Pitched roofs

7.2.10Strutting for attic trusses and cut roofs that form a floor

Strutting to attic trusses shall be provided to support the applied loads and self-weight without undue movement or distortion.

Strutting should be provided:

  • in accordance with the design
  • where the span between the node points which form the width of the floor of the attic truss exceeds 2.5m
  • where the span between the supports to a floor within a cut roof exceeds 2.5m
  • using herringbone (38mm x 38mm timber) or solid strutting (a minimum of 0.75x the depth of the floor and a minimum of 38mm thick).

Table 5: Provision of strutting

Span of floorRows of strutting
Under 2.5mNone required
2.5m-4.5mOne (at centre of span)
Over 4.5mTwo (at equal spacing)