only option, I'd consider it. –  Joe Shaw Sep 3 '13 at 18:26
Personally, I'd fill it with >2lb polyurethane foam. Most 2lb density foam is considered open cell where higher densities are closed cell and will provide a much better long term absolute seal. That also relies on using a 2 part mix cured in the hole, not a foam block cut to size. –  Jason Sep 3 '13 at 21:55

3 Answers 3

Well, I would suggest excavation down below the opening taking out the coal door, install a small window and make the area that was excavated a window well. I have known some people that have done this very thing and it works great. Does it leak in a heavy rain since they laid the asphalt above the opening or is it graded away from the house?

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I like the idea, but unfortunately this is right against our driveway (hence the asphalt) and I'm not sure I can spare the space for a window well there. The grading is pretty good and there certainly isn't a rush of water in that way, but there is some daylight and water making it through the top part of the door. –  Joe Shaw Sep 30 '13 at 15:41

As you already know there is water getting into there, if you only seal up the inside to make it look better you will have water collecting between the door and your seal. You don't want a pool installed in your wall.

To do this properly you really do need to excavate the outside remove the door and metal frame (if there is a steel load bearing piece across the top I'd recommend leaving that in and if there is a rain catch on the outside that could be left, but it doesn't look like there's either from the pictures). Patch the hole with material that functionally matches the foundation wall. Water seal the patched area then once it is dry back fill where you excavated. It would be good to make that area right against the seal a little higher grade when you fill it in than the area around it to help the water drain away and reduce infiltration.

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I'd fill the hole entirely with low expanding spray foam.

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