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Structural Porch Column Rot Repair

Construction How-To, Outdoor Living, Porches and Gazebos May 26, 2015 Sonia


What do anthills and porch columns have in common? The answer should be nothing, but we know better…

By Rob Robillard

 

 

 

 

 

 

Columns add charm, personality and beauty to walkways, decks, landings and porches.  Many of the homes where I live have beautifully turned wood columns as structural posts for porches. Unfortunately, because the posts are situated along the exterior perimeter of the porch, the wood is exposed to wind-driven rain and roof runoff or splash-up, resulting in rot at the base. Porch column rot is pretty common along the base and eventually becomes a home for carpenter ants.

As a renovation contractor I see carpenter ants in just about every home I work on, mostly around damp wood as a result of water intrusion or lack of proper maintenance. When you consider that there are 1.5 million ants on the planet for every person, it’s easy to understand why I see so many ants.

If you have a rotted structural porch post, you can either replace the column or repair it; on this project, we chose the latter.

Support All Structural Repairs

When a column supports a roof or structure it is considered structural. Prior to replacement or major repair you should take steps to temporary provide structural support to the area around the post needing repairs or replacement.

Although some minor repairs for porch column rot can be done in place, when the rot is extensive enough, the best way to perform these repairs is on a workbench.

I often use 2×6 lumber as temporary porch post supports.

A T-shaped shoring post is used in conjunction with a hydraulic jack to lift the overhead structure.

A T-shaped shoring post is used in conjunction with a hydraulic jack to lift the overhead structure.

I make a “T-shaped” jacking or shoring post. The “T”, formed from two board, keeps the support surface rigid, preventing each board from bending on their flats. I install 3-in. nails every 12 inches to secure the two boards together.

Protect the overhead structure with blocking to distribute the pressure.

Protect the overhead structure with blocking to distribute the pressure.

I use a small 10-ton hydraulic jack to raise the shoring post and overhead structure approximately 1/8 inch. This assists in getting a reciprocating blade to cut the fasteners away and remove the post. It also assists later when inserting the replacement or repaired post.

Take the weight off the jack with an additional temporary support post (doubled 2x6) then cut loose the post at the top and bottom with a reciprocating saw and remove.

Take the weight off the jack with an additional temporary support post (doubled 2×6) then cut loose the post at the top and bottom with a reciprocating saw and remove.

Once the structure is jacked up, I install a second temporary support post to take the stress off the jack, and to provide additional support at the new height. This second support post can be

T-shaped or simply two 2×6’s doubled together and fastened every 16 inches with two 3-in. 12d nails.

The wood of the post was severely rotted and damaged by ants.

The wood of the post was severely rotted and damaged by ants.

Repairing Rot vs. Replacement

Many times it’s simply easier and less expensive to replace the porch post as opposed to repair it. In our situation we have three identical posts, and the replacement posts at the store looked vastly different—not close enough to pass muster. The decision to repair this post became a better option.

To avoid a weak hinge point where the new wood is spliced into the old, the post was cut above the rot to allow room for an interlocking stepped, keyed joint.

To avoid a weak hinge point where the new wood is spliced into the old, the post was cut above the rot to allow room for an interlocking stepped, keyed joint.