Seal and Inspect HVAC Duct and Trunk Termination

Seal and Inspect HVAC Duct and Trunk Termination

Eric moves on to inspecting the HVAC trunk terminations, deducing where sealant is necessary and how to go about properly securing the building envelope in the process.

So we’re just about done sealing all the can lights and next I’m moving on to the trunk terminations — HVAC terminations.

What we want to do is make sure that the registers and supplies are sealed to the drywall lid as well, so same practice that we’re doing with the can lights, but we’re just going to check every single trunk termination.

We’re looking at an HVAC supply that’s obviously heading to the living space and it’s going  through some plywood on the floor here. So we’re actually not able to get all the way down to the drywall in this instance, so what we’re going to do is we’re going to seal this trunk right here against the drywall, but in this case we’ve got to use a caulk and here’s why. If we use an expanding foam, this foam will expand. It’ll adhere to this plywood, and it has the potential to crush this soft duct, so you just have to make sure that you’re using the right materials for the right purposes when you’re air sealing. We’re just going to go ahead and caulk this one.

So here, we’re looking at a HVAC supply termination and you can see that there’s a box located on the drywall and this is what we’re actually going to seal to the drywall to make sure there’s no blowback from that conditioned heated or cooled air back up into the attic. So Thomas is just going to foam the seal around the box right here. We’ve shown you already how to seal a soft duct if you’re in that scenario, but this expanding foam is perfect for sealing around the box here.