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Repair A Rotted Porch Column

Repair A Rotted Porch Column

Structural Porch Column Rot Repair

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

Columns add charm, personality and beauty to walkways, decks, landings and porches. Many of the homes where I live have beautifully turned wood posts as structural posts for porches.

Unfortunately because the posts are situated along the exterior perimeter of the porch they get wet by wind driven rain and roof run off or splash up, resulting in rot at the base. Porch column rot is pretty common along the base and eventually become a home for carpenter ants.

Carpenter Ants and Wood Rot

Ants are interesting creatures. Did you know that an ant can carry 50 times its body weight? If that’s the case why repair the column . . . just kidding.

Accepting that ants live in nature is one thing but having them live in your home is another. No matter how you feel on this topic I’m sure you prefer not to have an ant problem in your home or living in your porch posts.

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 think about the fact that there are 1.5 million ants on the planet for every person then it’s easier 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.

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.

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

Jacking and Temporary Supports:

I often use 2×6 lumber as temporary porch post supports. I make “T-shaped” jacking or shoring post. The “T” shape keeps the two boards rigid, preventing each board from bending on their flats. I install 3-inch nails every 12-inches to secure the two boards together.

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

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″ with two 3-inch 12d nails.

Dutchman patch – done in place

Assessing 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 store bought, replacement posts looked vastly different. They were close in looks, but not close enough to pass muster. The option to repair this post became a better option.

We assessed the post and determined that if we cut higher than the rot, in the middle, we would create a “stepped – key” effect essentially making our post repair a stronger connection and also avoid creating a “hinge” point at the repair.

Removing the Column:

Using a reciprocating saw and multi-tool we cut out all of the nails fastened through the post at the top post, bottom post, and railing connections. The next step is to remove the porch column rot and that is when the ants came scurrying out!

Cutting Out the Rot:

We used a circular saw to make all of the long cuts and finished them and all cross cuts with a multi-tool. By making these cuts on a work bench, result in better working conditions which usually mean better looking cuts and results.

Replacement Material:

I like to use mahogany or cedar for my rot replacement material; you see cedar in these pictures.

We rough-sized our stock on the table saw, leaving it long, and glued it together with epoxy and clamps. We allowed it to dry overnight and the next morning we used a thickness planer thin down the glue-up to achieve a fit snug in our middle section cut-out. We dry fitted the repair and then glued and clamped the middle repair into the post.
When dry we glued and clamped the two outer sections and allowed to dry overnight.

Two-Part Epoxy:

In situations like this we like to use a product called West System epoxy to bond the repair materials. This epoxy is a versatile, 2-part, marine-grade epoxy that bonds and coats fiberglass, wood, metal, fabrics and other composite materials to provide superior strength and moisture resistance.

Two-step bonding, or structural adhesion, is the preferred method for most situations because it promotes maximum epoxy penetration into the bonding surface and prevents resin-starved joints. We work the epoxy into the wood surfaces with a throw away bristle brush.

NOTE – Before mixing epoxy, check all parts to be bonded for proper fit and surface preparation, gather all the clamps and tools necessary for the operation.

Epoxy Bonding Steps:

Make sure to follow manufacturers recommendations.

Wet-out bonding surfaces-Apply a neat resin/hardener mixture (without fillers) to the surfaces to be joined. Wet out small or tight areas with a disposable brush.

Apply thickened epoxy to one bonding surface.   Apply enough of the mixture to one of the surfaces, so that a small amount will squeeze out when the surfaces are joined together with a force equivalent to a firm hand grip.

Clamp components and sse just enough clamping pressure to squeeze a small amount of the epoxy from the joint, indicating  good contact with both mating surfaces .

Remove or shape excess adhesive that squeezes out of the joint as soon as the joint is secured with clamps.


Once epoxy applied and the repair is inserted into the post cut out we applied bar clamps and allowed the repair to sit overnight.

Sizing Post Glue Up:

The next morning we used a power planer to take down the high spots on the Cedar glue-up and a belt sander to fine tune the repair. Once the repair and post were at the same plane, and smooth we cut the post to size. The repair and post are then finish sanded with an orbital sander and 120-grit, and primed all edges as well especially the end grain.

Back at the porch we traced the post base out on the mahogany decking and used a multi tool to cutout the decking. We then filled this cut out area with a pvc shim patch. We do this so the new structural post will not sit on top of the decking, causing problems later when deck boards need to be replaced. The pvc is planed to sit just below the deck surface and hides the post seam – nice look!

Installation of Repaired Post:

The post is then positioned back in place, plumbed and we countersink screws into the base and top of post. Later we cover these screw locations with wood plugs or epoxy filler or wood-filler.

With the post plumb and fastened to the header, deck and railing we then remove the temporary support post and slowly lower the hydraulic jack.

Two coats of quality paint finish the repair.



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