Your porch railing is the first thing that people see when they approach your home. It gives a first impression that lasts so keeping it in good condition is important. A rotting porch railing is also a safety concern. Time and moisture can cause the wood railings and posts to rot, making it important to check the railings regularly. It is not hard to repair small rotting sections of the railing with only a few tools.
This method of repair can be used on any wood railings, and also for rotting window and door frames but not for load-bearing structures.
Step 1 - Remove the Rotten Board
Remove the board and examine the extent of the rot. If the rot is extensive and involves the whole railing, you will need to replace the whole rail, but if it is just the end or a small area is affected this method will work for you. Remove any loose rotted wood that is crumbly or very soft. You can use a screwdriver or wire brush for this job. You need to get back to reasonably firm and good wood. Then allow it to dry completely.
Step 2 - Drill Holes in the Board
The wood must be thoroughly dry before going any further. Using a ¼-inch bit, drill holes into the wood around the rotten part, taking care not to drill right through.
Step 3 - Coat with Wood Hardener
Coat the surrounding area and into the holes with the wood hardener. Lather on a few coats, taking care to get into every hole and crevice. Let it dry for at least three hours. The wood hardener penetrates the softwood and makes it stable and hard again.
Step 4 - Screw in Some Long Screws
If the rot has been extensive, screw some long screws into the rotten bit (these will be covered over later), make sure they do not poke out from the general shape of the board. They reinforce and strengthen the filler.
Step 5 - Mix up Wood Filler
Mix up some wood filler according to the directions. Don't use auto body filler as it will not expand and contract with the wood in differing weather conditions. Fill the hole with the filler making sure to work it into all the holes. Build it up in layers no thicker than ½ inch until the whole rotted hole is filled. Wood filler sets quickly so work with small batches at a time before making up more. Let it cure for at least 30 minutes after you are done.
Step 6 - Sand the Rail
Using the sander, sand the piece until the rail looks the same as it did originally. This will not take long and if you take some care, the finished rail will look as good as new after painting.
Step 7 - Prime and Paint the Rail
Prime and paint the rail to match the rest and replace it into the porch railing.