Comparing Top Plate Gasket Application Options to Meet Code Updates
Having performance problems? Trouble in the bedroom? Try installing a top plate gasket.
Whether your leakage is in the bedroom or another location, a top plate gasket application may be exactly what you need to take care of those nasty cracks or gaps causing you to fail a code inspection or blower door test.
The Problem with Wood
Maybe I’m wrong, but wood today doesn’t seem to be as good as the wood from years ago. It may just be my memory, but it feels wetter. Even the stuff that appears to be dry seems to warp before I get it framed up into a wall.
The point of all of this is when the top plates of the walls are warped, it may lead to:
- Missing chunks
- Unwanted air paths
The challenge is creating a seal between the attic and the conditioned space. Combine damaged wood with framers who are in a hurry, and quite often we are left with imperfections where the drywall meets the top of multiple walls in a structure. In some instances, these imperfections can be the greatest leakage point, causing a failure to meet the code’s ACH requirements.
Creating a Seal
As an insulator, fixing air leakage at the top plate is easy. If I am using spray foam, I am sealing this area from the top. I can either spray the attic floor or roof deck. If I am using air permeable insulation like fiberglass or cellulose, then I would install a gasket at the top of every wall in the structure to provide a seal between the drywall and top plate framing members.
Any of you building to Energy Star 3/3.1 version 08 realize top plate gaskets are nothing new. However, as more states adopt newer codes, many builders are struggling to meet the required 3 or 5 air changes for their area.
In the past, there weren’t many options for top plate gaskets. Early adopters mostly tried to use caulking, but air sealing drywall to a top plate had many challenges. Today, there are several options, and top plate gaskets have proven to be one of the best ways to meet new code-required numbers for airtight wall construction.
Let’s start with inexpensive and easy. Rim Seal by Owens Corning, and other products like it, are rolls of a thin foam that is stapled or adhered to the top plate. They can be installed under netting, but when installed in applications where they are not covered over, the process of installing the drywall may strip or damage the product.
Another solution is to train drywall installers to place the top edge of the drywall over the gasket at the top of a wall rather than sliding it up a wall. This process might work for a while, but it is harder than sliding the sheet up the wall. Old habits often return without ongoing supervision.
More recently, DOW brought its Great Stuff Pro Gasket seal to market, which is applied much like the gun foam so familiar to our industry. Even though it looks the same as gun foam, there are some differences to keep in mind:
- This product is water-based and requires a special gun – If you were to use another, the product would rust or clog the gun and become useless.
- It’s important to shake the can vigorously – There is a mixing ball in the can that takes serious effort to dislodge and mix the product.
- Installers should pay attention to bead structure – When it begins to change, it’s time to shake the can again.
As a last note, the product does need 6-24 hours to set up and cure before the drywall is installed. Prior to curing, compressing the foam will cause it to flatten and compromise its ability to rebound. With the right preparation, Great Stuff gasket seal will yield 360 linear feet when applied in a ⅜” bead or 200 LF when applied in a ½” bead.
If there are other products you would like us to review, please let us know. We look forward to earning your business every day.
BY KEN ALLISON
KEN SPECIALIZES IN BUSINESS DEVELOPMENT AND BUILDING SCIENCE. YOU CAN FIND HIM AT ANY OF OUR TRAINING EVENTS AROUND THE COUNTRY HELPING LOCAL CONTRACTORS GROW THEIR BUSINESS. CONTACT YOUR LOCAL REP ABOUT THE NEXT TRAINING EVENT NEAR YOU TO HEAR KEN’S ADVICE FIRST HAND.