Unexplainable damp areas in carpet

May 21, 2007 10:51 PM

Two chronic, unexplainable (to me) damp areas in the household carpet. Help me find the culprit, please.

Description:

One is ~ 3' by 1 1/2' located where living room carpet meets kitchen tile.

One is ~3' by 1' located by rear bedroom door (nowhere near a water source).
Neither is ever saturated with water. Just enough to make the carpet a little darker (its a light color carpet)
No indications of dampness on walls or ceilings

Possible causes I Have investigated:
Leaks from roof
pet stains
faulty/leaking kitchen equipment
faulty/leaking ac unit
faulty attic insulation causing moisture to drip

'm afraid this could indicate a problem with the foundation. Just don't want to go tearing out my floor to find out that it could be something simple I overlooked.

Mefites, please help!

posted by donmayo to home & garden (13 comments total)

The fact that "pet stains" is on the list of potentials screams out for my attention.

Assuming you have a dog or a cat, a sudden tendency to start urinating in the house (dog)/out of the catbox (cat) can have many causes, from not leaving sufficient light on at night for the dog to find their way to the doggie door, to a urinary tract infection, to diabetes, to good old fashioned old age, to...well, sometimes pets just do things for no good reason.

Next time you stumble across the moisture, drop some folded paper towel on it, apply pressure, and see if what comes up is yellowish -- that's a pretty good urine indicator. And remember, with dogs at least, once they've peed in a spot or two, they'll keep doing it in the same places. Recently my dog peed several times in one spot on a carpet, and so we ditched the carpet. A few days later, he peed on the same spot where the carpet had been, just out of habit (we'd cleaned the spot, so it wasn't the odor.)

As for you suggesting it might be a problem with the foundation -- is this a basement? If not, I can't imagine how the foundation could be involved.

Finally: does it ever dry out? Or is it always a little damp?
posted by davejay at 11:13 PM on May 21, 2007

I think everything's probably OK; the dampness is most likely to be condensation from moisture in the air.

Both the kitchen and the bedroom have a lot of moisture in their air (cooking and breathing) and when this air hits a cold surface the water will condense on that surface.

You can cure it by reducing the moisture in the air (did you get a humidifier as someone suggested in the static electricity thread?) or by making the floor warmer, possibly by putting in carpet padding with a higher R-value, but if you do that, the water will probably just go somewhere else in your house.
posted by jamjam at 11:28 PM on May 21, 2007

Ruled out pet stains a while back.
Not a basement.
The reason I mention foundation is I think maybe cracks that moisture pool into.
Never dries out. Always a little damp.
posted by donmayo at 11:32 PM on May 21, 2007

Probably not air moisture. I live in South Louisiana (think Florida Everglades, only more sweat, in summertime). These spots have been around even in the cool (non-humid) seasons.

Not dismissing the idea. Just want to provide neccessary info.
Thx for the suggestions so far.
posted by donmayo at 11:43 PM on May 21, 2007

I think you can pretty easily rule out pet and ceiling problems. Just put something like a stool or chair at those two areas. The pets won't pee on top of it, and if it's coming from the ceiling, you'll soon get water on the seat.

My 1st guess it that's its a ground level problem. Is there any way you can lift the carpet up for a while?
posted by Cog at 12:16 AM on May 22, 2007

If it was pet urine, you'd be able to smell it. (Ammonia...)
posted by Steven C. Den Beste at 12:38 AM on May 22, 2007

Is this floor on a slab?
posted by Opposite George at 12:56 AM on May 22, 2007

Like cog said rule out it coming from above by placing something on top of it. If it's coming from below then you could have a crack in the floor and moisture under the slab that is wicking up through the cracks. Does it get worse after it rains?

If you do have a crack you'll need to rip up that carpet, wouldn't want mold to start growing under your carpet.
posted by zeoslap at 6:23 AM on May 22, 2007

I just had a similar problem at my house in northern Florida. House built in 1992, wood frame on concrete slab. Copper pipes under concrete slab plumbing. A hot water pipe to the kitchen started leaking, under the slab. Within a week or so, the "damp spot" progressed to a puddle 4 by 6 feet that a wet vac couldn't really keep up with. The temporary fix was to rip up the carpet, knock a hole in the concrete slab, repair the leaking pipe, fill in the hole with quickcrete cement, and restretch the carpet once it and the pad had dried. The permanent fix will be to re-plumb the house in PVC through the attic, which will cost about $4000, and which I'll do next month.

This area has hundreds if not thousands of homes of this era, built with this type of plumbing, and according to the plumbers I called in, dozens of them every month are now coming up with this problem. They had a complete set up for dealing with this, including an electric jackhammer for knocking through the slab. Once on the job, they were in and out in about 4 hours, as a two man team, at a cost of $550. The water pressure is a little better now, and perhaps I will save a bit on water and electricity, now that I'm not losing hot water. I don't like to think what hundreds of gallons of hot water washing through the soil under my slab have done to my termite pre-treatment, but I'm going to have my exterminator come out and side spike the slab to renew my termite protection, too.
posted by paulsc at 6:43 AM on May 22, 2007

Probably not air moisture. I live in South Louisiana (think Florida Everglades, only more sweat, in summertime). These spots have been around even in the cool (non-humid) seasons.

Even so, have you taken any humidity readings from within the house? Do you have a basement? Try taking some digital shots and upload them to a free image host like photobucket.com.

If the floor is on the foundation's slab, it is possible that the cinder-blocks (hollowed out concrete) are retaining pools of water and slowly leaking out/refilling during rain. The first way to combat that is to go outside during the next storm and watch how your roof drains handle water, making sure that as little water as possible runs down your outer walls or washes back towards your foundation.

If it is air humidity within your house (not outside of course) then it could simply a matter of condensation...the same effect you get on the outside of a mlik jug when it is left outside the fridge. The carpet spots might be in areas where there is a noticiable change in temperature where condensation could occur.
posted by samsara at 9:22 AM on May 22, 2007

Oh almost forgot...I wouldn't rule out a plumbing issue either. Even it is across the room, water has a tendancy (due to surface tension) to travel along beams or pipes. Without pulling up the carpet, you might want to try turning off the main water valve to see if the spots evaporate after a few days (tough thing to do tho).
posted by samsara at 9:25 AM on May 22, 2007

We had a similar problem, but it turned out to be a problem with the sump pump. The pump wasn't working correctly, and the water was filling up pipes under the foundation. (At least, I think that's right.) If you had a sump, you probably would have mentioned it by now, but it's a thought.

We also had a problem in our kitchen where water was getting in under the siding near the sliding door, and somehow running between the floor and what's under it (the ceiling of the basement, basically). The water wasn't really near the entry point -- it was pooling somewhere else. So you might want to double check for outside sources of water (but, think you'd be able to smell mold/wet/whatever by the time it actually seeped into the carpet).
posted by dpx.mfx at 9:29 AM on May 22, 2007

What happened to paulsc also happened in my rental. It might not even be a pipe that leaks, but if the slab has a crack and there's no seal over the ground, and your house is on top of ground that's often wet, water will wick up around the crack, and as mentioned, it will be far worse in wet weather.
posted by slow graffiti at 1:15 PM on May 22, 2007