water leaking under wall sill

[wuanzinger]

I had a contractor put a small addition (9'x14') to the back of my garage for a sandblaster and storage. He poured a new slab and extended it to form a small patio. It was graded (perhaps not enough) and there is a drain in the middle of the patio, but water leaks under the sill and is being absorbed by the pressure treated sill. I can see moisture rising up into the wall studs. Obviously, this won't last very long if this continues.

I tried sealing with roofing caulk, and it has helped a little, but it is not a permanent solution and it still leaks a little. What is the best way of fixing this? Extend the eaves? Cut a small trench in the concrete for water to run away? Should this have been built with a short concrete wall instead of the wood right on top of the slab?

Thanks for you help. Great site.

 

[PAToyota]

What you've drawn will leak. Not much that can be done. The outside slab should have been poured lower than the inside slab so that water could not pool and run under the wall.

 

[Krodad]

If what you have drawn is accurate, you are kind of in a pickle.

If you have the option of building a shed roof over the exterior slab, to make a "lean-to" type of thing, you might help the situation. Maybe a wide, deep saw cut as close to the sill plate as possible will help channel away water, then flash against the sill plate, across the slab, then down in the saw cut (a straight "Z" seamless flashing) and you have a chance of mitigating the problem. You'll have to be sure and keep this saw cut free of debris so that it works as intended.

And take the guy that designed this thing to court.

 

[CraigFL]

Expanding on Krodad's idea... I would cut a channel in the slab as close to the sill plate as possible and flash into the channel and seal it with a cement filler or epoxy to keep the water out --- like an upsidedown chimney flashing.

 

[wuanzinger]

Thanks everyone for your help. It's much appreciated.

It is as I have drawn it; no step between the outside and inside. I will call the guy back and ask him to extend the eaves and cut a trench. Is there any building code requirement to the step down that I can reference in case things get more serious and lawyers become involved?

It seemed like it was an easy project, but somehow this 'professional' screwed it up big time. Why is it so hard to find someone to do good work?

Thanks again.

 

[PAToyota]

There are no specific building codes that would prevent that, but all you have to do is look at it to realize that water will run under the wall.

I know what you mean about "professionals" - there are several registered architects in my office that have done/would do just as poorly...

 

[Ironcrow]

Sorry for your troubles. This is fate's way of telling you to go ahead and roof over the patio, enclose the walls, and be done with it Besides, you needed a weather tight shed for that new air compressor anyway, right?

 

[sishelper]

Same problem on new attached entryway built over existing patio. Thanks for the ideas. More info would be appreciated. How big did you end up making your "z" shaped flashing etc. How close did you cut your channel and how far did you put your flashing up the stud wall sheathing? Thanks.

 

[Falcon67]

Extend the eve, run a gutter and that will move a lot of the water away. Had that problem in the last shop where the slab contractor poured it on grade instead of up 4" like I asked. I don't know that flashing will help that much, even with a small channel. The only way to cut that close to the wall is with a hand held cutoff tool and that's not going to work very well. Pull the siding, run 6" wide galvanized flashing flush with the slab and caulk that seam, then put the siding back. The gutter will do most of the work except for a storm that blow rain right at the wall, just keep it clear.

 

[NUTTSGT]

A single layer of block would have solved that problem in the beginning.