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How to seal or flash between basement half wall and exterior wall?

3 years ago

last modified: 3 years ago

I'm in a split level and my 'walk out basement' has a found half wall that ends and continues as a regular wall. So there's 2x4 framing butting up against the end of the foundation half wall. The framed wall is sided, the concrete portion is just exposed concrete.

The 2x4 is rotted (mainly from the bottom) so I'm wondering how to seal and flash or generally protect this vertical exterior join as I replace it. My first guess would just be tons of caulk between them, then maybe a layer of vycor or similar on the exterior of the seam. Then maybe add some trim over the top of it all for good measure.

EDIT: Adding some pictures:

From outside, peeled back aluminum claddding a bit:

Inside view. I broke out as much loose rot as I could to get a better view. Jack+King studs on that door feel solid.

Featured Answer

PRO

Joseph Corlett, LLC

3 years ago

Pictures please. Caulk is not flashing.

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Comments (6)

PRO
Windows on Washington Ltd
3 years ago
+1. Gotta see what you are seeing. The answer is pretty easy and Joseph is correct. Caulking does not = flashing
Gregg z6a-CT thanked Windows on Washington Ltd
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I would use the money you are going to spend on the interior french drain and put it to better use by having the home waterproofed from the outside. Interior drainage eliminates seepage where the floor and the wall meet, but will do nothing to eliminate the transference of moisture through the walls. From looking at your pictures it is obvious that the initial damproofing that was applied at construction has failed. If you do not stop the moisture from the outside, it may eventually get worse, leading to cracking, more dampness and deterioration. We have waterproofed hundreds of homes that previously had interior french drains installed. Nothing you apply to the inside of the walls will work for any prolonged period of time. Waterproof to correct the actual problem, rather than install a water control system to deal with the symptom. Let the water in and pump it out, or keep it out all together. This is the main difference between waterproofing, exterior, and water control, interior.
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Technically 1" of XPS versus 2" of XPS would be about half the cost. So, is that worth the savings ultimately? I will not have in floor radiant heat for the basement. When you say slab I keep thinking you mean a slab built house, to reiterate, this is a basement and local code *here at least* does not require ANY rigid foam for the basement slab. Not sure if it even is required on the foundation walls. I guess this zoning ordinance is behind on code updates. -shrug- I see myself as one in a few that will be considering rigid foam for any basement application in new construction here. Is there any benefit to using XPS over the EPS for the foundation WALLS? I know I can get some EPS cheaper per R-Value but it will be thicker. I was thinking over 2" of EPS foam would be troublesome to fasten and then cover. Any recommendations on what to cover the foam with before backfill? Or should I only worry about covering the exposed foam on the walkout basement portion? I intend on using a waterproofing prior to installing rigid foam to the foundation walls.
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Gregg z6a-CT
Original Author
3 years ago
Added some pictures. Sure, I wasn't intending the caulk to be flashing, just an added measure. I was thinking something like vycor applied over the gap might act as flashing, since I didn't know how you could 'flash' a vertical surface like that. But that's was just a first guess... definitely why I'm asking.
Gregg z6a-CT
Original Author
3 years ago
For what it's worth, the little concrete pad landing pad outside that door is pitched away from that corner in both directions. But unfortunately chipmunks have managed to get into that corner (they are no longer with us) and there is no longer concrete directly under that rotted 2x4... I can stick a screwdriver down into dirt. I won't really know exactly what's going on there until I pull the door. The rest of the wall on the other side of the door is just a 2x4 wall with an untreated sill plate on-slab and it looks good as new from 1960. Just this corner is a mess.
PRO
toddinmn
3 years ago
The top and the sill are the most important and I would address those as well.I would foam or caulk the joints if they to small to foam between the door frame and studs and perhaps where it meets the concrete, you could also run a bead between the studs. You then use a flashing tape over it all but it won’t do much good and can trap water if the top is not done . If the door is remaining I would probably not worry to much about the sill, but the sill would typically be done first then the sides the top.
PRO
toddinmn
3 years ago
you Could also use a liquid flashing.

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