Attic Wind Braces

For the purposes of this chapter the guidance and use of standard trussed rafter bracing does not apply to homes on or near exposed sites e g.

Attic wind braces.

7 2 9 bracing for trussed rafter roofs trussed rafters shall be suitably braced to support applied loads and self weight without undue movement. Item 863694 model tob12sbr. Air vent airhawk 12 in aluminum externally braced roof turbine vent. The purpose of attic bracing is two fold.

Diagonal bracing remains a vital interior part of many roof systems and in wall wind braces are required by building codes in many municipalities or by individual state laws in the united states. Purlins as shown in sample photos below are installed for rafter support. An important notation is that the purlin bracing should be off of walls or beams as needed. If the wind load is high enough and the vertical studs are long enough the frame may also require a brace to prevent it from rotating the frame and or buckling the verticals see figure 1.

In architecture wind braces are diagonal braces to tie the rafters of a roof together and prevent racking. In medieval roofs they are arched and run from the principal rafters to catch the purlins. Wind bracing keeps the roof trusses upright and square to the roof basically they stop the roof from being blown down when its being constructed but more importantly when its tiled. Get up into the attic and nail or screw a pair of 2x4s in an x pattern one extending from the peak of the gable to the bottom center brace of the fourth truss and the other from the bottom center of the gable to the top center brace of the fourth truss.

If its a truss roof then wind bracing is important when they design the roof they also design a wind bracing plan so the wind braces are positioned correctly. Special framed shear walls are becoming more common to help buildings meet the requirements of earthquake engineering and wind engineering. The braces struts or kickers should be within every 4 and should not be at a greater than a 45 degree angle towards the roof slope lower side. Over time these forces can cause the roof to begin to sag eventually leading the roof to fail if not.

Second it helps to straighten the roof plane if done properly. First it takes some of the sag deflection out which must not exceed the allowable limit.