How to replace a rotting porch post

Comstock Images/Comstock/Getty Images

The porch post is a structural necessity that supports the roof of a porch. While damage from wood rot is usually confined to a few inches near the bottom of the post, some older houses can suffer more serious rot problems.

If left unchecked, rot can spread through the entire post, resulting in the potential collapse of the porch’s roof.

Measure the length of the porch post. Subtract the height of the unextended jack from this measurement. Cut a piece of 2-by-4-inch timber to the resulting figure.

Place the piece of timber vertically on top of the jack near the porch post. Jack the timber up so that it is solidly wedged. This will support the porch while work is being carried out on the rotten post.

Identify the rotten parts of the porch post. Drill exploratory holes into the rotted sections to assess how far the rot has penetrated. Shallow rot that hasn’t reached the centre of the post can be remedied with wood filler.

Mark sections which have rotted through. Use a spirit level to make horizontal cutting guides around the post. Cut the rotten sections out using a saw and make sure to keep cuts square.

Measure the dimensions of the removed section and buy replacement wood that is cut to these measurements. Match the type of wood if possible – local timber merchants will be able to advise on wood types.

Check that the replacement section fits in the gap and is flush on all sides. When satisfied, apply expoxy adhesive to the top and bottom of the replacement section and inset it into the gap. Hold it in place until the expoxy has dried.

Prime the newly inserted section. Then paint the entire post – simply painting the new addition will draw attention to it. When the paint is dry, lower the jack and remove the support post.