Air Sealing With Spray On Sealant

As conditioned air exits your home, outdoor air enters through small gaps throughout your home, attic, basement, crawlspace, garage or walls. On top of losing your already conditioned air, the outdoor air is bringing in water vapor, dust, allergens and many other pollutants which can leave you with an uncomfortable house with poor indoor air quality, that is more expensive to heat and cool.   

Where can you seal to protect your family against poor indoor air quality and save money on utility bills? Every house is different, so we recommend hiring a qualified energy auditor to test your house to tell you exactly where your house is leaking — and where air sealant is needed.

Areas of the Ceiling: Do you have ducts, recessed lights or electrical boxes in your ceiling? These are some of the most common leakage pathways in a home. Seal duct boots, recessed light housing or electrical boxes directly to your ceiling to stop leaking conditioned air and keep attic air where it belongs — in your attic. 

Top Plates of Walls: If you are going to be adding insulation to your attic, it could be beneficial to seal your drywall to the "top plates" of your walls, or the penetrations mentioned above, from the attic side before insulating. 

Basement Walls: If you have a basement, another common air leak is where your floor joist rests on the basement wall. Seal the inside corners on the top and bottom of this short “cavity” and apply another bead of sealant where the bottom “plate” rests on the basement wall. If you see daylight, or have penetrations through this cavity, seal those, too.

Electrical Boxes: Removing cover plates from electrical boxes and sealing the box directly to the drywall can help reduce air leakage, especially on walls shared with garages or other common spaces. If you have an attached garage, and your house-to-garage wall is open on the garage side, seal all penetrations and inside the plates to the drywall. 

Subfloors: Sealing your drywall to the "bottom plate," and your bottom plate to the "subfloor" can be your last line of defense against air leaks. 

NOTE: ASHRAE, ICC, and IECC recommend make up air once home is below 3ACH at 50Pa. Knauf Insulation strongly recommends hiring a qualified energy auditor to test your home before and after air sealing.