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I bought a house several months ago. It was remodeled 20 years ago and the built on top of the old house. Our gardener accidentally left the hose on in our yard above our garage for 30+ hours at a spot above our garage (the yard on that side is level with the roof of the partially dug in garage)… and we found water in the garage. It was obvious to me that the water soaked through the ground and into the garage through the foundation.

We pulled the drywall and found windows in the concrete walls, with dirt on the other side. So I’m guessing at some point this was a concrete wall that had windows… and then they filled in with dirt to raise the yard to the roof of that wall. Maybe there’s wood or something on the other side to keep the dirt from breaking that window… but the water leaked in.

We can’t easily dig it out from the exterior since there is a sidewalk and concrete stairs immediately above it.

Options we are considering:

  1. tear up the sidewalk, dig down to windows, fill in the window with framing or masonry and waterproof the wall. Expensive, big job.

  2. just dry it all out and put drywall back over it…. If we don’t have a flood or garden hose left on for 20+ hours maybe it won’t happen again

  3. try and fill the window from the inside. Maybe if it’s mostly waterproof we’d be ok since the water could escape elsewhere??

There’s also a crack in the concrete wall from the window down to the floor.

Other?? Appreciate any advice. enter image description here.

Pictures are of the sidewalk above the wall with the garage “window” and the window itself taken from the garage.

enter image description here

enter image description here

FreeMan
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lcb boulder
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    Option 1, otherwise you **will** be doing it again. – Solar Mike Jul 28 '22 at 09:33
  • You say you also have a crack in the wall, so two possible ways for water to get in. Wood and drywall do not like to be wet/damp. Dark(inside walls) damp places is where mold likes to grow. Option 1 is a pain in the neck/back, but is proven to work for a long time, maybe forever. Places that get flooded every hundred years are finding those hundred years are becoming every five or ten year floods. – crip659 Jul 28 '22 at 10:20
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    On option 1, use masonry, not 'framing'. I would use concrete. You can use your interior framing as concrete form support. One question: if this area to be used for bedroom, do you have egress if you closed this off? If not, you want to make this a functional egress. – peinal Jul 28 '22 at 11:37
  • My first thought: "Do it right or do it over". Yes, it's expensive and yes, it's a pain, but better to go through the expense and pain once than every few years. Or, as it seems to have been at many of my employers, "there's never enough time (or money) to do it right the first time, but there's always plenty of time (and money) to fix it later". – FreeMan Jul 28 '22 at 12:50

2 Answers2

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The best and proper way would be option 1. Remove the sidewalk, dig down, concrete the hole closed (probably want a few sticks of rebar into the existing concrete), parge, backfill, and pour a new sidewalk.

Although... I would be greatly tempted to gently remove the window from the inside, compact the soil away from the opening until you have enough room to use concrete block and mortar to fill it in until there is only one block left, let dry, fill the backside with closed-cell spray foam (assuming a small gap <1"), and then put in the last block.

NOT as good as a real parge, but whoever did that almost certainly didn't parge the rest of the wall that is below grade. If it were my house and in an area where you don't normally get flooding/ponding, it seems like a fairly inexpensive way to likely resolve the issue.

UnhandledExcepSean
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0

I'm going to give you an option 4 (or option 1.5 if you will).

The problem

Even without windows (but much more likely when they are present), water that is allowed to sit next to a concrete wall is going to seep through. That tar that builders spray on the outside is not a perfect water barrier (and it opens up along with the cracks when they inevitably happen). There are adhesive EPDM rubber barriers that you apply to the outside of concrete or block, but you need to excavate the entire foundation to properly apply them, which is time-consuming and expensive (believe me - I have done it), and that's if you're just excavating some lawn or flower beds - hardscapes add an additional pain point (more on this later).

The better option over sealing against water is giving it somewhere else to go.

Also remember that water moves underground not just vertically, but laterally as well. Finally, water will follow the path of least resistance.

The Solution

French drain.

But wait - don't we need to remove that sidewalk? The answer is no, as long as the sidewalk is mostly non-porous (i.e. not intentionally porous - all concrete slabs are a little porous). Consider that hardscape to be a "roof" over the soil underneath. The only way water can get there is by seeping laterally or seeping up vertically from below. What the french drain does is artificially lowers the maximum water table by providing an outlet for water that reaches it.

What I would do in your situation is dig a trench along the outside edge of your sidewalk and staircase. Make the depth of the trench at least a foot deeper than the bottom of your window opening. If you want to be a superstar, go all the way to the footing level. Line the bottom and sides with geotextile fabric and bury a 3 or 4 inch perforated drain pipe at the bottom. That pipe should run to a place where the water will be safe to outlet (in my situation I had a flat lot and had to bury drywells in order to have somewhere for the water to gravity drain to). I can see from your picture that you have a pretty decent slope there, so you might be able to just daylight that pipe at the bottom of the staircase. Backfill the trench with 2-3" river rock or something similar. The point is for there to be lots of airspace between the rocks - i.e. nothing with fines and nothing with lots of flat faces to encourage compaction. Wrap the geotextile fabric over the top to create a "tube" of stones with an embedded pipe at the bottom. This will keep silt from clogging it up. Cover with gravel, soil, or whatever you like.

What that does is allows any water that reaches either the sides or bottom of the trench to easily seep into the drain rock trench, into the pipe, and eventually out the end, effectively lowering the local water table to a level that is below your window opening.

This MSpaint cave drawing that looks like a 4-year-old did it illustrates what I'm describing. It's only 2D so it doesn't show the slope of the trench, but you will want to slope the trench bottom (and the drain pipe) down your stairs to drain the collected water. enter image description here

Chris O
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  • Really appreciate this. Smart. – lcb boulder Jul 29 '22 at 02:55
  • I was looking online and several sites recommend the maximum depth of a French drain be nice more than 18-24 inches. Thoughts? Ii would need to make it probably 4-6 ft to get below th window. Would that crush the perforated pipe with all that? Or cause other issues? – lcb boulder Jul 29 '22 at 03:12
  • Years ago when I had a house that should never have had a basement but did (essentially on a flood plain but lax permitting requirements), we had huge problems with leakage. I excavated the whole thing and placed a perimeter drain all the way around. The drain was over 8 feet at its deepest and we had no issues - lived there another 11 years after. – Chris O Jul 29 '22 at 16:14