Roof Truss Issues

Arched roof trusses moving in response to moisture temperature variations across the truss can lift the building ceiling sufficiently to cause nail pops or actual tears at the ceiling wall juncture.

Roof truss issues.

The construction concerns article dated february 13 2013 discusses the roof trusses of an 1840s grain elevator with a pitched roof shaped like a capital a. A broken roof truss can cause many different problems. They should not be nailed to a wall using 16 penny nails. The best way to check if a truss is bent or deflecting is to use either a string line or a laser level and use the truss support as the datum.

These areas of the roof subjective to compressive forces oftentimes face roof support problems such as the truss members buckling or distort out of a plane and unless they are properly braced to hold them tight during erection the entire truss may warp up and distort out of a plane. Damaged or missing gusset plate it must be intact and free of corrosion. If you see nails they must be pulled and the special truss clips installed in their place. This can lead to structural issues and occasionally the roof sagging.

If the truss is bad enough it can cause the sagging or collapse of a roof. Roof truss uplift can be diagnosed as the cause of nail pops and cracks or separation between the ceiling and wall top. If the drywall can t move enough to accommodate the warp it cracks away from the wall. Dry wood shrinks moist wood expands.

Roof truss uplift occurs when the bottom chord of the truss is exposed to significantly different moisture and or temperature conditions than the rest of the roof truss. This problem occurs occasionally with roof trusses. The upper members of the. Should a decision be made to modify a truss in order to raise the ceiling in an area allow more storage or move a stairway then it is wise to consult an engineer for assurances that there is no structural issues.

The good news is that the problem can be fixed fairly easily with a few materials a helper and diligent application of the steps below. 3 defective lumber sometimes a knot or check in the lumber of a truss is intact and appears structurally sound when the roof is installed but pops open later. Resin dripping from the wood as in the photo below is ugly but not a structural defect. Because the bottom chord of the truss is buried in heavy insulation it experiences different conditions than the top chord.