Overcoming Water in the Basement (a bit wordy)

Discussion in 'Remodel Forum & Blog' started by Monte68, Jan 26, 2009.

  1. Monte68

    Monte68 New Member

    Messages:
    3
    Location:
    South eastern CT
    Hi all,
    Sorry about the length. Please bear with me.:rolleyes:

    My house is about 5 yrs old, and I want to finish a portion of the basement (about 2/3). My problem is that I have a high water table in the spring when the snow melts up north. I have a French drain and a sump pump. So far, this system has been very reliable. So long as the pump works, the basement will stay dry. But sooner or later, despite all my diligence, Murphy's Law says that if I finish the basement, that pump will fail one day. So I need to make sure I've done everything possible to avoid damage to the finished room.

    I know I can install a rubber backed subfloor, like a Dricore system, or I can build up the subfloor over 2x4s and a vapor barrier. My first question is this: If I should get a flood once in a great while (maybe once every 4 or 5 years) and if the water always stays below the vapor barrier, am I still likely to have problems, like mildew or other water damage, even if I remove all the standing water relatively quickly? Or will the basement floor beneath the room tend to dry up pretty quick because of the built in air passages below the sub floor?

    My second question maybe a little far fetched. I'm wondering, since I want to leave about 1/3 of the basement unfinished, if I can overpour a new layer of concrete on the existing floor, in the area that will be finished. Doing this would create a step where the finished room is situated on a floor about 2 inches higher than the floor where the sump is located. I'm aware that overpouring can create problems, but this would be a large (26'x30') indoor slab, trapped on 3 sides by the foundation walls. I don't see how it could go anywhere. Additionally, the original floor was never floated out, so it's rather rough. Don't know if that might help adhesion.

    Creating this step-up would buy me some time and some extra protection from flooding beneath the finished room. And if the floods I got when I first moved into the house are a good indication, the stepped up area might be above the highest water table mark, because I never got more than an inch or so of water anywhere in the basement. And it was always deepest near the sump. In the end though, I don't know if raising the floor with more concrete is just a waste of time and money. That's my question: Is this whole hair-brained scheme worth it, or should I just leave the floor alone and go with the vapor barrier. Or, with the threat of a flood always hanging over my head, should I just forget the whole thing?

    Sorry about rambling on for so long. :) Thanks for any advice you can give.

    Monte68
  2. frenchie

    frenchie Jack of all trades

    That is what I'd advise, yes.
  3. go for it....

    why not just put in a battery back up sump pump

    instead of trying to re-invent the wheel....




    I would personally just do the minimun on the floor, like some sort expensive epoxy paint throughout the whole area...

    then just use throw rugs...

    even if it were to flood you wont be crying too bad...

  4. Scuba_Dave

    Scuba_Dave Extreme DIY Homeowner

    Messages:
    885
    Location:
    South of Boston, MA
    Battery back up sump is a good idea
    I simply wouldn't use any material in the bottom few inches that would fall apart when wet, don't use wall board. Maybe use some cement board for the bottom 4" - that would be covered by trim. Use PVC trim

    If anything I would build the floor up on PT 2x in the finished area
    Have you priced concrete? :(
  5. cc777z

    cc777z New Member

    Messages:
    5
    wet basement

    I have a business doing residential carpet cleaning and water damage cleanup. From my research on flood damage control the following procedures will work in most situations.

    I'm currently redoing my basement due to a flood a couple years ago. My sump pump failed and ended up with 10 inches of water.

    As a result of this flood and some other leaky areas in the walls I decided to gut my basement. It is an old house and the basement is in good condition. Just has some cracks where water leaked in during heavy rains and during spring snow thaws.

    I'm sealing the cracks and then haveing one inch of spray foam applied. The spray foam is approved for stopping low levels of moisture. I will be sheetrocking with moisture and mold resistant sheetrock. It costs a little more but also more durable.

    At the bottom of the sheetrock I am leaving about 3 inches up from the floor. This will greatly add in drying any moisture from the walls. For baseboard I will be using a commercial style plastic base which is glued on. It can easily be removed in case of a flood. With the spray foam which is water proof and sprayed onto the studds the wood will get miminum water absorption and with the water resistant sheet rock will greatly reduce the amount of drying time when it does get wet.

    Short of many feet of water or sewage backup this should work well. Even with feet of water or sewage the spray foam can be cleaned off and the walls resheeetrocked. And with the foam sprayed on the sides of the studs they can be dried out in place and reused.

    As for your floor I'd leave it alone. Just don't put down any kind of permanent flooring. A loose carpet that can be pulled up or large area rugs will work just fine. There are also some types of cusioned flooring out there that can be laid down where the edges snap together. They can easily be pulled up in a wet situatation, dried, cleaned and reused. Check the flooring depts of your local home improvement stores.
  6. Monte68

    Monte68 New Member

    Messages:
    3
    Location:
    South eastern CT
    Thanks all for your comments. As suggested, I will be installing a backup pump. About building the floor up on PT, Can you use PT indoors? I was under the impression that PT offgases and shouldn't be used inside.

    cc777z, what is the foam called? Is it something I can apply myself, or is it only done professionally?
  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,332
    Location:
    New England
    Rather than building the floor up on pt lumber (which is notorious of twisting into a pretzel when it dries out), I'd consider some of the engineered panels designed for this that have a plastic bottom with domes on it to allow any moisture to migrate, if needed.
  8. frenchie

    frenchie Jack of all trades

    CC, are you applying foam, and then the studs? Or foam between the studs, with the studs touching the wall? If the latter, I see a problem: moisture in the masonry can't dry anywhere, other than through the studs. They'll rot.

    If you're running the studs inside the foam, then it's close to my favorite technique, although more expensive. I use rigid closed-cell foam board (the blue or pink stuff), tape the seams.

    A bit of moisture-transport-in-basements stuff for you:

    http://www.buildingscience.com/documents/digests/bsd-103-understanding-basements

    http://www.buildingscience.com/documents/reports/rr-0202-basement-insulation-systems

    http://www.buildingscience.com/documents/reports/rr-0509c-renovating-existing-basements

    But - again - I wouldn't finish a basement with flooding issues.
  9. Monte68

    Monte68 New Member

    Messages:
    3
    Location:
    South eastern CT
    Frenchie,
    Thanks for those links. What a wealth of information! I'm still left with a question though. Everything in those files addressed placing the insulation and the interior walls up against the foundation walls. I'm planning on having 3 of my 4 interior walls at least 3 feet off of the foundation walls. For the fourth wall, my plan was to leave a one or two inch gap between the interior and the foundation walls. In this case, isn't it adequate to leave the foundation walls alone (I'll probably paint them with Dry Lock anyway) and just insulate the interior walls between the studs like normal?

    Thanks
  10. cc777z

    cc777z New Member

    Messages:
    5
    Spray Foam

    As for the Spray foam I'm having a contractor that specializes in this doing the application. You can do a web search for Spray foam insulation. There are companies that do sell it to do it yourselfers. However, in my situation the cost was the same. So why do it myself. If I was applying several inches of spray foam doing it myself may be more cost effective.

    I'm using a 2X3 stud with a space for the foam to be sprayed on behind the stud. The stud won't be touching the cement wall.
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