Roof Rafter Fixings

Rafter and joist systems are made up of two pieces of wood that run directly beneath the roofing surface and give it its shape while joists bridge the gap between the two rafter ends and support the whole thing.

Roof rafter fixings.

To fix the joists and rafters down on to the wall plates they should be toe or skew nailed to the top plate like below. If you re birds mouthing both top and bottom neither screws nor nails will add any strength to the roof all they ll do is locate the common rafters in their required positions. A collar tie is a horizontal piece of wood often a 1 6 or similar piece of dimensional lumber that is located in the top 1 3 area of the rafter span on a gable roof. They help prevent rafters from separating or pulling away from the ridge board or beam.

Birdsmouth joints cut into roofing rafters and mounted in place on top of the wall plate. Over time roof rafters can wear crack or rot and replacements may be in order. Roof rafter decking sagging. Rafters can also be damaged by a blow to the roof from falling branches.

Set out the ceiling joists onto the wall plates the ceiling joists are installed before the rafters as they will stop the roof spreading and also give something for you to lay planks across to stand on when building the roof. To cut roof rafters start by fixing the stair gauges on your framing square to the dimensions of your pitch. When considering what to do about sags in a roof start by noticing if the sag is in sheathing between rafters page top photo0 or sagging along the length of the rafters. The tha is a one piece joist hanger supporting trussed rafters and composite timbers from timber members.

Discussion in builders talk started by steveblewer mar 11 2009. Although the rafter must be replaced if it is completely broken smaller areas of damage can be repaired through the application of a scab board. However finding the requirements for rafter fixings in skillion roofs or for hip and valley rafters is a little more circuitous. This board is a section of lumber that is the same thickness as the rafter and 2 feet longer on each side of the damaged section.

This article describes a diy repair project using a site built spreader to straighten sagged roof rafters and decking. If is wasn t for this joint a rafter or roofing joist would only balance on top of the wall plate making fixing difficult not to mention the fact that there wouldn t be any solid connection between the roof and the supporting walls below. Finding fixing requirements for rafters in couple close roof construction is fairly straightforward in nzs 3604 2011 section 10 roof framing. It connects to rafters on the opposite side of the ridge board or beam.