Sealing top plates, Building Gasket, what’s this all about you ask ?

Building Gasket 101

Building gasket has been my secret weapon since 2007-2008. I have been recommending this product to anyone who cares.  Anyone who has done this, along with other recommended measures was always able to have the home measure under the coveted 3ACH50.

I discovered its value while building a small subdivision in Ridge NY. Every home built to Energy Star standards prior to this was able to reach between 4 and 5 ACH50. As these homes were built to meet the LIPA Energy Star V2 minimums, 5ACH50 or less was a requirement.

Somewhere around this time I had heard that the IECC would require 3ACH50 and was quite concerned. All of the measures used to that point would never drop the homes to 4ACH50, never mind the 3 ACH50.

While we had caulked our drywall to the top plates, the great unknown factor was , how well of a job was done by the drywall contractor. Additionally, If the Sheetrock was slid right, left up or down after placing it on the wall I couldn’t see how any type of caulking would have worked.

Searching the web for building gasket landed me at the Conservation Technology web site. After finding their product,  BG-34 I ordered enough for 4 or 5 homes.

Low and behold, a few months later, every home tested out well below 3ACH50 !

Without this cure, here is what I have seen just after blower door testing…

The area it fixes viewed from the attic

The video to follow shows how air paths can be found when using a blower door. This entire clip was show while on the 2nd floor of a home. There must have been a few leaky rim and band joists for the air to enter between the 1st floor ceiling and floor above.


Further on in this video you see air shooting out of a door striker plate. Building gasket properly applied would have solved all of this.