Roof Without Rafter Ties

In many situations you ll find that ceiling joists installed parallel to the rafters are intended to function as rafter ties.

Roof without rafter ties.

Gable roofs without ceiling joists provide a much higher and triangular shaped ceiling inside the home. And the roof covering material determines the size cross section area of the roofing timbers used. The roof framing mock up below shows a standard rafter tie. If you are framing a cathedral ceiling there are a couple ways to deal with the need for rafter ties.

Ceiling joists and rafters shall be nailed to each other in accordance with table r802 5 1 9 and the rafter shall be nailed to the top wall plate in accordance with table r602 3 1 ceiling joists shall be continuous or securely joined in accordance with table r802 5 1 9 where they meet over interior partitions and are nailed to adjacent rafters to provide a continuous tie across the. Without the proper support of rafter ties or a structural ridge a typical gable or sloped roof will sag downwards while pushing the building walls outwards towards a catastrophe. You can possibly remove them altogether of you include posts in the gable walls to support a structural ridge. Like rafter ties collar ties are horizontal members that tie the rafters.

If your garage is 24 feet wide and has a 4 12 roof the new rafter ties can be placed no more than 16 inches up from the plate without additional engineering. From a practical perspective it s difficult to use high rafter ties on a low pitched roof because the force in each tie increases with the inverse of the pitch. Collar ties collar ties are an alternative to rafter ties in framing where a conventional ceiling is not desirable. A rafter tie is a tension tie in the lower third of opposing gable rafters that is intended to resist the outward thrust of the rafter under a load.

The shape and size of a roof depends on the span and the floor plan of the building. Rafter ties or ceiling joists acting as rafter ties are required by code unless the house is designed so that the walls or a structural ridge beam carries the full load of the roof.