Thread: Water stained garage foundation

[Jerry I emailed this to you already but if you wish to respond on the forum that may help others. ]

There was not a leak or spill anywhere in this garage. This was a one year warranty inspection on a new home. The cracking was typical contraction cracking, but the water staining was odd to me. I have a few theories but i am not really sure what is going on. I thought the cool air from under the slab was meeting with the warm garage air causing condensation? Any thoughts?

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Is this an elevated slab or slab on grade? Just wondering how cool air is getting under the slab.
I'm betting this is a hold over from construction, either rain before being dried in or power washing, etc. and these are just low places.
There appears to have been at least two different events from the rings, whatever the cause.

There looks to be rolled up carpeting with staining on it to the side, what was it from?

Dog pee!

Exactly!

This is what I sent Jerome before I saw the post here.

You said garage, that looks like rolled up carpet to the right.

Garage floors are at (and sometimes below - although should not be below) exterior grade. However, whether or not the garage floor is below exterior grade, it is typically little higher (if any) than exterior grade.

Thus, sub-surface soil water (from rain, excessive sprinkler water, or just plain poor drainage) can, and will, migrate horizontally through the sides of the slab and between the slab and its moisture barrier. Once water is on top of the plastic sheeting, there is really only one place for it to go, up into the garage. This is caused both by normal drying out (moisture goes from wetter areas to drier areas) and by hydrostatic pressure (ground water pressing against the water under the garage floor, pushing it in further and up through less resistive (to water movement). Like hydrostatic pressure driving moisture through basement foundation walls - same cause and effect.

Is the rolled up (what looks to be anyway) carpet at the high side of the garage (near the step up ledge) or near the low side? If near the high side, then the moisture in the soil under the stepped up area under the main floor slab will have a greater hydrostatic pressure, driving the water down under and through the garage slab. If it is at the lower part of the slab, the same effect takes place - the lower it is, the greater the surrounding hydrostatic pressure against it is.

I doubt it is dog pee as it is only at those cracks. At least that's my take on it.

If it is moisture resulting from the crack in the slab, would we not see a stain along the entire crack?

The stains look like they were caused by something being poured on the area, not once but a couple of times. Really looks like urine from some critter.

Originally Posted by Scott Patterson

If it is moisture resulting from the crack in the slab, would we not see a stain along the entire crack?

No. I've seen many water stains located along cracks without water staining along the entire crack.

The stains look like they were caused by something being poured on the area, not once but a couple of times. Really looks like urine from some critter.

To me, those are too centered on the cracks to be randomly 'peed on from above'.

I still say it is coming up from below.

I'd agree with Jerry that the stains are from sub-slab moisture. They are way too symmetrical with regard to the crack to be from randomly deposited urine or any other liquid from above. How else would you explain the way they seem to radiate evenly out from the crack? I don't think Fido can (or would) aim for the crack, visible below carpet or not.
You wouldn't see a stain along the entire length of the crack if the moisture level isn't great enough to spread farther. It would only spread to the lowest points immediately adjacent to the holes where it exits.

Originally Posted by Jerome W. Young

[Jerry I emailed this to you already but if you wish to respond on the forum that may help others. ]

Any thoughts?

.

Originally Posted by Kevin Barre

... How else would you explain the way they seem to radiate evenly out from the crack? .................................................. .........................................It would only spread to the lowest points .

Or low spots in the pour that held moisture long after the other areas of the slab dried.

Yes at leastTwice.

I could consider the theory that the water evaporated and left the stains behind in the low spots ONLY if there was no carpet down at the time. If the carpet was down, it would soak up any liquid and really limit the spread. In that case, it wouldn't run over to a low point and stand there. It would seem to be too great a coincidence that the liquid spilled or was "deposited" directly over the crack twice.

Originally Posted by Jerome W. Young

[

There was not a leak or spill anywhere in this garage. This was a one year warranty inspection on a new home.

Originally Posted by Kevin Barre

I could consider the theory that the water evaporated and left the stains behind in the low spots ONLY if there was no carpet down at the time. If the carpet was down, it would soak up any liquid and really limit the spread. In that case, it wouldn't run over to a low point and stand there. It would seem to be too great a coincidence that the liquid spilled or was "deposited" directly over the crack twice.

Jerome,

Did you ask the Home Owner about the stain?

No dog or any other animal in the home. It is not urine.

Home owner claimed it just appeared in the last month after heavy rain.

There is another spot about 12 feet away with similar but smaller stains.

This spot is on the high side near the step up to the main house.

It is a carpet door mat that you see and yes it is stained.

" Up from the ground came a bubbling crude"

Originally Posted by Jerome W. Young

Home owner claimed it just appeared in the last month after heavy rain.

This spot is on the high side near the step up to the main house.

Originally Posted by David Banks

" Up from the ground came a bubbling crude"

Yeah After 11 months in the dry.

I just writes em, " Home Owner Stated bla,bla,bla,

Originally Posted by Kevin Barre

I could consider the theory that the water evaporated and left the stains behind in the low spots ONLY if there was no carpet down at the time. If the carpet was down, it would soak up any liquid and really limit the spread.

It did "limit the spread", didn't it?

Home owner report of appearance coinciding with a rain event really lends credence to Jerry's theory of water coming up from below.
Not from condensation from air under the slab, just rising water. Get rid of the high water and solve the problem, but that is going too far afield, just report what you saw, and maybe what was reported by the homeowner.

Originally Posted by Jerry Peck

It did "limit the spread", didn't it?

Jerry--
I'm not sure I get your point. By "limit the spread" I was referring to the theory that it was dog urine or other liquid coming from the top and then down thru the carpet, which then ran under the carpet until it hit a low spot along the crack where it sat. In other words, if it was deposited from above it would stay basically right where it hit (and was largely absorbed by) the carpet. It would not have a chance to seek out the low spots in the slab as some has surmised.

I couldn't (and still can't) see that as the cause; I felt all along that it was coming from below. That's what my first post said. I have a storage room in my crawlspace with a crack in the slab and I have seen water weep out of it after a multi-day rain. After it dries up it leaves a stain and slight efflorescence along the crack just like the photo appears to show.

Originally Posted by Kevin Barre

Jerry--
I'm not sure I get your point. By "limit the spread" I was referring to the theory that it was dog urine or other liquid coming from the top and then down thru the carpet, which then ran under the carpet until it hit a low spot along the crack where it sat.

Whoosh!

Went totally over my head. I missed that meaning. Sorry.