Exterior wall water damage


  #1  
Old 06-19-16, 06:27 PM
S
Member
Thread Starter
Join Date: Apr 2007
Location: Canada
Posts: 12
Upvotes: 0
Received 0 Upvotes on 0 Posts
Exterior wall water damage

Hi

I have this exterior concrete slab that has moved over the years closer to the wall and resulted in damage to the stucco and caused water damage/rot to the OSB and insulation. I took off the damaged parts (the concrete slab caused the studs to buckle a bit and i had to cut that back as well from the wall) and plan to redo the wall. The question is how to keep water away from the OSB/stucco as the slab is about 3-4 inches above the foundation. I think there is space beneath the slab and water should drain into that once its in the gap but i think i should do something along the bottom edge to keep the "base plate" wood safe.

Would appreciate any ideas.

Thanks
 
Attached Images       
  #2  
Old 06-19-16, 07:10 PM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Posts: 27,061
Received 1,910 Upvotes on 1,716 Posts
Well that's a terrible design!

I assume that tearing out all the concrete and lowering it by 3 or 4" or so is not an option? That would be best. If not...

I would probably begin by cleaning out the gap along the sill plate, blow it out with air, then put a 9" membrane over the studs (Vycor or Fortifiber Moistop) as a backup plan. Replace the sheathing on the wall. (Maybe use a treated marine plywood instead of osb). Then install fiber expansion board on top of the sheathing, between the concrete and the wall. Make sure the fiber board is about 1/4" to 3/8" below the level of the concrete. Then fill the gap with a pourable self leveling crack filler. (Loctite PL S-20 / Sakrete crack filler, etc) Don't over fill it, just try to get it level. Let that dry.

Then to flash the wall, you can do one of two things.

1). Pick out a galvanized flashing, preferably heavy duty galvanized, that is shaped like an L. If a hvac or metal/machine shop would make you something custom that works too. In the past I have used upside down / backwards gutter apron, but it had to be bent at an appropriate angle. Then run a HEAVY bead of sealant (again, a concrete expansion joint sealant, like Loctite PL S-10 or BASF NP1) on the concrete edge, far enough back that it won't gush out, and place the flashing into it, pressing it down firmly. Then nail it to the studs. Cover that with your wrb (foam or housewrap/stuccowrap, whichever one you have.) You would probably want to make sure that when the wall is re-stuccoed, that they use a weep screed to terminate the stucco ABOVE the cement, leaving an air space between the flashing and the stucco.

2). Almost exactly the same as above... but in the event that the concrete is too wavy and rough to install nice straight 10' long sections of flashing, you may need to make a kerf in the concrete. Chalk a line parallel to the sheathing... say 2" away from the studs... use a skilsaw with a diamond blade to cut a kerf, maybe 1/2" deep in the concrete. Then get a roll of lead sheet (you can find it online in various width rolls) and use that as your flashing, molding it to the shape by inserting it into the kerf first and just shape it/fold it with your hands. Maybe use a block of wood and hammer to lightly tap it, but be careful not to pierce it, it's very soft. Be sure it's blown clean before you do this. Caulk under it as described earlier. Then once you have it shaped, run a 2nd bead of sealant along the front edge to seal that kerf up.
 
  #3  
Old 06-20-16, 12:43 AM
S
Member
Thread Starter
Join Date: Apr 2007
Location: Canada
Posts: 12
Upvotes: 0
Received 0 Upvotes on 0 Posts
Hi

Thanks for the detailed reply.

I dont think tearing out the whole floor is going to be a good option.

I'm not clear what you meant by keeping the fiber expansion board 1/4"-3/8" below the level of the concrete and fill the crack. That would mean that the fiber board would end about 2-3 inches above the sill plate and the wall is now about 4 inches away from the edge of the concrete floor. Where would i exactly fill with the Loctite?

Are you suggesting that the concrete slab should be extended upto the wall so that any water stays on the slab?

Sorry if i'm a bit confused (this is all new territory for me). I've attached a drawing of what i'm understanding. (this is a link if you want to modify the image with MS Word https://drive.google.com/open?id=0B-...FFKTXU0T2VwVVk)
 
Attached Images  
  #4  
Old 06-20-16, 04:59 AM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Posts: 27,061
Received 1,910 Upvotes on 1,716 Posts
You have it drawn wrong. The flashing goes on top of the concrete slab. I didn't realize the concrete was 4" away, I thought you said it was tight to the stucco... looked in the pictures like maybe a 1" to 2" gap. Missed the part about cutting it back. That was probably unecessary.

The fiber expansion is a strip, about the size of a 2x4 that is 1/2" thick. It is installed horizontally between the concrete slab and the sheathing, so it will be entirely below the grade of the concrete slab. It is not another sheet of material that goes on like sheathing... it's just a horizontal strip.

If you have a 4" gap, yes, you might want to fill that gap with new concrete. Then seal the top of the expansion joint (which is about 1/4" below the surface of the concrete slab) with S-20 , then extend the metal flashing onto the concrete, setting it in a heavy bead of sealant (S-10) so that no water can ever get underneath the metal flashing.

You will still have groundwater to deal with, if that's a problem, which is why you almost always want the grade outside a house to be lower than the slab inside.
 
  #5  
Old 06-20-16, 05:57 AM
J
Member
Join Date: Jan 2011
Location: USA
Posts: 4,463
Received 128 Upvotes on 113 Posts
Building 101, siding needs to be at least 6" above finished grade!
That whole wall should have been built on top of at least one row of block and water proofed on the outside.
If I had to try and repair what you have there I'd use a shop vac to clean it up, sistering those studs with pressure treated wood at least 2' long, replacing that insulation at the bottom with foam board.
Bending some metal flashing so it runs up the studs at least 6" and extends out and over the edge the footing and bends down over the outside edge.
Using 5/4 X 8" X 16' long PVC lumber at the bottom of the wall set in a bed of silicone, with Z molding over the top.
There should have been a felt expansion strip between the slab and the wall.
The wall and slab never should be pined together, that slab as you've seen is going to move up and down, the wall should not.
Reflectix 4 in. x 50 ft. Expansion Joint for Concrete-EXP04050 - The Home Depot
 
  #6  
Old 06-20-16, 10:52 AM
S
Member
Thread Starter
Join Date: Apr 2007
Location: Canada
Posts: 12
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks for the replies.

I'm not sure what the person who put in the slab was thinking. That floor level is causing no end of problems.

@Xsleeper :The reason i had to cut back the concrete was that it was pushing into the wall and dented the studs and wall.

@joecaption: i like the idea of flashing as you described but i'm not sure if i can feel the edge of the footing to bend the flashing down without cutting the concrete back some more.
Does the the 5/4 X 8" X 16' long PVC lumber cover the gap between the wall and slab?
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: