Hello!
When constructing a new dormer on a house and needing to modify 2 rafters, it is often recommended to reinforce the rafters that are closest and bear higher loads after the dormer.
Is it the rafters on the same side as the dormer that need reinforcing, or is it both rafters?
In other words, is it usually sufficient to brace the rafter with double rafters only on the dormer's side?
Best regards,
When constructing a new dormer on a house and needing to modify 2 rafters, it is often recommended to reinforce the rafters that are closest and bear higher loads after the dormer.
Is it the rafters on the same side as the dormer that need reinforcing, or is it both rafters?
In other words, is it usually sufficient to brace the rafter with double rafters only on the dormer's side?
Best regards,
This question does not have a general answer. You need to know the dimensions of the trusses, c/c distance, roof pitch, roofing material, any other material affecting the roof construction's dead weight, and the building's location in the country (to calculate snow load). If the rafters are oversized (e.g., to accommodate insulation or because it's an older house), it may happen that reinforcement is not needed. If the dormer fits between existing trusses (normally c/c 1200 mm), you usually do not need to do anything.