Deck Post Rot Repair: How to Spot and Fix Rotten Deck Posts
By STOP THE ROT CO.
Deck posts do two jobs. The structural posts carry the deck, and the railing posts keep people from falling off it. Either kind can rot, and it almost always starts where you cannot see it.
Why the base of the post rots first
The cut end of a post is end grain, and end grain soaks up water like a straw. Water collects where the post meets the deck surface, a concrete footing or a metal bracket, and it stays there. Add Vancouver’s wet season and the base of the post can be soft while the top looks perfect.
A post that sits directly on concrete or in the ground is at the highest risk. A post lifted off the surface on a metal standoff base dries out between rains.
How to test a post
- Look at the base. Dark staining, cracks, or paint that is lifting.
- Press a screwdriver into the base and the lower 30 cm. If it sinks in easily, the wood is rotten.
- Check for movement. Push on the post. A railing post that wobbles is not safe, even if you can only feel it at the base.
- Look at the connections. Rust on bolts and brackets is a sign that water is getting in.
If a railing post is loose, keep people away from that section until it is checked.
Repair or replace?
- Repair works when the rot is shallow and contained. The soft wood is cut out, the area is consolidated and filled, and the post is sealed.
- Replace is the honest answer when the rot is deep, when the post has lost strength, or when it is a structural post under the deck. The beam above is supported while the post is swapped.
- Rebuild the base detail. A new post set directly on wet concrete will rot again. Lifting it on a standoff base and sealing the end grain is what makes the repair last.
Look at the cause too
Rot in a post usually comes with a water problem: a deck that drains toward the post, missing flashing, a ledger leak or a gap that holds water. Fixing the post without fixing the cause is why many repairs fail within a few years.
What it costs
Rebuilding an entrance post is typically about $1,750 to $2,800+ in Canadian dollars. Other deck posts are priced after a free inspection because the cost depends on the post, the height and what supports it. That is a starting range, not a quote. You get a written quote about 15 minutes after we finish.
Next step
Not sure if a post is rotten? Send us a photo and we call or text you within 15 minutes. You can also read about deck repair, deck railing, porch and post repair and what wood rot repair costs, or book the free 20-point inspection. Every repair has a 2-year craftsmanship guarantee.
