Roof Truss Problems

Interior Damage

• The first indication you may have that something is awry with your trusses is the appearance of cracks at the edge of the ceiling or a gap between the top of the wall and the ceiling. These problems occur where the ceiling meets an interior wall. Using new or “green” lumber can cause the trusses to move as they dry out. Heat and humidity are also major factors in shifting trusses.

Truss Uplift

• Roof trusses contain supporting boards that extend between the top chord and the bottom chord to sustain the roof load. Unfortunately, wood, being a natural product, will move when subjected to temperature fluctuations and humidity changes. The trusses, designed to span the width of the house, attach only to the load-bearing points, leaving the rest of the truss free to move. As the wood contracts, the center of the bottom chord can lift away from the top of interior walls.

Limited Attic Space

• Unlike a stick-framed roof that has an open attic, typical roof trusses leave no open attic space, which prevents most types of remodeling in that area. If you want to install a large skylight or construct a loft, you might not be able to since cutting through even one roof truss member will void the truss warranty and compromise the load-bearing integrity of the truss system.

Prevention

• Reducing heat in the attic may reduce additional truss movement. Heat rises, so install attic vents to draw out hot air. Ask your contractor about installing floating drywall corners that allow the trusses to heave without cracking the ceiling drywall. In some cases, you can camouflage the crack by installing wide crown molding around the top of the ceiling. If you must cut through trusses, call an engineer for advice on how to stabilize the remaining truss members.