Owners of a classic brick Colonial in Duluth’s Congdon neighborhood had a spacious, charming third floor full of windows and light. There was one problem: the girls didn’t want to sleep up there because it was too cold.

Better World Builders used its blower door to depressurize the space in question and used a “smoke pen” to pinpoint air leaks. Pete and Leon found numerous “bypasses” — places where warm air could easily escape to the cold — in crawlspaces, at plumbing and electrical penetrations, between framing and plaster and around chimney brickwork.

A combination of expanding foam sealant, extruded polystyrene foam insulation and caulk plugged the leaks. A second blower door test showed much less air was leaking and allowed pinpointing of remaining trouble spots.

And the girls could sleep in their bedroom again.