View Full Version : Moisture mystery

Frank Bombardiere
06-12-2007, 03:58 PM
I just inspected a 1985 floating slab foundation home with a detached garage. The garage has moisture stains all the way around the stem wall on the interior. The walls along the baseboards is pegging my meter. The stem wall is about 4 to 6 inches above grade and the drainage was not bad. I am thinking maybe a vapor barrier problem but have not seen this before. I do not even know what to recommend in regard to a specialist to find out what is going on. I suspect the walls will need to be opened to see what is in there. Any suggestions would be appreciated. The roof is not leaking either,

Scott Patterson
06-12-2007, 04:14 PM
By chance did you check the water meter to see if they might have a leak under the slab or in a wall? Would not be unheard of for this to happen.

It could be a moisture barrier, but unless that ground is really wet I would not think that moisture would wick up in the walls that far.

Jerry Peck
06-12-2007, 04:14 PM
From the IRC. (bold is mine)

- R506.2.3 Vapor retarder. A 6 mil (0.006 inch; 152 μm) polyethylene or approved vapor retarder with joints lapped not less than 6 inches (152 mm) shall be placed between the concrete floor slab and the base course or the prepared subgrade where no base course exists.

- - Exception: The vapor retarder may be omitted:
- - - 1. From garages, utility buildings and other unheated accessory structures.
- - - 2. From driveways, walks, patios and other flatwork not likely to be enclosed and heated at a later date.
- - - 3. Where approved by the building official, based on local site conditions.

Could be that there is *no* moisture barrier, and that it is *not* a "problem" (not technically anyway).

"The stem wall is about 4 to 6 inches above grade and the drainage was not bad."

There also may not be any dampproofing/waterproofing on that stem wall as it may also not be required? I say 'may' because R406.2 does not specifically require dampproofing/waterproofing of foundation walls for garages.
From the IRC. (bold is mine)

- R406.2 Concrete and masonry foundation waterproofing. In areas where a high water table or other severe soil-water conditions are known to exist, exterior foundation walls that retain earth and enclose interior spaces and floors below grade shall be waterproofed from the top of the footing to the finished grade. Walls shall be waterproofed in accordance with one of the following:
(then it lists waterproofing methods)

The garage is not really a "floor below grade".

Frank Bombardiere
06-12-2007, 05:27 PM
There was a garage next door within 15 ft of this one and it did not have these issues. There was a sprinkler system around the garage, but not on the rear wall and it was the same as the other walls. And yes I did check the meter and there was not leakage indicated. I have attached a pic of the staining. Who should I recommend to repair or figure out for sure what is going on here?

David Banks
06-12-2007, 06:56 PM
Owner washing his car inside garage?

Jerry Peck
06-12-2007, 07:13 PM
See, what is strange to me is that the curb around the garage is water stained, the owners placed dry things on a pallet to keep them high and dry, and that other thing (wood or metal) shows water stains along its bottom, yet there is very little water staining of the wall materials themselves.

If water was leaking in and down the walls, the walls would be stained.

Or so it seems to me anyway.

Frank Bombardiere
06-12-2007, 08:53 PM
That was Cedar panels in a closet at the rear of the garage and the walls were wet down low. Of course they have had termite issues and the home has been treated. The cedar panels were wet as well. The house was vacant, so I doubt there was any car washing going on. I am leaning towards constantly moist ground due to sprinklers and no water proffing of the foundation causing wicking. I guess I will just suggest a general contractor to try to get to the bottom of it or try myself for additional fees. If it is as I suspect, I really don't have any solid answers other than water proofing as much as possible and having the sprinkler system serviced to assure it is not spraying the walls and no leakage.

David R2
06-12-2007, 09:05 PM
is water leaking from suppy pipes in the slab?


Frank Bombardiere
06-12-2007, 09:35 PM
There were no supply lines and it is detached from the building.

Thom Walker
06-12-2007, 09:45 PM
I feel like a panelist on I've got a secret. Is it safe to assume drainage was away from the slab and that grade level was below the sill? Did the slab slope toward or away from the garage door?

Frank Bombardiere
06-13-2007, 06:01 AM
Drainage was fine. I recommended that they get the sprinkler system checked and to get a general contractor to do some more investigation to find the source of the problem. Thanks for the replies.

Frank Kunselman
06-13-2007, 10:09 AM

What is the exterior covering? Are there any windows? If siding, did the bottom lap below the top of the stemwall? If brick wainscot, is there flashing under the brickmould?

Do you have an exterior pic?

Frank Bombardiere
06-13-2007, 01:01 PM
It was a bric veneer exterior and this was going on all the way around. No windows.

Jerry Peck
06-13-2007, 03:47 PM
It was a bric veneer exterior and this was going on all the way around. No windows.


The secret words!

Water goes through brick, no weep holes (or blocked weep holes), no through wall flashing (or improper through wall flashing), water runs down inside of brick veneer and has one of two places to go - outside or inside, being as the brick/mortar impedes the water flow more than the interior of the wall does, it goes inside ... at the bottom ... where one would expect it to under those conditions.


Frank Bombardiere
06-13-2007, 08:19 PM
Sounds like we have a winner. That is the most feasable explaination I have heard yet. Kinda what I was leaning towards. Your are right, there were no weeps and as I said there was a sprinkler system which was wetting the brick regularly. There rear side had a deck against it which is likely holding moisture underneath that is wicking through as well. Does not sound like an easy fix. I suppose cutting some weep holes would allow some drying, but the lack of proper flashing will be an issue.

Jerry Peck
06-14-2007, 05:36 AM
I suppose cutting some weep holes would allow some drying, but the lack of proper flashing will be an issue.

Also, "cutting some weep holes" is not as easy as it sounds ... remove a brick, remove the mortar behind it, re-lay the brick with bed and top mortar, but no head mortar - those become the weeps. But that only works *if* there is a proper through wall flashing and that brick is on that flashing, not higher and not lower.