Problems With Trusses

Space

• The most obvious disadvantage of adding a truss to a roof is that it leaves less available attic space. The supporting beams of roof trusses obstruct access to attic space, so homeowners expecting to use the attic for storage may no longer be able to do so.

Insulation

• Certain types of trusses make insulation more difficult. A scissor truss, which is sloped and forms the shape of a hang glider or a splayed pair of scissors, is especially likely to cause this problem. Homeowners can try rolling back the roof to add more insulation, but this can lead to further problems in realigning the roof. Leaks can also arise.

Moisture

• Trusses also experience moisture problems. They are often exposed to moisture at the soffit points, the undersides of the supporting beams. Construction manuals recommend coating the supports with waterproof glue at the soffit where they will be exposed to moisture. If moisture condensation becomes a chronic issue, it may be necessary to install a mechanical ventilation system to alleviate the problem.