Repair and Paint HVAC Manifold and Mastic Joint

Repair and Paint HVAC Manifold and Mastic Joint

As Eric works his way through properly air sealing the attic, he explains how to properly repair and replace an HVAC manifold and its mastic joint. Check out his analysis on how to effectively fix this common attic issue.


We’ve been working our way through this attic and the air sealing process. We’ve been air sealing trunk terminations, light penetrations, and all sorts of different types of things.

This is another reason why you guys need to be prepared. While we’ve been working on the attic, we discovered a mastic joint on this HVAC manifold that’s been compromised.

There’s HVAC tape that seals that joint and then they apply mastic overtop of that, and you can see here that this joint is completely compromised and they have conditioned heated and cooled air that’s allowed to leak out into the attic. So what we’re going to do is we’re going to clean up this joint and any other joints that look like that, reseal it with some HVAC tape and mastic.

We had shown you a manifold joint that had originally had HVAC tape and mastic applied to it, but that joint has been compromised and this manifold has been air leaking. So Steve’s already applied his HVAC tape and he’s just applying this mastic as you would with just a regular old paintbrush — simple project — easy fix for the customer that’ll make huge differences for your customers.