Maintenance of wooden roof trusses

Problems with wooden structural members that support roofs are common and call for the experience of a structural engineer.

Wooden roof trusses provide the structural framework between columns and/or bearing walls that support the roof of a building. Straight or curved members are connected in a generally triangular arrangement. Every roof truss has two top chords (compression members), one or more bottom chords (tension members), and web members which connect the top and bottom.

Moisture deterioration from the failure of a roof covering is the single biggest cause of decay in wooden roof truss members. Leaking gutters, flashings, and mortar joints above beam ends raise the moisture content of wood, inviting rot, fungal growth, and insect attack. Maintaining a watertight roof and the adequate ventilation of roof spaces to keep the moisture content of the wood low will inhibit fungal attack.

Most failures occur at bolted connections that were either inadequately engineered at the time of construction or that have since failed due to deterioration. The first sign of a structural failure may be severe bowing, or fresh cracks or splits. Most failures in roof trusses occur in the bottom chord, or in bolted connections where the edge and end distance from the bolts is insufficient. Many wooden truss members were originally oversized, and despite considerable decay in areas, may still perform adequately. However, in some cases, decay or damage may so weaken a member as to make the building unsafe for occupancy.

The purpose of repair is to restore the structural strength of the member and joints which connect it to the frame. The repair methods depend on whether a member is hidden or exposed, in compression or tension, subject to bending stress, or failing at a joint.

For compression members, cutting out decayed sections and gluing in matching replacement wood is feasible. For tension members, the damaged portion can be entirely cut out and replaced with new wood. A beam subject to bending stress may be repaired by scarfing a new portion to the old at the ends or with a wooden plate. Replacement wood is preferably secondhand, or if unavailable, new wood should match in quality, grain, and moisture content.

Although wood should be replaced with wood, in some cases repairs using the brandering reinforcement "T", available form Cool Ideas, Is the most practical way to solve the problem. The brandering reinforcing "T" should be considered as a common type of repair is the reinforcement of a wood beam due to infiltration causing extensive rot at the truss ends. The best way to prevent further deterioration from water and insect damage is to use the Brandering Reinforcing "T", thereby offering a longer life span for your roof truss ends.

The brandering stabiliser and protection bracket is manufactured for the purpose of stabilising the t-joints of roof trusses and also to protect them from any water damage that might occur.

This easy to use bracket comes in three different sizes so as to cater for new or existing houses and will definitely enhance the lifespan of the branderings.

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