Cause of water damaged sheathing under window

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Posted by: from Calgary
1/2/2016 at 4:45:45 PM

I have discovered some water damaged sheathing under my recently replaced new front window. There is brick in front of that. Can this possibly be repaired without having to remove the brick? The drywall removed from under the window was in decent shape.

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Date/Time1/2/2016 at 6:28:03 PM

It is difficult to give you a proper answer without seeing the damage in person or a photograph. Is the sheathing just water damaged or deteriorated ?

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Date/Time1/2/2016 at 6:44:42 PM

Hi John,

Most of the time you do not need to touch the bricks, you remove the window, repair the damage and reinstall the window.

At the same time look for the reason it happened and fix it so it does not happens again,

You may want to examine the caulking outside before removing it to see if there is a gap in it and that's where the water leaked in.

I hope this helps you.


Harry C.

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Date/Time1/2/2016 at 6:46:21 PM

Hi again John,

I'm not sure how the sheathing became damaged or how you actually found out without removing the brick. My best guess it that it became damaged when the "old" window was in place. Depending on the amount of damage, it is one of those "maybe" things. The sheathing seals the wall from the elements, but if it is properly covered with a house-wrap product, plus the brick, I wouldn't be too concerned. If it appears to be really soft or comming apart, sorry to say brick work will have to be re-done.

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Date/Time1/3/2016 at 3:39:43 PM


In my experience, which I have done plenty of exterior restorations, if it is simply stained. It should not be anecessary issue. To replace sheeting from the inside is a reasonable solution for rotting or deteriorated plywood. This could potentially compromise the structure of the brick if tie anchor or supporting iron angles are in the repair area. My suggestion would to solve the water infiltration problem to prevent more water getting in. Assess how much damage there is and if it merely staining,I would not worry about it.

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John in Calgary
Date/Time1/5/2016 at 3:15:44 PM

Attached is a couple pics. Yes the sheathing is in rough shape but mostly just in a couple spots. Where it is missing completely was partly from me poking around in there to see how bad it was, I did not find it that way.

Cause of water damaged sheathing under window

Cause of water damaged sheathing under window
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John in Calgary
Date/Time1/5/2016 at 3:23:41 PM

Hi Clodette,

Thanks for your reply. Yes, the damage is just under the window (as far as I can tell). And yes some of the sheathing is in pretty rough shape and crumbles apart if you fuss with it.

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John in Calgary
Date/Time1/5/2016 at 3:26:50 PM

Also, now that the pics have cleared, what's with the 1x4 on top of the sill 2x4 under the window. I have seen that under a couple of my windows, that can't be "code" can it?

Also making repair a bit more tricky...this is a 10x6 foot window.

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