Dry rot affects many wood pieces both indoors and outdoors. While dry rot is bad for the wood and weakens it, if caught in time, the rotten wood can be replaced with an epoxy filler. The filler helps prevent further damage from wet or dry rot and returns the wood to its former functionality.
Proper preparation is the best way to prevent further damage from occurring to the wood. Make sure that the moisture that caused the rot is completely eliminated. If more than 60 percent of the wood is rotten, then you will have to replace the whole wood rather than fix it with epoxy. Remove the rotten wood with a chisel. Once this is done, you can clean the remaining wood with a clean, damp cloth to eliminate any dust or dirt from the area.
The wood should be injected with a borate preservative to stop the wood from rotting any more. Drill holes 1/4 inch deep every 6 inches along the remaining wood. Inject the borate solution into the holes until the solution starts to leak out from the holes. Apply an epoxy primer over the whole exposed wood area with a disposable paintbrush. Allow the solution to dry for two to four hours before applying the epoxy filler.
Epoxy filler comes in two separate solutions that, when mixed, harden to a consistency that is as hard as wood itself. Mix the two solutions together on a piece of cardboard. You will have to mix the solutions together for about two to three minutes to ensure they are completely mixed. If this is not done, then the epoxy may not dry properly. Apply the epoxy over the exposed wood using a putty knife. Smooth the epoxy as much as possible with the putty knife. If further shaping is needed, you can wear some rubber gloves and shape the epoxy with your fingers. If the epoxy sticks to your gloves, you can wet them with water or the epoxy primer. This will prevent the epoxy from sticking to the gloves.
When the epoxy has dried (around 24 hours), use sandpaper to smooth the epoxy and blend it into the surrounding wood. Use a fine-grit sandpaper; larger grits will gouge and damage the epoxy coating. Clean the dust away with a damp rag. Paint over the epoxy and wood. The piece will now look as good as new.