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.)
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Tom used a half-lap joint to attach the new post to the old post. He then used "Ready Patch" exterior spackle to fill the small gaps. It is manufactured by Rust-oleum [www.rustoleum....].
Shopping List for How to Repair a Rotted Porch Post:
2x4s [amzn.to/2Lwm9DJ], used as temporary support posts
Two sawhorses [amzn.to/2LoRI3Q]
Rough-sawn cedar 6x6 [amzn.to/2MWKYfk], to patch rotted post
100-grit abrasive disks [amzn.to/2ZM0exz], for random-orbit sander
Construction adhesive [amzn.to/2HPObsZ], for adhering the new post section
5-inch structural screws [amzn.to/2MWXo74], to secure the new post section
Exterior-grade wood putty [amzn.to/2LjUoiW], for filling holes and cracks
Spray primer [amzn.to/2LlENiP] and paint top coat [amzn.to/2MVpsb1]
Tools List for How to Repair a Rotted Porch Post:
Cordless impact driver [amzn.to/2LraKFj]
Hydraulic jacks [amzn.to/2NQp1OM], to temporarily support the porch roof
Reciprocating saw [amzn.to/2NQJfI5]
Circular saw [amzn.to/2zWYuY0]
Layout square [amzn.to/2UuozXK], for marking scarf joint cutlines
Random-orbit sander [amzn.to/2ZQYjb8]
Hammer [amzn.to/2UuaXvL] and wood chisel [amzn.to/2PNvVqI], for cleaning up scarf joint
Caulk gun [amzn.to/2UtWobu], for applying construction adhesive
Putty knife [amzn.to/2NYqiDg], for spreading construction adhesive
Power plane [amzn.to/2NQ9C0L], to plane down the new post section
3-inch sash paintbrush [amzn.to/2ZM27KR], for applying paint
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.
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How to Repair a Rotted Porch Post | Ask This Old House
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[@aixpert291]

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

[@recless8667]

Scott_T you should look into the term "end joinery" then, it's typical carpentry work for real craftsmen that do more than just make plywood cabinets

[@JaredCzaia]

The Japanese are the masters of scarf joinery. So many different scarves for so many different occasions. Mostly horizontal and vertical though.

[@moondawg3693]

@@JaredCzaia Ship builders the world over were and still are the masters of scarf joints and everything else wood, not only the Japanese.

[@kalijasin]

scarf + half-lap

[@CheeseBae]

That's far older than Tom. They've been doing timber frame joinery that way for hundreds if not thousands of years.

[@bornfree3124]

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

[@mjpatel20003]

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!

[@progamerxdprogamer4350]

M J same

[@thelazykilla5991]

Same

[@elliedefox2783]

Same

[@jdsheleg8332]

Most of the time I just dream about doing things like this, they are so satisfying once accomplished. In the meantime, I have to expend my days running around delivering mail.

[@mammothfilms]

Josue Nieves I’d enjoy delivering mail more than my current profession. The grass is always greener....

[@theHAL9000]

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

[@xcottcraver438]

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.

[@dannyash3805]

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

[@steakwilliams4448]

@John Michael that makes sense. I was wondering how he got that clean cut

[@hoodhomesgardens]

Lol. You never seen me use a sawzall.:P.

[@SmartestGeneration]

Yeah hence why hes rocking festool cordless this guys got a reputation and I would love to be his apprentice

[@2tallandcute4u]

Yeah, I need to do this with only a circular saw.....HELP!!!!!!!!......LOL

[@niallmcgeehan6222]

It wil be about 11..30

[@lilianabellini7895]

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

[@BigDsHomestead]

You put him and Norm Abrams together and I bet they could build you a mansion. I wish I had their help around my place. I haven't been able to get anything done do to my multiple surgeries. I really love carpentry, too.

[@mountainwolf1]

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.

[@edball4906]

IREALLYDON'TMEANTOFUNNYBUTLOVEYOUGUYSYOUGUYSBABYTAUGHTMESO

[@MyGloriousMess]

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

[@Lolaismypoopydog2036]

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

[@ImDanimal85]

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

[@HTHAMMACK1]

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

[@rod1951]

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.

