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Rot/mold on front porch

673 Views 10 Replies 5 Participants Last post by  Nealtw
I tried doing a search but couldn’t locate an answer.
A few weeks ago I dropped the drywall in my garage to add several electrical circuits to power my table saw, dust collector, etc. once the wall was opened up I found the sill plate and sheathing was wet. On the outside of this wall, is my front porch. The front porch is a cement slab that was poured directly against the tyvek house wrap. I found a small tear and patched it and then proceeded to try and dry the wall inside my garage using a fan. Two weeks go by and now the water is back. I dropped additional siding on a different wall and found worse damage. Sheathing was rotted badly and mushrooms were growing out the sheathing behind the tyvek.
I have to cutout the damaged osb, however I’m curious if there is a better way to seal the new osb besides using house wrap. I get a lot of wind driven rain in this area, and am not entirely sure the best way to reflash it.
My plan was to use butyl tape to wrap the bottom of the osb and up both sides. Then I’d come back down the new osb with a new piece of tyvek. I’d seal the small gap (1/32) between the concrete and thentyvek with a concrete caulk. I’d then reinstall the siding, and put caulk on the bottom of the jchannel that comes in contact with the concrete to stop the wind driven rain from getting underneath.
Any better suggestions out there?
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pictures from inside and out are needed.
There is a primer for Blueskin to stick to concrete and then cover that with a flashing.
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That looks like a good product. I’m limited to the j channel width before it becomes visible. Is 1” enough surface area for that to adhere properly to the cement?
That looks like a good product. I’m limited to the j channel width before it becomes visible. Is 1” enough surface area for that to adhere properly to the cement?
Put a flashing down, raise the J trim and cut the bottom of the siding to fit.

Think about it more like a head flashing on a flat roof.
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I have to cutout the damaged osb
So it looks like the slab covers up at least 10" of the wall sheathing on the house side (vs maybe more on the garage depending on stem wall height). How are you going to replace that sheathing, and how long has the water sat there to go thru to the rim joist or sucked back in to the sill plate there?
I never used blueskin. I once tried eternabond tape (with primer) but that was inside bsmt slab. You may want to ask the maker about the primer and the adhesive on concrete surface that will see water or high moisture with rain. In case of spot fails, more than one inch, I think, although with a good adhesive, that wouldn't matter much.



You can also cut a kerf in the concrete, straight line with a guide for best look, bend a flashing to fit into the kerf and seal with caulk. Then one inch is good enough. Also may want to seal the concrete surface.



Some water maybe also from the door (door track holding water?) and wicking from the ground.
I got lucky and the sheathing is only about 3-4” down into the cement. I’m going to cut it out using a circular saw and oscillating saw. I have a circular saw blade intended to cut concrete left over from a job I did at my old house so I think I’m going to go the route of cutting a line and tucking the flashing into that and sealing it with some sort of caulk. I came across a video by Matt Risinger that recommended that method as well, plus I can get plus that matches the color of my siding so it won’t look out of place. I appreciate all of the advice
I got lucky and the sheathing is only about 3-4” down into the cement. I’m going to cut it out using a circular saw and oscillating saw. I have a circular saw blade intended to cut concrete left over from a job I did at my old house so I think I’m going to go the route of cutting a line and tucking the flashing into that and sealing it with some sort of caulk. I came across a video by Matt Risinger that recommended that method as well, plus I can get plus that matches the color of my siding so it won’t look out of place. I appreciate all of the advice
Do that but put the peel and stick in there too with the primer .

Your door should be raise 1 1/2" so it could get a similar treatment


You can be sure that blueskin will stick to most anything with primer
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