# Remedying Water Wicking Up Slab Foundation Wall of Barn



## maddy (Oct 30, 2010)

I am a single lady, homesteading on my own and hoping that some of you guys with expertise in construction might give me some guidance. I have a shop-quality barn with a concrete slab foundation and a gambrel roof. The barn is located in an area that receives quite a bit of underground run-off from a nearby slope.

This last spring, which was unusually wet, the area around one side of the slab foundation became quite soggy, and I found seepage of water onto the interior concrete floor on one side of the building. (I know that the water was coming from below, as opposed to coming down the wall from the roof, because the wood sheathing underneath the corrugated metal siding is water-marked and degenerated only along the bottom two feet.) This problem has been a hard one to get a handle on because the floor of the barn is raised approximately 4 to 5 inches above the level of the surrounding soil, and there is another 8 to 10 inches of foundation below ground. It's hard to imagine that water can travel up concrete that far.

We're now halfway through July, and we've had exceptionally hot weather for several months now, but the area along one side of the barn remains quite moist. Yesterday, I dug down about 8 inches around the affected side of the barn, clear to the bottom of the foundation. (There was no footing, and at the bottom of the foundation I could see that there was pea gravel underneath the slab.) The excavated material was heavy clay loam, and I could see that the foundation wall was wet where the soil had been removed.

My first thought was to backfill the trench with 1" drain rock so that water-logged soil would not be sitting right up against the concrete. It then occurred to me that this might simply draw water into the space around the concrete from the surrounding soil, making the situation worse.

I then began thinking about a French drain along the affected side of the barn. However, the land around the barn is flat, and if the drain were placed along the very bottom of the foundation, there would be no place for it to "daylight." I got to wondering if I could extend the trench another 10 or 15 feet and create a sort of catch basin by digging a hole and filling it with rock. Maybe I wouldn't even need the catch basin if the rock-filled trench were sloped away from the barn and extended 10 or 15 feet past the barn.

I'm kind of stumped. I'm doing this all by hand and need a solution that doesn't involve a great deal of expense. I would be grateful for any ideas or advice you guys have. Thank you!


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## FireMaker (Apr 3, 2014)

Time for some exercise. We had similar water issue this winter. We had water come down off a hill and pool, freeze, repeat. It was a mess. In the spring I started digging a trench to redirect the runoff. I still need to expand the trench due to the amount of water. 

Then we will see how it goes next year. Modify as needed and do it again. 

I think the most important part is minimizing the water that can approach the building. The have some drain pipe around the foundation taking what is not redirected to a low area.

Best of luck


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## maddy (Oct 30, 2010)

Thank you, FireMaker. I'm in the process of redirecting drains to reduce the amount of water that gets near the barn. I guess I'm looking for a "belt and suspenders" approach, thinking that there might also be something I could do directly around the foundation.


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## Steve_S (Feb 25, 2015)

I believe the French drains are a definite "part" of the solution but possibly a small swale slightly higher up & away towards where the water flows down from will also help redirect water away. Deflecting water is a pain but not a crazy task, just observe what is going on around your structure. Drainage Tile (4" pipe with silt sock as used on farms) in gravel trench works fairly well (as long as you don't drive over it or put loads on it).

Disturbing the soil immediately next to the slab, will loosen the soil and essentially create a place for water to go, ensure you compact it very well, so you don't create another problem.

Eaves troughs will also help deflect water away or for capture to use in gardens... You can be pretty sure than any water within 24" of the base foundation will find it's way to it, ideally you want to deflect at least 2' away from building sides.

Without seeing the lay of the land how the building is set into it and knowing where the water is coming from and going to, it's a tough one, as much of this depends on the observations of what is going on.


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## Skamp (Apr 26, 2014)

Gutter?


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## melli (May 7, 2016)

Trying to get a sense of what you have for foundation? You have a slab floor about 4-5 inches above grade, and when you dug around perimeter you didn't hit a footing? Do you have a mono slab (where slab floor and wall support are one)? In a mono slab, the edges are much thicker to support the walls. I find it hard to believe one would do a 'pier' foundation wall without spread footings in your soil type. 
I've done remedial work on garages and the like because no drain tile around perimeter of building. And clay/silt around a building is asking for trouble. Clay/silt hold water, and that soil type is conducive to hydro-static lift (capillary action). It draws moisture up. 
I like your idea of digging a trench up against foundation, and filling with drain rock...I really would consider throwing in PVC drain tile pipe (cheap). Don't need much of a slope. The rock and drain pipe break the hydrostatic effect along wall. The pipe will drain bulk water. And, finally, throw some landscape fabric over the rock and pipe so none of the fines get back down a clog up your work. And any topsoil you use around barn, high sand content, or drain rock. 

Also, be aware that if you don't have gutters, water may be splashing siding...when it hits ground, it sprays sideways (and up), and I've seen water damage that you describe on sill plate and lower foot or two of wall. 
The moisture on concrete floor is usually hydrostatic lift of water. Not enough drain rock/sand under slab or around edges. 

I feel for you, digging through that type of soil is the worst. I've used a long crowbar to loosen up soil.


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## Skamp (Apr 26, 2014)

I'm with you on the gutter. This sounds like a classic case.


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## melli (May 7, 2016)

Here is an example of water spray coming off roof (no gutters). It hit a woodshed, and splashed on siding (same effect as hitting ground)...it got underneath siding, and once it did that, it almost caused the cantilevered chimney to leave said house. 
Interestingly, the siding looked ok, just a slight telltale sign of mold on trim. Owner figured just the trim need replacing....haha...was he surprised. 

I take off trim and see this...I recommended he rip it all off.









And this is what was underneath,










Left corner was water hitting shed and splashing onto siding....right side was water coming off roof and hitting siding. 
The chimney chute was cantilevered out from house, so had no eaves. Nasty...a petri dish in there. Can see floor rim joist only attached at middle. And all the joists, except two middle ones, were rotted (no longer supporting chimney). 

Must show final result...lol


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## Darren (May 10, 2002)

The pea gravel underneath the slab should have prevented the water from getting to the slab unless it was filled with water. For future reference fume can be added to the concrete mixture to make it more water tight.


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