Australia Storm BookAfter The Storm - 20
Roof Repairs: The Rafters
GeneralA common roof consists of three layers of materials: sheathing, roofing felt, and shingles.
Sheathing is nailed to rafters before building felt and shingles are applied. If you have broken rafters and ridge beams (boards, poles), they must be repaired first. The strength of the roof depends upon a continuous rafter or truss extending from one point of fastening to another, and the full distance between fastening points must be replaced, if broken.
TipsA good repair may place the new rafter alongside the broken one, nailing them together; while on a truss, a replacement board would be scabbed on, overlapping the two points of fastening.
The size of the area damaged dictates other proper procedures. One or two broken rafters could be repaired with a small scab and truss configuration.
To further strengthen weakened areas, transfer loads of the roof to undamaged areas by using a 2 x 6 nailed beneath rafters extending across the weakened area onto the next two or three undamaged rafters on each side.
Broken, severely damaged rafters are seldom as strong after repairs due to less rigid fastenings. Further strengthening may be done by adding a prop nailed to the horizontal 2 x 6's with the other end nailed to a joist directly below.
In all cases, the size of wood used for repairs should be the same size (or larger, but not smaller) than the wood broken. A 2 x 6 should be used to repair or replace a 2 x 6 and so on.
If your roof is not tied to your walls and did not shift or blow off, tie it down now! Place a rafter tie at least each 4 feet and face nail it to the rafter with three 8d nails minimum.
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