Exhaust duct wall caps

[Michael Brown]

In Florida, we have been running exhaust ducts through the exterior walls where it is sealed to the house wrap or otherwise waterproofed in some manner. After the siding, stucco, or brick is installed, we return and cut the duct off even with the finish and install the wall cap. The cap is screwed to the wall and silicone is used on the top and sides to seal where the cap meets the wall. We have an inspector wanting us to cut our ducts off short of the penetration and when the exterior is finished, seal a short piece of pipe to the back of the wall cap and insert it in the penetration location and connect it to the duct. We feel this will be an infiltration point for moisture as there will be no way to effectively water proof the penetration. I have been unable to find any code language that supports either method so I am hoping someone here might have a recommendation. We would rather not do this if it is not required by code. Thanks.

 

[klarenbeek]

Kind of hard to do that if the drywall goes up before the exterior finish is done.....
How do the caps you are using attach to the pipe? a lot of the ones I see are friction fit, so if the pipe is secured in place so it can't push back, I would not have a problem with the way you are doing it. In fact I see it done that way a lot on apartments.