A School Addition – the Good and the Bad

I recently stopped by the construction site of an addition to a school not far from here. Foundations were in and backfilled , much of the steel framing had been erected, and the exterior steel stud walls were partially installed. There was one good thing about the portion of the building envelope that had been installed, and one bad thing.

First, the good. The structural engineer (from our office) used a detail in which the steel stud track hangs over the inside edge of the foundation wall, covering the top edge of the vertical foundation insulation, which is on the inside face of the foundation wall. These are not load-bearing studs. The sill anchorage is fine – a 5 1/2″ wide track still leaves plenty of width across the foundation wall for concrete screws. Take a look:

This will provide full insulation along the exterior slab edge. Way to go Dave!

The not-so-good involves the gap between the stud track and the top of the foundation wall. Not all the architects we work with understand the importance of creating a “sill seal” to maintain the air barrier continuity across this gap. On this project I specifically looked, and found it to be a GAPING void. Take a look:

Gap under stud track with no sill seal

Slipping paper in gap under stud track

If not addressed, this gap will result in significant air leakage for the life of the building. This is resolvable, but it’s much easier to seal the gap before the track is installed than after. This condition is the norm for probably 90% of buildings built in this country today. Call it a sad state of affairs – or a huge potential for energy savings.