Hey folks! I'm currently working around my foundation because I've noticed a small puddle forming in one corner of the basement during heavy rain. I have a couple of questions that I need advice on:
1. I'm thinking about installing a foundation wrap (like Delta-MS) to create an air gap between the wall and the soil. However, I'm concerned about the long-term effects. Could this air gap potentially lead to problems, like trapping moisture and causing damage to the wall over time?
2. I have a two-slab footing setup (here's a [picture](https://imgur.com/a/EeJhVby)). Typically, water only gets to the lower slab, but during heavy rains, the upper slab gets affected too. The foundation wrap will cover the lower slab, and I plan to install a French drain there. Is that sufficient, or could leaving the upper slab without drainage cause issues later on?
Thanks in advance for your insights! I want to avoid having to redo any work if I can prevent it.
2 Answers
This situation looks a bit concerning based on your picture. It appears that the lower slab may have been installed after excavating below the foundation footing, which could explain why water accumulates there - it's possibly moving under the footing due to rising water levels.
If you install a perimeter drain under the slab, be cautious that it doesn't compromise the footing's stability. Also, a dimple board is effective, but it doesn’t fold at corners, which could create bulk that’s tricky to manage.
1) No worries! Using a dimpled mat or similar drainage membrane will actually help keep everything dry and prevent any water intrusion issues.
2) Regarding the water reaching the upper slab, it sounds like it’s due to rising water levels. Installing drainage on the lower slab should typically handle that, but you could layer your drainage wrap for added security. For a budget-friendly option, consider using foundation sealant covered with plastic, but remember you'd still need a drainage system to keep the water away from the house.
1. That's great to hear!
2. Exactly! There's another spot about 3 feet away where I get a fountain effect from the slab itself due to hydrostatic pressure. I'm planning to break the cement and add a pipe leading to the sump pump. But about the sealant, wouldn’t that just trap water inside the walls? I thought it was just a short-term patch and not a long-term solution.
Yes, it seems they excavated the crawl space below the footing, which is why it had to be extended. I'm thinking about putting in an interior French drain with plastic on that side, while the rest of the perimeter seems fine. The plan is to dig a small trench, lay a perforated pipe, cover it with plastic, and then cement over it.