[@santaclaus179]

all these old houses are so beautiful , and still standing

[@zx6rdood]

"Well that's the eyedear" -Tom Silva

[@brianclark2876]

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.

[@jjf609]

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

[@brocksargeant1134]

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

[@caseyreppas3913]

Thanks for this how to video bob.. I have a 2 story balcony on my 1865 home I have to replace the rotted post on.. so this weekend when it stops raining, I'm going to start with the bottle Jack's the 4x6x12 post, and hope I can repair and replace the rotted wood without any problem. IM SECURING IT WITH 6 DOUBBLED 2X4S CUT THE SAME WAY BEFORE REMOVING THE ROTTED POST.. THANKS FOR SHOWING ME HOW TO DO THIS. WISH ME LUCK. IVE NEVER DONE THIS BEFORE. ❤

[@caseyreppas3913]

Mine is 80 ft. Up and is a 2 story balcony did it work for you?

[@caseyreppas3913]

If so, how many 4x6 pressure treated pieces did you use to secure it ? Before removing the post?

[@ShakespeareCafe]

TOH saves the day. That angle cut was genius, but that's Tommy

[@azizmomand7163]

God bless Tom silver and all the Ask This Old House crew . I learned a lot from you .

[@traviswillis8308]

Tommy is a natural, he really puts his heart and soul into anything he does. I don’t think there’s anything he can’t do

[@chrismoody1342]

Ole Tommy, he’s seen it all and done it all.

[@Engineer9736]

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.

[@meo1960]

I'm definitely gonna steal that idea Tom. Thanks for the GREAT TIP.

[@lennythomas7230]

I tell you what I don't care what Tom does he always knocks it out of the park!

[@shaidyn8278]

Having watched his video regarding the speed square, it was great to see it in action.

[@solidsnayyke1914]

I dont even own a house and I love watching this guy.

[@rawbacon]

I see several comments saying he made those cuts with the Sawzall. He just used the Sawzall to cut out the middle because the circular saw couldn't make deep enough cuts.

[@paultrigger3798]

precision cuts with a reciprocating saw like a boss

[@davidstajic]

Big respect from Germany !

[@Pro1er]

Watching these videos really inspires me to... watch more videos and drink my coffee.

[@kalijasin]

Amazing Fix Tom Silva. Great job.

[@ytrbro1041]

by the angle of the wood on both sides, when the weight comes down it forces both of the woods together, experienced woodsman technique, really cool to hear? "good for another 100 years" 👍🤓♥

[@jr.8509]

This is one of my Summer projects... Tommy Rocks!!!!

[@masterofmasterofr123]

So glad I found your video as I have the exact same issue with 2 of my verandah posts. I'm curious as to why you didn't prime the underneath of the base plate though.

[@timf5963]

I'll be doing this at my mom's house in the spring. Definitely will be referring to this. I only hope I can make as accurate cuts with my reciprocating saw!

[@quranquran1032]

Thank you tommy Nice to see you at work

[@Lee-xw9fr]

Great video, would love to see how you would tackle a cylindrical post with the same issue.

[@greenimpala8147]

he really is good, love the joint he made

[@mae2759]

He does such a great job on that... I can't get over it. Like where do you find a rought sawn 6x6 to do the job right? Great job!

[@user-to2qk9oz6b]

Wow this the cleanest work I have seen

[@lees5097]

Tom Silva, the Master.

[@danielg.1365]

I love this you tube channel, I could watch these videos all day long!

[@dennystrate9849]

He always has a great ideaer not even a word

[@ThePRESTIGE34]

Tommy never ceases to amaze

[@no_handle_required]

he makes it look so easy and i'm like, yea, I'm going to lowes and buying a new post.

[@samfdsd2134]

the joint part is so clever!

[@oldskoolwayy]

This is the benefit of having old school carpenters still around they have really seen and done it all..A new school carpenter would have never thought to cut it at an miter...lol..

