What is causing moisture issue with basement sill plate?

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Posted by: from Edmonton
5/18/2015 at 11:36:39 AM

I have a 10 foot section of sill plate in my basement, that has a few small areas that have been consistently moist since we moved in (about a year). The accumulation did not track from anywhere in the wall and appears to be coming up directly through the basement floor or a gap between the sill plate and concrete floor. This has me worried that there is not a proper barrier in place between the sill plate and the concrete.

I've attached a few pics to give you a better idea of what I'm talking about. The 1st picture is a close-up shot of one of there moisture areas and the 2nd picture is a large view of the same area. The 3rd picture is an area under the stairs which also runs along the sill plate. As you can see there is quite a bit of efflorescence.

Has anyone ever seen or dealt with this kind of thing before? Any idea what a repair like this could cost? Any information you could provide would be greatly appreciated.


What is causing moisture issue with basement sill plate?
What is causing moisture issue with basement sill plate?
What is causing moisture issue with basement sill plate?
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Date/Time5/18/2015 at 12:47:08 PM


It will sound funny at first but, it is called hydraulics.

The water table around your house is pushing water up through your concrete, it will find the path of least resistance.

Because your problem is from outside water, I would recommend you solve this problem first, then you could use a product called xypex or similar to seal the cracks in your concrete better.

To fix your outside water table or water pressure, means to get the excess water away from your house. You could try to clean your drainage pipes with a special pressure washer head. I would call in a professional to do this.

If that doesn't solve your water problem then you need to look at new or better perimeter drainage.

When doing so, get three prices. The cost will scare you a bit.


Wayne Balliet

Project Manager

Builtru Construction

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Brian from Next Restoration in Rockwood
Date/Time5/18/2015 at 1:48:43 PM

Yes, I have dealt with this. It's a high water table forcing water up through the concrete or your drainage tile is compromised. If you have one, do you have a sump pump in your floor? If not I would suggest putting an internal drainage system inside the basement walls going to a sump.


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Jm in Edmonton
Date/Time5/18/2015 at 2:16:26 PM

Thanks for the responses.

I do have a sump pump in the basement that works well and the weeping tile around the house, that appears to drain into the sump pump at a good pace during spring melt and heavy rain. This small area is the only place where small amounts of moisture seem to accumulate, which is why I was questioning the sill plate barrier. I literally have no moisture accumulating anywhere else in the basement.

Would it be a big job to remove the plate to get a good look at what is underneath it?

Also that sill plate is actually buried into the concrete an inch or so, while all the other ones rest nicely on top of the concrete. Could this be a source of the problem?

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Date/Time5/24/2015 at 11:51:46 AM

High water table is the actual source of your moisture problem. However having the sills in the concrete is a no no. Surprisingly the city passed your house. More than likely there is no concrete under those sill plates, which means they are sitting on gravel or worse bare earth. So they are sucking up the moisture from the ground and this is the weak spot in your floor where water will come up. It's like having a hole in your waterproof floor. You will have to support that floor and remove the sill plates and concrete that area before putting the wall back.

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