Installing a sub-floor for eventual carpeting

Old 02-15-16, 12:59 PM
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Installing a sub-floor for eventual carpeting

My new/old home was once a commercial building. Built on a concrete slab and probably many feet thick, too.

Two of the rooms I will make into my bedroom and living area and they have the worst floors. One has a four sided slope to an old drain and the other badly pitted from leaving wet carpeting there to rot the top layer. Not a pretty site and was hidden from view by the seller with carpets and furniture. Water under the bridge, now.

What to do. I feel the best way to move forward is to find the highest point and level the floor to that and create a sub-floor of 2x3's and plywood. Once completed I can have an installer lay wall to wall and make it a nice, cozy area for me and my little dog to live in.

The sub-floor I can do myself, with some help, but I need some advice.

1) should I think about coating the old floor with something to keep it dry... either a floor paint or some kind of a sealer product?

2) running the studs around the base of the wall... better to cut away the existing sheet rock or just attach over that?

3) should I install plastic as a moisture barrier atop the studs before I lay down the plywood?

4) any issues with using insulation between the studs to try and keep the heat in and would I want to use foam boards cut to fit or rolled fiberglass?

Any other advice or other suggestions will be greatly appreciated.
Old 02-15-16, 04:21 PM
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1) What is causing the floor to become wet? Is there a plumbing leak or back up in that drain you mentioned. Just coating the floor won't keep it dry. The coating will peel off with water from underneath causing it to come loose.
2) Studs are vertical members. I am sure you mean "joists". You will need to determine a level line across the entire floor area so your joists can either be shimmed up to level, or trimmed down to make it level.
3) Any moisture barrier should be applied before the joist framing is put in place and no nails through it. Your joists should be attached to each other or the framework you create.
4) Insulation would be optional, but a product like Roxul or foam boards would be optimal.

Just so we can help you better, post some pictures of the place. That way we can see what you see.
Old 02-15-16, 04:31 PM
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I'm thinking in terms of self leveling compound although, a floor the size of what you are talking would probably be best served by a professional as the pour is large and doing by the bag will be tricky. You can also look to something like gypkrete although, I am not sure the minimum thickness as it is brittle.

Also, if just doing wall to wall carpet, it will hide a multitude of sins under a nice 8lb pad and some good quality carpeting. Save yourself the hastle. Cap off the floor drain, level that general area and then carpet. My concerns are trying to create a wood subfloor out of inferior materials touching concrete (a no no) and hoping you don't end up with a bouncy mess when you are finished. You also will reek havoc on the height of the door openings and other specific items in the room.
Old 02-16-16, 01:13 PM
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Per your request I have provided a pic to try and let you see what the deal is.

The floor area (back most room in picture) that appears to have been damaged by allowing water to sit in contact with it for some period of time is in the room that has no drain. There are two seams in the concrete in that same room and one of them, if I leave carpet over it, seems to pull water up. At least it did the first time I tried it.

Perhaps sealing that seam with concrete cement will prevent this from happening but it is also why I think installing the sub floor above it is the way to go.

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As you can see the floor is not really level at any point. Goes off in all directions.

The door in the picture goes outside to the carport. I would only seal/paint that area in front of the door and to the right where it goes downstairs three steps to a bathroom and wash room. So coming in you would need to step up (say 3 to 4") to get to the new sub floor.

Alternative is to cut the bottom of the door and let it meet the new height. I still want to tile or do something there for when you are coming in with wet shoes or boots in the winter. Go down to the bathroom/mudroom and change shoes, hang coat, etc.

Not seen in the picture but behind where the camera is there is another door that goes to the rest of the home. It already has a sub floor with wood flooring. You need to step up a good 5". So anything I do here will only meet up with what was done prior.

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