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and seal it.

Be sure to turn off any lights in the attic and look for light leaks through the insulation. These light leaks are almost always air leak locations. Be careful around recessed lighting. Older recessed lights must not come into direct contact with insulation. You have to construct special housings that create an air space around the entire fixture before you insulate around it. Check with your fire prevention officer if in doubt about how to do this.

The building code in most places requires an air gap between chimneys and any wood framing. This gap can be a huge source of air leakage. You can stuff this gap up in the attic with fiberglass batts to stop air from pouring down into your home.

Inspect your basement for air leaks where the wood framing is in contact with the foundation. Air leaks here can be sealed with caulk from the interior during winter months.

During construction of a new home, air infiltration can be minimized with a comprehensive system and different products. It’s not a matter of just using a large air barrier on a roll and wrapping your home like a giant Christmas gift.

You need to think of your house as a boat. Imagine that the air around your house was water and how might it leak into your home. Every crack in the sheathing needs to be taped, the contact between the foundation and the sill plate needs a gasket, the flanges of doors and windows need to be taped to the sheathing or air barrier wrap, the contact points of wall plates and flooring need to be caulked, every hole in a top plate that leads to the attic needs to be sealed, and so forth.

Sealing a new house is all about attention to detail.