conservatory-wooden-frame

Roof Rafter and Joist Replacement

Most of us are aware of the importance of felt, tiles and many exterior roofing materials, but we tend to overlook the vital role rafters and joists play in the structure of our roof. Roof rafters and joists are made up of wood that is nailed, pegged or bolted together to create a structurally interdependent shape that offers great strength. Unfortunately, wood can be prone to water damage, so even a minor leak in your roof can compromise the structural integrity of your joists and rafters over time. Here we’ll explore roof rafter and joist replacement in more detail to help you determine if it is needed for your home.

The Leading Causes of Rafter and Joist Failure

The biggest enemy of any roof structures is water and rafters or joists are no exception. Water leaks can cause penetrating damp even in treated timbers. Even if your rafters and joists have been treated, the wood is unlikely to have been treated the entire way through its thickness. If your rafters sit on or in the walls, they will be even more susceptible to penetrating damp.

Another enemy of rafters and joists is rot or insect attack. These issues are typically associated with damp and can be problematic in older properties where no cavity walls or thick, solid walls support the bearing ends of your rafters. Rot and insects such as woodworm can cause the wood to start to crumble. The initial signs of woodworm are small holes on the surface of the wood, but eventually, the wood dries out, and the nutrients are drained, compromising the structural integrity of the rafter or joist.

Unfortunately, woodworm, or more precisely the adult beetles who spawn the woodworm larvae can migrate between May and October to find a fresh food source and new breeding ground.

Finally, your rafters and joists may be compromised by joint failure. Most modern roof structures use “nail plates,” which are plates fixed with screws, nails, and glue, but older timbers may be connected with wooden pegs or Mortise and Tenon joints, which can be eaten away by insects. This can allow the beams to move, which opens up the joint to further damage.

Replacing Damaged Rafters and Joists

Before any repairs are performed, it is vital that the cause of the damage has been identified and corrected. Since the rafters and joists are bearing the weight of the roof, replacement can be a big job. If a single rafter needs to be replaced, it may be possible for it to be replaced in situ. However, in a worst case scenario, the roof may need to come off to provide suitable access for the removal and replacement.

If you suspect that your rafters or joists have been damaged, you can rely on us. Our recommended experts will examine your rafters and joists to determine if an internal removal and replacement is possible or if you will need more extensive work and discuss all the options with you, so you can make an informed decision.