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Prepping a basement foundation for finished basement down the road

Mike Tew | Posted in General Questions on

We are looking to finish the basement of our 100yr old house in a few years. I know there are some potential moisture issues with the rubble foundation. We usually experience some flaking during the spring thaw. My thoughts on repairing the foundation is to have the interior and exterior reparged / repaired before we even consider any waterproofing.

One that is done, should we give it a year before we invest in waterproofing or can we do that after its hardened (after 28 days)?

Also, given the potential issues with digging up the exterior foundation and re-disturbing the soil, it seems best to go with an interior solution. We don’t have any major water issues (ie. flowing) with the interior, but there is definitely moisture present given the nature of the rubble / cement mix. Before we stud I’ve heard everything from running tyvek (building paper) to weeping tile on the interior. One problem mentioned by a local contractor with tyvek (unlike an weeping tile) is the potential thawing of frost on it in the spring, and that the water won’t have anywhere to go. Obviously there is a huge price point difference with doing an interior weeping tile, but is it a must?

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Replies

  1. GBA Editor
    Martin Holladay | | #1

    Mike,
    These decisions involve judgment. If you want to do all the work from the interior, the best (most thorough) job would involve an interior French drain at the perimeter of your slab, with the perforated pipe leading to a sump equipped with a sump pump. You would install dimpled membrane on the walls, with the bottom of the dimpled membrane installed to conduct water to the French drain.

    Then you would install your studs,with at least a two inch gap between the back of the studs and the dimpled membrane. And then you would install closed-cell spray foam against the dimpled membrane.

    Whether or not you can get away without the French drain and the dimpled membrane is a judgment call.

    Here is a link to an article with more information: Fixing a Wet Basement.

  2. Mike Tew | | #2

    Thanks Martin. The link was very helpful.
    It's defiantly not an easy decision. I still think interior is the way to avoid any cracking or breaking from an exterior dig.

    I've already had a few contractors come and quote. Omni basement does offer an lifetime guarantee using interior system with flush out hatches in case any blockage occurs. The one thing that does strike me odd is that they use that bubble wrap on the wall vs. and dimple board. Thoughts?
    They have a video here of the product https://www.youtube.com/watch?v=hQ5m-zXkpbU

  3. Charlie Sullivan | | #3

    It's not clear exactly what their system is, but the use of metalized bubble wrap is likely to be a red flag--it's generally hyped as offering advantages that are not real, and might indicate a dishonest or clueless contractor. See
    https://www.greenbuildingadvisor.com/blogs/dept/musings/stay-away-foil-faced-bubble-wrap

    I'm also a little suspicious of a company that doesn't provide a clear description of what their system is, especially if the only place you get clues about it is a youtube video.

  4. Mike Tew | | #4

    Hi Charlie,
    Yes, it does smell a bit too good to be true. I have read that link before. This page on their website is more clear http://www.omnibasementsystems.com/basement-waterproofing/french-drain.html.

    Again thought, they don't really explain anything about the wall other than their drain design.

    It beginning to feel like the best option is to have the driveway redone / re-graded (currently gravel) and give it a year. Our eaves just got done this week which will already improve things.

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