[@TheFoldMusic]

Such strong work!

[@BrianHornak]

He makes it look much easier than it might actually be....

[@timmartin3927]

The only thing he did wrong is nothing. I never get tired of watching This Old House.

[@RoselineRabouin]

This is nice I need something like that.

[@marke8930]

Tom Silva is a wizard

[@larrymoore6640]

Another lesson learned from Tommy. I have a question, how was the bottom of the post fastened to the porch??

[@joncor1]

I am running into the same problem, great video. I am going to try and duplicate that angle cut. I hope this will work on my wood posts which I just realized are hollow. Thanks

[@vikingcove]

With hollow post you can insert a filler core to add strength.

[@Karrde]

I looks perfectly done... but when he said he couldn't see where the old patch was he was lying through his nose. :p

[@a0flj0]

Idunno, the quality of the video isn't good enough to be able to tell for sure. But after two or three layers of oil paint, given that he filled all gaps, it would absolutely be possible that the joint is not visible at all. I use the same finishing technique on edge-glued boards, and you never can tell where the joints are, after painting.

[@MatanuskaHIGH]

+Florin Jurcovici i clearly see the joint on my tablet screen

[@EricInTampaAcoustic]

+matanuska high excellent execution but he probably either did not see that joint or did not care ..lol

[@godbluffvdgg]

If you're in the trades or have a good knowledge of wood, you'll always see a seam like that...No biggie, beats the shit out of that ugly rot! :) If I'm doing that job and someone complained about that seam, I would fix it with my chainsaw...:)

[@EricInTampaAcoustic]

+godbluffvdgg ,haha, no doubt bro

[@aidanray4846]

Wow. You’ve got some great carpentry skills. Good job. That’s coming from an electrician

[@suchasnidvongs]

The craftsmanship looks great.However, I would have done one thing to ensure the longevity of the project: Prime the bottom of the base and ad nd deck wood and set it in high quality adhesive sealant before dropping the weight on the post. The pressure will squeeze the sealant out and keep water from seeping into the space between the deck floor and the base through capillary action.

[@Perly53]

I'm repairing my porch posts that are hollow 4 x 4's with rotted bottoms. The hard part is not having all of the portable tools that Tommy uses, such as the planer, orbital sander, and reciprocating saw. I tried using my multi-tool with both a metal blade and a nails-in-wood blade, but they didn't even cut through a single screw before being dull and useless. My first one is cut, screwed, and glued. It's going to dry overnight. I need those tools I mentioned though to do a clean job.

[@gr1nder07]

No one gets all those tools at once, you build them up little by little over time. Buy the tools that are useful for the most projects first and start obtaining the lesser used/specialty tools as your able.

[@bg147]

Nicely done. I would replace that plastic hand rail.

[@giotinez5996]

You are a legend sir what a perfect job.

[@spetruck1]

That cut was awesome

[@matchbox3eb]

That was some impressive work. Hats off for sure

[@USCGJJ]

I love the video man, perfect cuts.

[@StreetKingz4Life]

but i saw where the old patch was...

[@yaosio]

They just have to sand down the seam from the spackle and paint over it again.

[@XZaapryca]

What Cat Man said. They only put a thin coat of primer on, not finish paint. You wouldn't paint it before install, what if you had butter fingers and scratched it? :)

[@tckearns8468]

Excellent video. My question is what direction the scarf cut should face when I replace the repaired porch post? I read from another online forum that "the plane of scarf should be perpendicular to the deck ledger or deck beam".

[@aarondelaughter1658]

Excellent work

[@jorge31415927]

That was a tremendous fix!

[@rupe53]

The only thing I would have done different would be to test fit that railing before setting the weight on the post. No sense is having to force it into place or wind up with a small gap. Might as well secure the railing too, then set the weight down before throwing a few screws into the bottom. As for seeing the slight lump of adhesive at the joint, that can be fine tuned in a few days when it's fully cured and then sanded down before finish paint goes on.

[@zomgosz1503]

Wow! Great work and great idea to cut an an angle!

