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Delea 08-19-2013 12:36 PM

Wet Concrete Under Carpet
Hi There,

I'd like to start off by saying that I know NOTHING about renovations/home building etc. I'm trying to branch out to some more knowledgeable folk who may know what needs to be done and then I will very likely contract that help out.

I just bought my first home. It's a late 1960's home, new wiring, plumbing etc. and main floor completely renovated. The basement looks like it was renovated within the last 15-20 years, but done as cheaply as possible. It has some very flimsy, cheap looking faux wood panelling and then the worst carpet you've ever seen.

We rolled up the existing carpet and underlay as we intended to get new carpet installed this week. Unfortunuately we found water and dirt under the carpet. The dirt was mostly in one corner, but there are some spots where you can see cracks and dirt has run along the floors. There are parts where the paint thats on top of the concrete has bubbled up and when you disturb it, the paint layer comes off and what is underneath is concrete but not hard, smooth concrete, its more chunky and loose (is this normal? I imagined homes had concrete subfloors that looked more like sidewalks, smooth and solid, not this loose concrete look). We've started to remove the wood panelling and insulation to see where the water is coming from in the corner so we can hopefully seal it. But what do these patches on the floor mean? And what about the loose concrete? As I said before - is this normal? This issue seems to be contained to only one portion of the basement, thank goodness. This is the only room where carpet was laid, so the rest of the basement is bare concrete and we can see that there is no moisture or cracking.

Any help would be MUCH appreciated.

Drywallinfo 08-19-2013 04:58 PM

Sounds like water has pushed up through the floor since you say you are seeing dirt. It might be hard to seal this up but do your best by removing loose concrete, patching and painting with the best basement water sealing paint you can find. The one for-sure way is to keep the water away from your foundation. Landscaping and gutters alone can help a lot. Otherwise, a sump pump and better yet a sump pump with drain tile.

Otherwise, you can get moisture under a carpet like this from humid air condensing on the cold floor. Is the basement open to the outside air? Is it musty smelling? If so, sealing off the basement and running a dehumidifier would correct this. This is something you will want to do regardless.

The loose concrete almost sounds like they may have poured a thin layer over the top of the existing floor at some point.

nealtw 08-19-2013 06:26 PM

Both the drain tile and foundation waterproofing on the outside are well past their lifetime. There are other solutions but if at all possible upgrading the outside is the best and will last the longest.

WindowsonWashington 08-20-2013 05:53 AM

+1 to Neals observations.

You are going to need to start budgeting for some repairs of some significance depending on how you approach this project.

Jungle 08-20-2013 10:49 AM

If you just bought the house, you might want to talk to a lawyer, unless it was 'as is.'
If you paid for a working basement; the whole basement might need to be gutted, once you get water coming in there.

Drywallinfo 08-20-2013 12:17 PM

I would recommend a sub-floor product under your new carpet like dricore (see ) We get moisture in our basement once in a while but this keeps the carpet in my basement office high and dry (and warm). In my small office area I did not even bother fastening the product down - I just left it float. But first, you should do all you can to eliminate the moisture.

Delea 08-22-2013 12:12 PM

Thanks for all the advice everyone.

Our game plan as of now is to fill any cracks and reseal the concrete floor. And then repair the outside soon, but not right away as we need to save up the cash to budget for that!

Should we also take down the existing wall panelling and insulation and re-seal that concrete as well, or should we just start with the floor?


nealtw 08-22-2013 06:59 PM

You have had water so itis time to do some inspections on the construction of those walls with paneling on them. You could have some mold there at the bottom of the walls. This should be addressed before you create living space down there.
As your basement was finished some time ago. I will run thru what it should look like so you can judge how well it was done.
Never add new material to the basement before all water problems are solved and it is dry.
The walls against the foundation should be a regular 2x4 or better wall no closer to the concrete than one inch. With studs at 16" or 24" on center.
The bottom plate of the wall should have something between the wood and concrete like tar paper, poly or sill gasget (foamy plastic sheeting)
If these walls extend floor to ceiling the space behind that wall should not be common to the space between the floor joists, This is a fire stop to give more time for people upstair to get out when a fire occures..Insulation (batt type should never touch the concrete and the wall should have vapour barrier on the warm side in cooler zones.
After a flood wood needs to be inspected for mold growth and rot of any kind. Walls with drywall should have the drywall removed to just above the flood level and allowed to dry before repairs are done. Walls that have not been allowed to dry properly is a great source for problems.

alesha 08-24-2013 09:40 PM

We bought a home as is and had water as well. are there any windows with obvious leaks? We had glass block and concrete to seal off water coming in and then fixed the gutters. Not to scare you but mold loves water so you may want to check out behind the walls. We had to do a full gut down to the studs.

Drywallinfo 08-25-2013 08:28 AM


Originally Posted by Delea (Post 90724)
Thanks for all the advice everyone.
Should we also take down the existing wall panelling and insulation and re-seal that concrete as well, or should we just start with the floor?

I think maybe just take enough paneling down to inspect for mold and water damage in the insulation in different locations. Then go from there.

The humidity issue is something to consider too. Just this morning I noticed dampness on our basement floor. I had a dehumidifier running and even ran AC yesterday but forgot about one very small window left open - that small opening was enough to let in all kinds of moisture in from the hot humid air outside.

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