Finishing 100 yr old basement with minor hydrostatic water issues

nadjahoggFebruary 12, 2012


This is my first post here- My husband and I own a 100-year-old home in St. Paul,MN (lived here 5 years). Our basement was cosmetically finished around 1970 (walls, ceiling, but NOT the floor). We'd like to make it an even better living space and update it, and finish the floor, but we are concerned about how to properly deal with potential water issues.

We have witnessed some minor, seasonal water seepage from the floor and we think the problem is mainly hydrostatic pressure. Some years there hasn't been any water at all.

The foundation walls are 19-inch thick limestone, which is in really good shape. The floor is about 2 inches of 70-year old concrete. We do have adequate headspace and an egress window already.

Here is what we have considered:

1) Installing drain tile

2) Sealing the floor and/or walls with a product like Sanitread (though we're worried that sealing a limestone foundation won't be good in the long run).

3) Repouring the floor, reinforcing it and making it thicker, and with modern cement additives that will help make it resist water and give it resistance to hydrostatic pressure

4) Not finishing the floor, so water can seep , and dry out if needed (the least interesting option to us)

5) A mongo dehumidifier (*we already use a small one*)

We have already landscaped properly around the house, and we have long gutters, etc

We would like to solve this problem from the inside- Digging on the exterior is out of the question cost-wise.

Can any of you recommend what options (or combinations of options) might be best- and things we haven't thought of?

Also- if you have any suggestions on how to heat the space efficiently (it's currently got 1970's era electric baseboard heat)....

We're pretty handy and have done a lot of work on the house so far- we're not scared of work (like taking out the floor and re-pouring it). We just want to make the right choices and only have to do this once. We know mold is a terrible problem to have, and that's the last thing we want.


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Assuming the limestone walls are still in good condition, you can insulate them and provide interior drainage. But 2" of concrete probably over native soil isn't doing much to keep dampness and liquid water out. If you dig down though, you have to be careful no to go below the level of the existing footings or bottom course of the limestone if there are no footings.

See this thread from "Derek" down. Note especially the link to Building Science Corp.

Instead of trying to make concrete waterproof, you want to provide drainage under the slab to the perimeter drain.

For heat, why not use the existing furnace? Perhaps supplemented by a decorative gas stove or fireplace.

    Bookmark   February 12, 2012 at 3:12PM
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Regardless of what you end up doing, you should seal the limestone with a silicate sealer. It will react with the high lime content and help densify, neutralize, and strengthen it. Look for a sealer with high silicate content. it will still allow the limestone to breath, but greatly reduce the vapor permeability.

The floor is a little bit tricky because there are only a couple inches of concrete. I think silicate is not an option because it penetrates too deep and will go right through it. Look at a sealer called claims to resist hydrostatic pressure

    Bookmark   March 29, 2012 at 11:22AM
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Some experts consider silicate and other sealers likely ineffective where there is continuous water and pressure.

    Bookmark   April 7, 2012 at 11:31AM
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It's fascinating how most of the miracle "waterproofing" cures never back up their incredible claims with independent lab tests. "Hey, if it costs $299.99 a bucket its gotta be good! Everybody knows you can't say something on the internet if it's not true."

    Bookmark   April 7, 2012 at 11:38AM
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"Hey, if it costs $299.99 a bucket its gotta be good! Everybody knows you can't say something on the internet if it's not true."

It used to be in print adds, and even on TV.

Nothing really seems to change all that much.

"Those who cannot remember the past are condemned to repeat it."
George Santayana, Life of Reason, Reason in Common Sense, Scribner's, 1905, page 284

    Bookmark   April 16, 2012 at 3:25PM
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nadjahogg: wondering how you make out with your basement project? We have a similar issue in our 1950 Cape that we've been trying to determine how to tackle. The basement was finished in the 80's but a couple times some of the very severe storms (with record rainfall) have produced some hydrostatic leaking through the concrete floor. We have a sump pit in one corner of the basement but in severe rain situations water will still push through cracks in the concrete floor.

The last time it leaked, I gutted the finished basement and have been debating what to do to correct the issue and finish the space off again. The house is small, so losing that extra living space has made it feel even tighter.

Here are a few of the things we've considered:

1. Exterior Drain Tiles (would require significant excavation work)
2. Interior French Drains
3. Additional Sump Pit
4. Rubber Interlocking Floor Tiles - Easy to remove and clean up water if it leaks down the road

The contractors I've talked to seem to think that options 1-3 are simply not worth the high cost; just to get the basement to a point where it could be finished off again.

Was curious what you decided on and if you had success with your project? Thanks!

    Bookmark   July 2, 2012 at 9:51AM
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