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I have a large unfinished basement. Concrete blocks walls. French drain. All but the top 18 inches or so are underground.

It's got great potential to be finished (9 foot ceilings).

The basement has a sump pump, which kicks on any time it rains. The concrete clearly sweats in certain areas. In one corner, there is a hole in the concrete at the very bottom about a dime size which trickles water after it rains. The water trickles down the french drain and finds its way out through the sump pump. In my 3 years at the house I haven't seen the water rise over the french drain, even during the heaviest downpours, but I admit it's a little disconcerting to hear water trickling into the basement whenever it rains.

Last summer I put Drylok on every inch of the concrete wall. 2 coats on the bottom half.

I'm thinking about getting some metal studs, framing out some walls, and making a kids room, family room, and bar area.

My questions are:

  • Do I need to put foam or some other sort of vapor barrier on the (already Drylok'ed) concrete walls before the studs go up? Or is the Drylok enough?

  • Is it OK that water will be trickling in behind the wall in that one area? I realize its wise to put a battery backup on the sump pump, plus I have a backup generator, but is there something that needs to done before finishing the basement, or can I live with the water getting in just as long as the sump pump gets it out?

  • Is it OK to use metal studs to frame it out? Seems like the way to go given the moisture, but also it just seems easier to manage than cutting so much wood.

  • If you were me how would you proceed to get the basement ready for finishing?

thedudeabides
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  • I would not finish a basement that is still this wet. Take care of the water issues first. After that, take a look at my answer here: http://diy.stackexchange.com/a/8644/1209 – DA01 Jun 18 '13 at 15:10
  • How big is the basement? Would building an insulated box well away from the walls provide enough space? – Chris Cudmore Jun 18 '13 at 18:09
  • Basement is about 50x30 ft. The water seeps into the french drain in one corner only. Maybe 5 or 6 feet of wall space where you would see water seeping into the drain at times. (We plugged the original dime-sized hole but obviously the water still seeps through in that general area.) It would be fine to leave that area unfinished. Is there any issue relying on the sump pump to prevent the water from rising into the basement, provided we're planning for backup battery and generator? How much space is "enough space" away from the walls, and does that apply only to the area where water seeps? – thedudeabides Jun 18 '13 at 18:55
  • There is nothing wrong with relying on the sump pump. You need to account for two factors - #1 You could have a minor flood - so plan your flooring accordingly. #2 You will have high levels of moisture. You sump pump will not pump out everything. Some moisture will make its way to your basement climate, increasing the chance for mold growth in things like common drywall. – DMoore Jun 19 '13 at 05:44
  • Drylock is neither an insulator nor waterproofer. It's merely a moisture barrier. – DA01 Aug 29 '14 at 15:43

3 Answers3

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The right way to do it is to have the outside entrenched and have any cracks patched with hydraulic concrete, drylock and delta board, as well as having new weeping tile put in below the footings. Unfortunately, this will cost you about $100 - $150 a linear foot.

Then I'd go with closed cell spray foam on the inside. Metal studs are fine in this case, as you're going to stud out an inch or two away from the wall so they can spray in behind. (Note: wiring and plumbing go in before the foam.)

Like I said, this is a very expensive process, but it will be done right, and it will last for a very long time.

Chris Cudmore
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  • You're saying you wouldn't recommend to move forward without addressing the water? I thought the french drain system is designed to allow some water to enter (and exit, more importantly) in a controlled fashion. Is it not advisable to finish a basement with a french drain that takes in occasional water to the sump? – thedudeabides Jun 18 '13 at 17:20
  • I'm not saying it won't work. I'm just saying it's sub-optimal. I'd be worried about what's going on behind the walls. – Chris Cudmore Jun 18 '13 at 18:50
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In addition to Chris Cudmore's good advice, you could use rigid foam sheets such as Styrofoam or Super Tuff-R. The latter has a higher R value (2 inches is R-13).

It could bemounted continuously behind the studs (better for establishing a thermal break and avoiding air leaks) or in between the studs of you are short on space.

The boards should be sealed with the proper tape, again to block air leaks. Leaving an air gap between the board and the wall slightly increases the R value.

bib
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They make both wall systems and flooring systems for wet basements. Sorry I am not posting links but don't feel like shopping today. A friend just put up wet basement panels (google that) and they look good and they are waterproof.

Whether this is the right solution for you depends on your house and how long you expect to be there. If your yard is graded poorly, your basement walls are in really bad shape, or there is some other intrinsic issue that will always cause moisture I would personally not do what Chris or bib suggested.

First it is a basement. How much are you willing to spend to make a place that naturally has water nice - there are "newer houses" and houses built in dry areas that don't have issues which are perfect to renovate - but that is not your house. I have seen many disappointed people spend thousands of dollars waterproofing basements to have their (newly finished) basement spring a leak the next year.

My suggestion is make the basement livable, safe, and enjoyable. Knowing that it could get flooded at some point. I would suggest putting in water-proof (rubber) planked flooring - HD sells this. Even if it is soaked it can be cleaned and reused. I would suggest some waterproof panels set about 4-6 inches from exterior walls. I would suggest no insulation other than rigid foam paneling. And if you do the foam paneling I would allow space for it to breathe. I would suggest neither drop ceiling or drywall for the ceiling - just paint it black or white (white you have to clean more).

If this extra space is really important to you - and you want it nice - I would suggest that you look at adding an addition to your house. After you do all of that waterproofing, foundation repairs, and finish your basement your $$$ is getting pretty close to adding on plus you don't have to worry about it being flooded.

DMoore
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  • Yeah, my solution is expensive, and other options for the space should be explored. – Chris Cudmore Jun 18 '13 at 18:04
  • Your advice is right though. It would be something that someone would do living in a high $ metro area where adding on isn't an option. – DMoore Jun 18 '13 at 18:08