How to Repair a Rotted Porch Post | Ask This Old House

Ask This Old House general contractor Tom Silva shows how to permanently patch a decaying porch post. (See below for a shopping list, tools, and steps.)

Shopping List for How to Repair a Rotted Porch Post:

Tools List for How to Repair a Rotted Porch Post:

Steps for How to Repair a Rotted Porch Post:
1. Unscrew and remove the handrail attached to the rotted porch post.
2. Temporarily support the porch roof on either side of the rotted post with a hydraulic jack and a long 2x4 post.
3. Use a reciprocating saw to cut the top of the post free from the overhead beam.
4. Remove the rotted post and lay it across two sawhorses.
5. Cut away the rotted section from the bottom end of the post using a circular saw.
6. Cut a new post section from a rough-sawn cedar 6x6.
7. Mark and cut a half-lap scarf joint into the new post section using a circular saw and reciprocating saw.
8. Set the new post section on top of the old post and trace the half-lap scarf joint onto the old post.
9. Cut a mating scarf joint into the old post.
10. Sand the joint smooth with a random-orbit sander, then fine-tune the joint with a hammer and chisel.
11. Apply several beads of construction adhesive to the scarf joint cut into the post.
12. Evenly spread the adhesive over the entire joint with a flexible-blade putty knife.
13. Fasten the new post to the old post with four 5-inch-long structural screws. Use an impact driver to drive the screwheads about 1/4 inch below the surface.
14. Use a power plane to trim the new post section flush with the old post.
15. Fill all screw holes and cracks with exterior-grade wood putty.
16. Once the putty dries, sand the post smooth.
17. Coat all bare wood surfaces with exterior-grade spray primer.
18. Screw the base plate to the bottom of the post.
19. Stand the repaired post back in place on the porch, then release the hydraulic jacks and remove the temporary 2x4 posts.
20. Secure the top and bottom of the post with screws, then apply a paint top coat to the post.
21. Reattach the handrail to the post.

About Ask This Old House TV:
Homeowners have a virtual truckload of questions for us on smaller projects, and we're ready to answer. Ask This Old House solves the steady stream of home improvement problems faced by our viewers—and we make house calls! Ask This Old House features some familiar faces from This Old House, including Kevin O'Connor, general contractor Tom Silva, plumbing and heating expert Richard Trethewey, and landscape contractor Roger Cook.

Follow This Old House and Ask This Old House:

How to Repair a Rotted Porch Post | Ask This Old House

[aixpert]

Wow. Cutting it at those angles was really clever! I wouldn't have thought of that. You are truly an artist.

[bornfree]

I am a carpenter over 30 yrs, yet i always learn something new when i watch this old house, thank's guy's.

[BrocAndAimee]

I love that there isn’t high production to these videos, just good information and hard work

[mjpatel]

i have no porch
i have no post
but don't know why i am watching this video
but honestly after watching it i fill relaxing!

[xcottcraver]

I followed these directions to repair a solid cedar porch post, and it came out perfect. I made up for my lack of skill with (1) careful planning and measuring, (2) milling the bottom weeks before disassembling anything, (3) milling a second bottom for practice and to gauge their fit, and (4) clamping angle aluminum guides to the post to limit my hand saw. Probably dulled the hand saw, but I'll sacrifice a handsaw for a working porch. Saved me huge money, and now I know how to do it again if another post needs it. Thanks TOH for brilliant and practical advice.

[theHAL]

Tom is the man. Getting those nice scarf joints with a skilsaw and a reciprocating saw is pretty slick.

[dannyash]

It's very tough to make those precision cuts with a Sawzall. He doesn't even break a sweat.

[lilianabellini]

There is something about a well trained and knowledgeable construction projects done right the first time, you can’t get better than Tommy Silva. Thank you

[mountainwolf]

I really don't mean to sound funny but I love you guys. You guys have taught me so much since I was a teenager God bless you for sharing your gifts.

[brocksargeant]

This is tremendously helpful...my problem is the rotting posts I have are 25- foot-tall columns, so everything is about twice the size.

[MyGloriousMess]

Wow! Skill and artistry at its best. Nice work Tommy!

[rod]

This is exactly the video I was looking for to fix a few wood rot posts on an old porch. Great work and as a hobby wood worker I appreciate the joinery method used.

[ImDanimal]

Probably the best TOH video... I have watched it so many times... Tommy a true craftsman.

[brianclark]

Awesome job !
Great idea and trick to salvage that post !
Thank you Tom and this old house!

[CADstruction]

Tommy reminds me of my old design technology teacher. Old school carpentry.

[zxrdood]

"Well that's the eyedear"
-Tom Silva

[Lolaismypoopydog]

I’m glad that the homeowner was there to hold the post

[jjf]

A true expert craftsman. Thank for this video. Can't believe anyone would give it a "dislike"?

[HTHAMMACK]

Tom Silva, you are a beauty. We need more skilled tradesmen like you in the world.

[Engineer]

Such a job takes a lot of courage and skill. Failure is no option when you start on this. Also funny how he jacked the whole roof up lol. Where i live all houses are bricks and concrete.. If you jacked a roof up like that you would demolish the whole house.