How to fix rotten wood

Repair and consolidate rotten wood

It is not always necessary to completely replace rotten wood. In many cases, the rotten wood can be touched up, repaired and strengthened. Note: If load-bearing wooden parts such as wooden beams are rotten, a structural engineer must always be consulted who will decide on the type of repair. In the following, some methods are described how to repair and stabilize rotten wood.


Repair small damage to rotten wood

If wood is exposed to moisture, sooner or later it will start to rot. This means that the wood loses its strength and tends to break or breakouts occur in the rotten areas. Before starting to repair the rotten wood, the cause of the moisture must be eliminated, otherwise repairs are pointless. When repairing, proceed as follows:

  1. The wooden part must be absolutely dry before you can start repairing the rotten areas. Since rotten wood is brittle, loose pieces of wood should be removed.
  2. Then the holes and cracks are filled. A mixture of window putty and linseed oil can be used to fill the holes. The two components are mixed together in such a way that a paste is created that can be brushed into the holes and cracks with a spatula.
  3. The rotten areas can be repaired more professionally with wood putty or wood filler. The filler is also applied with a spatula. After drying, you can sand these with sandpaper so that a flat surface is created.
  4. The method described above is only suitable for small areas of rot. If the wood parts are more rotten, the wood must be stabilized.


Repair and stabilize rotten wood with epoxy resin

Epoxy resin repair kits for rotten wood are available from specialist retailers. If the putrefaction process has not yet progressed too far, these repair systems can be used to stabilize the rotten wood. The wood fibers are stabilized by the absorbed epoxy resin in such a way that the wooden part regains more strength. However, with this repair method, one cannot expect that the original stability before rotting will be achieved. Therefore, this type of renovation is not suitable for load-bearing wooden structures. The wood renovation with epoxy resin goes as follows:

  1. The epoxy resin repair kits consist of 2 components: the resin and the hardener. These two components are mixed according to the manufacturer's instructions.
  2. Then the epoxy resin is applied to the rotten areas. You can see how the resin is absorbed by the wood fibers. In order to achieve a better suction effect, the epoxy resin can also be diluted with a suitable thinner and thus made more creepable.
  3. In the case of thicker pieces of wood, the epoxy resin can also be drilled into deeper layers. This process can be used to solidify the rotten wood.
  4. If holes and cracks are to be filled, then you can add special fillers to the epoxy resin, which make it tougher so that the resin can be applied with a spatula.
  5. After the epoxy resin has dried, it can be sanded with sandpaper or a rasp.
  6. Since epoxy resin tends to yellow when exposed to UV radiation, it is advisable to paint the treated wood surface with a UV-stable clear varnish.


Repair badly rotten wood

If the putrefaction process is already well advanced, the remediation methods described above will no longer help. Before replacing the entire piece of wood, you should check whether a partial replacement is possible. In the case of load-bearing timber components, a structural engineer must always be called in, who will decide on the type of repair or renovation.

In some cases it is possible to saw out the rotten wooden part and insert the missing part precisely. This type of renovation is often used, especially for antique furniture and historic wooden windows. This type of repair is also used on wooden beams. However, the load-bearing capacity of the wood at the connection point is impaired, so that you should ask a specialist for advice before repairing.

Conclusion: The method of repairing rotten wood depends on the stage of rot and, on the other hand, on the intended use of the wooden component. In the case of wooden parts that have a load-bearing function in a building, an exchange is recommended. For other components such as windows and doors, the wood can either be stabilized with a wooden spatula or epoxy resin. Partial replacement of the rotten wood is also possible.


Categories DIY building materials