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Roof trusses

Attic truss

An attic truss leaves an open rectangular space in the middle of the roof, so the loft can be used as a room.

Also known as attic truss, room-in-roof truss, room-in-attic truss, bonus room truss, habitable roof truss

Instead of webs crossing the whole roof space, an attic truss has walls and a ceiling built into the truss itself: short vertical posts, a floor made by a heavy bottom chord, and a collar across the top. The members are larger because the bottom chord carries a floor load.

The truss is known as attic truss in North America and as room-in-roof or room-in-attic truss in the UK.

Related terms
Queen post trussA queen post truss has two vertical posts instead of one, which lets it span further than a king post truss. Gambrel trussA gambrel truss gives a roof with two slopes on each side, a steep lower slope and a shallow upper one, as on a traditional barn. Truss typesRoof trusses come in many shapes, such as fink, mono, attic, scissor and girder trusses, each suited to a different roof form, span or use of the roof space.
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