How to Replace a Deck Post | This Old House

Shoring up an old deck with new supports with This Old House general contractor Tom Silva. (See below for a shopping list and tools.)

Tom Silva and Kevin O'Connor replaced several wooden 4x4 posts that were supporting an exterior deck. The posts, which were not pressure-treated, sat directly on top of concrete piers. They had completely rotted at the bottom due to moisture wicking up through the concrete. Before removing the old posts, Tom & Kevin installed temporary bracing using 2x4's and a sledge hammer. With the deck temporarily supported, they removed the old posts and installed new pressure-treated ones. They also installed a galvanized steel post base at the bottom of each post, eliminating direct contact with the concrete piers.

Shopping List for for Replacing a Deck Post:
- 2x4s, for making temporary posts
- pressure-treated 4x4s, used as posts
- pressure-treated 2x4s, to make diagonal braces
- metal post base and expansion anchor, used to secure the post to the pier
- 3-inch decking screws, used to attach diagonal bracing

Tools for Replacing a Deck Post:
- hammer
- reciprocating saw
- pry bar, for pulling nails
- hammer drill fitted with 1/2-inch-diameter masonry bit, used to bore anchor holes in concrete piers
- impact wrench, for tightening expansion anchors
- miter saw
- small sledgehammer
- impact driver

Resources:
Pressure-treated 4x4 posts are available in home centers and professional lumberyards.

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How to Replace a Deck Post | This Old House

[gameragedad]

I love YouTube for reasons like this. Thanks for passing this kind of knowledge down through the generations!

[Juniordc]

I️ can’t thank this organization “This Old House” enough. This channel has influenced my career path!

[FernandoRodriguez-dsri]

I always come to this channel when I’m face to face with a new project. Always seems to help.


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[rwg]

Tommy Silva You Do Great Work Buddy...

[MRrwmac]

Like to see Kevin finally working after soooo many years of watching. Thanks for showing us how it's done and done correctly!

[dannyellis]

Those guys are really good at there work, great job 👍

[themalacast]

I’d be nervous to drive a screw while Tommy’s intently watching lol

[dirediredude]

Awesome stuff. Any idea what something like this would cost if you had it done by a contractor? I'm looking to do something similar with my deck. Would also want to add cement bases like theyve got here too.

[Chuckish]

At least they caught it before it was beyond repair and had to be taken down.

[Blobjonblob]

Kevin is getting fairly handy with the odd tools

[BrentLagerman]

wish you guys were up in the hudson valley to help me fix my porch!

[faw]

Suggest use stainless steel wedge anchors to avoid rust.

[ionlyplayps]

Man, I wish I knew, what tommy a good handyman

[jeffreychan]

Why am I watching this? I don't even have a deck. *Cries in poor*

[CarolynL.Vachon]

I have a question on the side of your deck, that you have a big sheet of it on the side of your deck. Sorry, I don't know what it is called. I had an animal brake my. My husband and I don't know how to fix it. We have ideas, nut sure. Ty if I hear from you

[billshadel]

What if the beam wasn't straight (if it was sagging below the 16" measurement)? I wish they could have discussed that possibility. I have a deck that sits only 18" off the ground that is sagging in a corner because of a rotted post.

[itsmeforsure]

I'm not a builder but when he used 2- 2x4's to hold up a deck that was being held up by 3 4x4's, that seemed alittle shakey.

[dennisj.varadesr]

35 years ago! I installed 4x4 fence posts. I put up stockade fencing, I replaced the fencing twice over the years. When I originally installed the 4x4's I did not use concrete. Because of the costly experience, I had in a previous home where the posts heaved in 1 year, not to mention that the wood rotted quickly (Good treated ground contact 4x4s). Well 35 years, I only replaced 2 posts the rest did not rot! My neighbor hired a contractor 6 years ago to install their fence. I told the contractor when he was using concrete that the fence would fail. He and his crew looked at me like I was nuts, laughed at me and told me that whatever the big box store recommends is how things are built. Well, the fence failed! The problem is the concrete, don't use it to support anything you are going to build on top. Use wood posts as deep as you can get them, wrap near the top with styrofoam. Mistakes are costly, and concrete is a big one.

[Jesse-gvtf]

Why isn't that wedge anchor not hot dipped galvanized? Is that zinc plated anchor good enough for outdoor applications?

[stevenquinones]

Would this be the same process for posts that are buried under the ground? I want to apply the cement method for my deck but not sure how to pull the existing post from under the ground.