Even these small holes can add up to serious energy losses in the average home. See what sealants work best, and learn some good tips in for plugging them up tight.

Even though light fixtures fasten tight to the ceiling, there's enough of a gap to let air flow through the many holes in a typical electrical box.

Learn how to identify which fixtures can be sealed directly and which ones need a custom enclosure to stop the air leaks. Plus, learn the right techniques for each type.

Conditioned air moving through light switches and other wall penetrations can find its way into the attic too. Seal where the drywall meets the top plates to solve this problem.

Get a quick review of the most common sealants — plus a few uncommon options — for sealing up holes big and small.

It's a good idea to keep all ducts in conditioned space, but if you can't, you should at least stop them from pulling dirty air from your attic into your living space.

Soffits and other large ceiling penetrations are essentially unintentional air ducts. Learn how to fit and seal foam to close up even the biggest holes in your attic.

See two ways to keep air flowing from your soffit vents to your vented attic if you're planning to add blown-in insulation between your ceiling joists.

Learn how to enclose the back side of a knee wall with an air barrier to make batt insulation perform better.