house band joist / sheathing – how to seal?

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Replies
if you dont have any kind of moisture barrier behind your vinyl and just seal the bottom section it will be like a band aid on a fracture.
vinyl is not weather tight so there is moisture/water that gets behind it. if whatever you end up using does not adhere to the sheathing well or for a prolonged period of time then you may just trap whatever water trickles down from above your sealed section.
did you remove the j channel for the pictures or is there none on there?
Yes, there is no moisture barrier on any side of the house.
Yes, I removed the vinyl starter strip. Under the starter strip there was L shaped flashing for holding vinyl cantilever panels. The L flashing was no longer needed so I removed it. I will install some drip edge and a starter strip or something like that.
i dont think you will benefit much from what your proposing unless you have a specific draft location you may be sealing off. although the way your siding is installed is far from ideal and could possibly need to be removed at some point to properly address your concerns, i think you would be wasting time and money by just adding some moisture protection to the bottom 18-24''. from what the pictures look like, at least the moisture that gets behind your siding now has plenty of air to dry it out and you would be slowing that process down by trapping it at the rim. my assesment, not my house and dont know what your specific concern is. there must be a reason why you began this process.
Installing a moisture barrier
.
What you want is an air barrier, to keep air from being sucked into the joints there. If the siding and soffit were removed it would make sense to wrap the edge and rim joist with housewrap. (Would make sense to wrap the entire house, but that's a different matter.) But it's probably not practical to retrofit that.