To Waterproof or Not Before Finishing Basement

16 years ago

I live in Northern Virginia. My house is on a small hill with one basement wall (front wall) totally below grade, 2 side walls partially below grade,back wall totally above grade. The foundation is poured concrete. House was built in 1990. I have a sump pump and it appears to be operating properly.

When I removed existing builders insulation from walls, I found 2 vertical cracks in the foundation, one in the back wall and one in a side wall starting from the edge of a basement window. The side wall crack has oozed a small amount of water during recent heavy rains.

I am going to improve the grading around the house and put in some extended downspouts to get the water further away from the wall sides. In addition, I plan on sealing the cracks with poly injection foam.

I am debating whether to expend the effort to dampproof/waterproof the interior basement walls and floor since there appears to be a debate about effectiveness of such treatments. Other than the water periodically oozing through the crack in heavy rains, I don't have any wetspots on any of the foundation walls. Assuming that I can improve the drainage on the exterior, is it worth the effort to use a product like Dry Lok, RadonSeal or Sani-tred to waterproof the interior walls? If so, which product would be easiest to apply and most effective?

I also have both hairline and larger (1/16") settlement cracks in areas of the basement floor that have not let in any water (all are in the portion of the basement totally above grade)...should I seal the floor and those cracks also? If so, which product would be best?

At present my insulation plan for the basement is to glue XPS sheets on the concrete foundation, use metal studs to build the stud wall with fiber batts in between the studs. I am contemplating whether to use dry wall or Dens Armor Plus product to finish.

I'd really love to be able to use a product that allows you to remove the wall panels but haven't found one yet (would be nice if Owens Corning sold their basement finishing system to DIYers). If anyone knows of such a product, would love to hear about it.

Thanks.

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Comments (3)

worthy
16 years ago
Built in 1990, I expect there's nothing on the exterior but a bit of cutback asphalt. So I would definitely look to interior protection. I can't comment on the products you mention. My preference is a crystalline waterproofing product.

A minimum of 1" XPS adhered to the interior walls is a Building Science preference. I've used this method in the past, followed by fibreglass batts and a metal framed wall. EPS is also acceptable.

But I find the following problems with this method: 1) adhering the boards to the walls can be very labour intensive on a poured wall. The irregularities in the wall may make it impossible to use adhesive. In fact, I've ended up using concrete screws and fender washers. With the boards not fully pressed onto the wall, you will get circulating air on the interior wall, which can lead to condensation, as can, the screws and washers. 2) metal framing creates a straight wall and is less messy than wood to build, but if the boards are not sealed properly, they will attract condensation.

If you are using this method, it's best to use shiplap boards or seal all the joints with building tape. And be sure to put the baseplate of your metal framing on at least a 1" thick strip of XPS to prevent wicking of moisture into the wall through vapour movement or liquid water.

Most recently, I've had basement walls and rim joists sprayed with closed cell foam equivalent to Code Minimum R12, then wood-framed. The clients can then choose to insulate between the studs or leave it open.

You can also use crystalline waterproofing on the basement floor. Though with no water in 17 years, that may be overdoing it.
c2harvey
Original Author
16 years ago
I've read in a DIY framing book that you can experience "steel stud striping" when using steel-studs...essentially vertical stipes that appear on the covering drywall because the steel studs transfer heat/cold efficiently, making the drywall in contact with them cooler than the rest of the drywall and attracting dust that sticks to those cooler surface areas. Solution for that problem posed is to install rigid-foam insulation between the drywall and the metal stud.

Have you heard of this issue before? I assume if I can attach the XPS to my concrete foundation and seal all joints seems like this issue will go away...

You mention placing "1" thick strip of XPS under the metal base plate"...doesn't this XPS strip get crushed by the weight of the drywall once you hang it on the studs? Doesn't this result in a fair amount of tension on fasteners that attach the metal studs to the top plate as the XPS strip deforms?

Thanks for the input...
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Awhile back I sent this info to another poster but there was no response so I don't know if this product is available in the U.S. In any event the product is called XYPEX High and Dry and works through a crystallization process. I had used it in the basement of my last house , built in 1918, and it was wonderful ! I had a lot of cracks, some large, some small. The larger ones I cleaned out and patched with hydraulic cement, the smaller, hairline ones , I used the High and Dry , end of story ! End of leaks ! Their website is www.king-products.com Good luck.
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This is a really old thread, but for anyone that finds this (like me), let me share my recent experience. We had an unfinished basement for 10 years. Over those years, we had seepage through the walls due to improper drainage outside (this was a brand new house). I agree with the poster above that suggests you fix your landscaping. We had spots where water was pooling, and water just...finds a way. It's what it does. Anyway, also during that time, I worked down in the basement on top of some old carpet and pad that we tore out of a room we put hardwood floors in. Never had any issue with that just sitting on the floor. We recently had our third child, and decided it was time to finish the basement. We decided that we would waterproof the north side of the house that had most of the water seepage in the past. For the flooring, we put down linoleum in the bathroom, laminate in my office, and carpet in the main part of the basement where the kids would play. Lowe's sold us on the VERY BEST (their words) carpet pad for basements. It's this newfangled crap that has a "breathable" vapor barrier. So water can escape from underneath but not penetrate through it from above. That's the claim. Well, fast forward LESS THAN ONE YEAR... The whole area where that carpet is smells musty and gross. If you are going to use a pad, DO NOT, PLEASE, GOD, DO NOT buy anything with a vapor barrier on it, even if they swear it is breathable. It may be breathable, but not enough. The crappy 6 pound rebond stuff I had sitting down there for probably 7 years never did this. The moisture from your floor needs to be able to escape, not get trapped underneath there. Lowe's is now sending out somebody to look at it, and they will decide how to handle this problem. It is going to be a huge nightmare. Even if they are super cooperative, and offer to replace everything, I still have to move all of our stuff out of there, have it all tore up, clean up whatever mess is there properly (somehow I don't think Lowe's will do this part for me), and then get it reinstalled again. From other things I have read, if you are going to put anything over top of the concrete, you shouldn't try to seal it. Walls are one thing, especially if you have functioning drain tiles that will drain the water that has nowhere to go. I'd be interested to know if anyone has opinions on the laminate I put down in my office. Underneath that is the foil covered pad, which is...a vapor barrier.. Every video you watch on the internet says this is how it's done in basements. I get stopping the vapor from hitting the laminate, but worry now that it's just trapped and will try to creep up the walls. Home ownership is so much fun!
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worthy
16 years ago
No "striping" problem on my own home over three winters. I have been using XPS under the baseplates since 1998. Again, no problems. XPS is even used under airport runways and highways.

The XPS prevents transference of cold and vapour. Also, as it raises the base it keeps liquid water from such things as burst pipes, stopped drains, even ordinary cleaning from reaching the wood, metal or drywall,

Here is a link that might be useful: XPS Product Overview

To Waterproof or Not Before Finishing Basement

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c2harvey
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c2harvey
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