Thread: Source of Efflorescence in garage

I found this efflorescence in the garage of a 5 year old brick veneer home. The spots were scattered along the garage floor near the wall closest to the laundry room. I could not find any moisture in the laundry room or inside the house and there was good drainage immediately away from the house but there was some ponding of water in the backyard roughly 12' from the house. My best guess is the water source is a laundry drain pipe leak in the slab. Anyone run across a similar situation and find a cause?

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Originally Posted by Sean Thornton

I found this efflorescence in the garage of a 5 year old brick veneer home. The spots were scattered along the garage floor near the wall closest to the laundry room. I could not find any moisture in the laundry room or inside the house and there was good drainage immediately away from the house but there was some ponding of water in the backyard roughly 12' from the house. My best guess is the water source is a laundry drain pipe leak in the slab. Anyone run across a similar situation and find a cause?

This will not be much help, but I think it is unlikely to be caused by a drain line under the garage slab. I have yet to see any type of plumbing go under the garage slab. It can be done, but I have not seen any.

Garage slabs are not required to have moisture barrier under it, so moisture could be coming from under the slab.
Could even be something was spilled or dripped on the garage floor.

Sean,
Water is coming through the slab. It may be just a small amount but I am confident that that is the cause. Drain line crack/break is a reasonable thought. Maybe in conjunction with a tear in a vapor barrier under the slab.

Rick,
Maybe a local oddity that you do not see plumbing under a slab. For for me it is a common occurrence. Though the garage is a little uncommon.

Originally Posted by Garry Sorrells

Rick,
Maybe a local oddity that you do not see plumbing under a slab. For for me it is a common occurrence. Though the garage is a little uncommon.

Which is it, common or uncommon?

Sorry Rick, Just a little uncommon but still see it on occasion.

Was on phone and typing at the same time, multitasking.

Could it be a low spots in the concrete?
Wet car pulls into the garage, water stands in those areas instead of draining away.
If it's only against the one side the vapor barrier could have came up a little short on one end, allowing the moisture to wick up.

Deicing salt can leave similar patterns.
Also what appear to be mouse feces in second photo?

Originally Posted by Raymond Wand

Deicing salt can leave similar patterns.
Also what appear to be mouse feces in second photo?

They look like dead ants to me. But I'm looking at a small screen.

De-icing salt would not be very likely in Brandon MS!

I'm going with Dog Pee! Yep, good ole dog urine will leave spots just like that on concrete. Urine as it evaporates becomes hygroscopic and attracts moisture (humidity) from the air.

The only problem with the dog pee theory is that they don't have a dog and the garage door has been closed.

Originally Posted by Sean Thornton

The only problem with the dog pee theory is that they don't have a dog and the garage door has been closed.

That is a problem! But you must admit the dog theory sounds good.

Originally Posted by Sean Thornton

The only problem with the dog pee theory is that they don't have a dog and the garage door has been closed.

How many times have I had a tenant tell me " I don't even have a dog!"?
Yeah, right.

I don 't remember ever seeing efflorescence on top of a horizontal surface, has anybody?

Originally Posted by Vern Heiler

I don 't remember ever seeing efflorescence on top of a horizontal surface, has anybody?

Yes, it is common here in cawlspaces that have a concrete skim coat over poly. Moisture defies gravity and comes up from below. That brings the white crystals out of the concrete.

The long narrow stain could be above a drain pipe. A bit of probing along the outer wall might detect a pipe. I recommend washing the floor. It's just a garage.

OK, if it has to be fixed, drill holes 2 feet apart in a grid pattern and inject a high tech liquid polymer to create a new vapor barrier.

Originally Posted by Rick Cantrell

How many times have I had a tenant tell me " I don't even have a dog!"?
Yeah, right.

Well may be they had a pig. It may be about how you worded your question.

Originally Posted by Vern Heiler

I don 't remember ever seeing efflorescence on top of a horizontal surface, has anybody?

Oh yes. Both basement and a few garages. Not often and in my experience it was high moisture under the slabs. Steel support columns in basement floors rusted though also. One builder's rep told they buyer that is was "normal" to have water in a basement.

This looks like absorption of some sort of liquid that is now efflorescing back out of the concrete---could be lots of things. Like Scott said, dog pee or cat pee is a good guess. Other things could be laundry detergents, solvents etc. Give it the old smell test

Originally Posted by Vern Heiler

I don 't remember ever seeing efflorescence on top of a horizontal surface, has anybody?

I have had it in my 1985 built home, in the garage floor. The soil is heavy clay and I live within 3/4 of a mile from Lake Ontario. The climate is very damp and efflorescence does appear. Just bringing in a rain damp or washed car will cause it.