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Need to Air Seal Rim Joist on top of existing Block Wall

eoppie | Posted in General Questions on

We are building a second story addition on top of an existing CMU Masonry Block structure in Central Florida.  Exterior will be stucco.

The framers are installing a bead of adhesive sealant between the bottom of the rim joint and the masonry block, however it isn’t filling the gap completely.

My plan is to seal the transition between the OSB Rim Joist and Concrete Block with Visconn Fibre, filling the void at least halfway and then over spraying the bead.

We are using Zip for wall sheathing above the rim joist, which will be taped between the two transitions.

Should I also plan on taping the joint in between the OSB and Concrete Block?  Or is the plan to simply use the Visconn sturdy enough?

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