How To Air Seal Ceiling To Wall Connections In Attics

In this video series we re going to show you some simple techniques and off the shelf materials that you can use to air seal up most all of the air leaks that you ll find in an average attic.

How to air seal ceiling to wall connections in attics.

Ventilate the attic 1 sqft per 300 sqft of attic floor space balance at ridge and soffit areas. So we re not going to see the top plate of the framing. Air sealing the attic perimeter. Occasionally they ll put adhesive on the walls but usually they ll glue only the studs not the plates.

What we ll do is we ll seal that block to the drywall and that ll get almost all of the air leakage that s going to occur. If you have an attic ac unit you should take this opportunity to check the air seals on the duct work. Sealing the ceiling so the attic insulation can work. Plug all open joist spaces under insulated side walls.

Fold the bag over and stuff it into the joist space under the wall. The best way to shut these huge leaks off is to sheathe over them at the framing stage. It s usually the hardest place to air seal because the cramped space underneath the eaves where the roof rafters rest on the outer wall makes it hard to move your hands and head. Mastic sealant paste is a slightly more effective and durable than hvac foil tape.

Long piece from a batt of fiberglass insulation and place it at the bottom of a 13 gallon plastic garbage bag. Attics often have other huge openings that many builders don t see as air leaks. When the furnace or air conditioner is on check for air leaks around the duct connections with your hand a lit incense stick or a thing piece of toilet paper. For a partition wall that runs parallel to the floor joist there s usually going to be some blocking in the ceiling.

Then insulate to at least the current energy code not only to the proper r value but also to grade i quality. Loose connections should be clamped taped and caulked. Use mastic sealant or aluminum foil tape not duct tape to seal all of the duct connections. Air seal all penetrations and possible leakage paths.

After the drywall hangers get the ceiling done they come back and do the walls. So simple a solution. Consider swapping out or upgrading any duct work that is not insulated properly. If they d simply run a continuous bead of adhesive on the top plate too they d block the pathway for air to move between attic and walls.

We re going to show you how to seal up light fixtures in the ceiling the junction box for ceiling mounted fixtures as well as recessed light cans. Heated rooms built into attics often have open cavities in the floor framing under the walls.