What is truss uplift?

Answer - Truss uplift is just what it sounds like, where the trusses actually raise up, which can create a gap where the ceiling and the upper edge of an interior wall come together. This happens in the winter. It's caused by the top chords of the trusses absorbing moisture from the cold air, making them longer, while at the same time, the bottom chords are kept warm an dry, buried in the insulation. With the upper chords growing, and the lower ones possibly even shrinking, the trusses arch up in the middle and lift off the walls.

Learn what to do about it on page 231