An attic truss is a specially designed roof truss with a modified web configuration that leaves an open, rectangular space within the truss’s interior, specifically engineered to provide usable floor space for storage or, with appropriate design, even finished living area within what would otherwise be a fully webbed truss.
This design intentionally reroutes the diagonal web members around a central open area, rather than filling that space the way a standard truss configuration typically would.
Because attic trusses need to support additional live load if the space is intended for occupied use rather than light storage, they’re engineered to a different, more robust standard than a standard truss carrying only roof loads.
What Does an Attic Truss Involve?
- A modified web configuration leaving open central space
- Sizing for either storage load or occupied living load
- A flat area providing usable floor space
- Sloped sides following the roof’s pitch on either side
Why Are Attic Trusses Important?
By leaving open, usable space within the truss structure itself, attic trusses provide homeowners with valuable storage or finished living area without requiring a separate, more expensive roof framing system, effectively getting additional square footage from space that would otherwise be inaccessible within a standard truss’s web configuration. This efficiency has made attic trusses a popular choice for homeowners wanting bonus space without the cost of a full second story.
Confirming whether an existing attic truss was designed for storage-only loads or genuine occupied living space matters significantly before finishing that area, since exceeding the truss’s intended design load could compromise its structural performance.
Attic Truss vs. Scissor Truss
An attic truss creates usable interior floor space through a modified web design. A scissor truss instead creates a vaulted ceiling effect by sloping the bottom chord, addressing an entirely different design goal despite both being specialized truss variations.