[@bradbarber799]

love the angle cuts

[@chrissiebronx9662]

I love this old house

[@llNATEDOGGll]

Tommy knows his shit.. Would love for all the crew to build my house.

[@radchander]

I really want to know if there is anything this guy can’t fix….great work, especially the scarf joint 🙏

[@RealGame101]

thank goodness for videos like this?

[@MrCstevens73]

Not messing around. Way to go, Tommy. #Mastery

[@Troy-Echo]

Great example of how to shift support from the column to temporary supports. Those angle cuts were the perfect trick! Although you can see the patch work easily. The part you can see easily is where the angle of the cut was ever so slightly off and the weight on the column is pushing that little section. Considering he did these cuts by hand, that's pretty freaking close to perfect in my book! A quick hit with the sander would blend that in great in

[@tonym6920]

I have columns similar to that on my 16 year old ranch and one of them is already showing rot on the bottom. I’ve patched it temporarily. There are three columns in total so I’m guessing the other two can’t be far behind. I’m planning on replacing them but I do have one question. These columns are hollow, should I ventilate them by Installing a vent at the top of the column? The bottom of the column sits on a base that keeps it off the concrete and doesn’t block the hole in the column. I’ve read that installing a vent at the top allows for proper ventilation. What’s your opinion.

[@arth.4196]

Great Job Tommy 👏 👍

[@jsneds347]

I really love these videos and you make it look easy. Is there a video on replacing T1-11 siding? The siding on my house is rotting and I want to replace it the same time I replace the windows. Thank you

[@rtang10005]

Great video. Thank you!

[@rbrown2925]

Love the angled column joint but good luck with the cedar depending on the environment. I’ve got a lot of western red on a deck that rotted out in 10 years.

[@jamesmcnaughton5092]

Interesting,I thought ceder was a very rot resistant wood 🤔

[@rbrown2925]

@@jamesmcnaughton5092 Me, too, but I’ve been told that cedar’s good reputation was based on the wood from old forest trees. The wood from much newer reforested trees is nowhere near as rot resistant. Maybe it’s BS but I’m inclined to believe it based on my experience. Maybe a forestry/wood expert could set the record straight with some real science???

[@strokerace4765]

I worked on a horse barn once and the lead guy cut the 6x6 pt post a little short, instead of buying another $60 6x6 we drilled three holes in the end and inserted rebar then hammered on a foot long 6x6 piece. I hope no one goes cutting into it one day.

[@SaucySharp]

What about my hand rail Tommy? Figure it out.

[@milonkill]

😂😂😂

[@pattieboon7322]

Wow! I need this wonderful man to fix my Lytchgate, same problem. May have to have it removed though, otherwise, it's going to be a costly job.

[@jeffs-zw2zb]

I wish i had 1/1000 nth of this guys knowledge. I'd be set.

[@RoastBeefSandwich]

7:15 Can't see the line can ya Russ?

[@charliecharlie9377]

Nope Dad, I can't. 0__0

[@EugenioFranklin]

That is so easy to fix. The hardest stuff was done right.

[@kjageld]

What angle are you using to cut the two parallels ???

[@maryperz-jones4528]

I asked the same thing, it appears to be 23 degrees

[@rickjohnson1632]

You rock Tommy 👍

[@hj8607]

How about a series strictly about house demolition called " Axe This Old House ?"

[@jingyak7]

Artist here! Best work of all time! How far you are from 91941?

[@vicentegarcia3114]

Can't get better than that!

[@annikagroebner7534]

Beautiful Work...

[@amilcarduglasbenites583]

me gustan mucho sus videos. bendiciones

[@keehn20]

That’s a gosh dang good idea.

[@glorygloryhallelujah]

Interesting that he used a sidewinder to cut the lumber then used a worm drive to mill it.

[@lucywang1339]

Thanks for making these informative videos! Do you have any videos on how to replace rotted porch soffits? Ours are made of wood and out of place and it seems like its time for a replacement.

[@jttasb]

How was the bottom of the column attached to the deck? I did not see anything fixing it in place!