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There’s a small amount of water leaks underneath a basement window (with a window well outside) in my home. I spotted the leaks several years ago, after I emptied all the stored items. Two improvements were made since:

  1. Three downspout extension pipes with 2 catch-basins diverting rainwater to the rear side of the house for disposal.
  2. A new window well was installed to improve the drainage, sometime after. All three sides of the foundation wall were sealed (grayish color) at the cove joints (visual, and clearly stated on the architectural drawing in my possession). The house was built in 1990 with a 4” perforated drain pipe lying outside of the foundation footings. The sump pump is working. I noticed the leaks seep through a small gap (~1/32” to 1/16” visual) of 4 ft in length (probably not continuous). Obviously, a portion of the seal failed at this cove joint, while the other 2 cove joints appear intact. My estimate of the amount of water leaks is ~50 ml in each occurrence, only in heavy rainfalls of 2”+. It probably happens just several times a year. Almost all waterproofing companies say that sealing the cove joints is not a good idea, while manufacturers of sealants post videos instructing homeowners how to DIY.

If you have similar experiences, would you share by answering My Questions:

  1. Should I go ahead and re-seal the leaky cove joint?
  2. What type of sealants should I consider?

Cove Joint: This website has a nice picture illustrating it. My foundation is the same without the drain pipe on the right hand side.

enter image description here

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  • including a picture of your cove joints would really help everyone out. Also, a "permanent" seal on a foundation isn't necessarily permanent - things do fail over time, especially things subjected to water, pressure & freezing for more than 30 years. Additionally, asking about which sealant pushes this toward being a "shopping question" which is explicitly off-topic here.
    – FreeMan
    Commented Jan 12 at 14:16
  • I removed the "Please share your similar experiences --" because that just doesn't fit well here at Home Improvement. Please take the tour and a look through how to ask a good question to get a better idea of how things work a bit differently here.
    – FreeMan
    Commented Jan 12 at 17:31

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I'm not sure why a person wouldn't seal that joint. Every sprayed waterproofing job I've seen has overlapped the footing in that area deliberately and heavily. If that's what your situation calls for, do it. If the reasoning provided by these companies for not doing it makes more sense, don't do it.

Really, though, such sealing is a secondary measure. The primary mechanism for keeping water out is your drainage system. Ideally there won't be enough water coming under the foundation wall and up over the basement slab to cause a problem. If there is, something may not be draining properly.

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