How to repair rotten timber post on deck?

Hi, I’ve uncovered a rotted section on timber post on my deck. I’ve scraped back the section - see pics.

My first thought was to make good again with builders bog. But that’s a big area to fill in and might be hard to make the builders bog blend in with timber around it.

Would I be better to cut out the rotted section and insert a new piece of timber?

Any suggestions would be welcome!

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Comments

iveg

Hi John,

Looks like a case of wood rot. Builders bog would only be a band aid fix, you could use nails inserted into timber to support the builders bog, but eventually it will still deteriorate. Yes best option replace the entire timber with treated pine. May be more work but you won't regret doing it. All the best my friend.

Akanksha

A warm welcome to the Bunnings Workshop community, @john12345. We're delighted to have you join us and trust you'll find the site a handy resource for all your D.I.Y. projects.

Thanks for your question on repairing your deck post. It's been an unusually busy time on the site but I'm sure our resident Bunnings D.I.Y. expert @MitchellMc will be happy to assist as soon as he can.

Let me also mention our ever-helpful members @JoeAzza, @Jewelleryrescue, @DIY4Knuckleheds and @maknilsin to see if they have any thoughts.

While waiting, you may also want to read these previous similar discussions in case they help:

How to restore a rotted timber post? by @johany
Front fence post repair corner rotting timber by JoeAzza.

And if you were also planning on restoring your entire deck at some point, we also have this popular step-by-step guide by experienced renovator @Adam_W that might come in handy: How to renovate a timber deck.

Hope this helps.

Akanksha

Jewelleryrescue

https://www.workshop.bunnings.com.au/discussion/comment/33294#Comment_33294

Hi @john12345 I wish I could say this was a fill situation but that timber way past its saftey margin.

@iveg Is right that post is due for complete failure. That post out of the photo can be also structual possibly holding up verandah roof (so do support the roof to stop it sagging when you replace post.) In any case that post is supporting a stair railing and must be structually sound to protect people in case they stagger and need support from hand rails etc, they cant be grabbing half rotted timbers.

The strongest way it to replace the whole post for you peace of mind and pre paint the new post after you cut it to size to stop premature wood rot into the future.

Replacing the post can be done just make sure the roof and all key connecting bit supported in place prior to post gentle removal like floor joists etc as when they sag it is hard to reposition them and might stress the surounding structure.

Feel free to ask more questions 🙂

JoeAzza

Hi @john12345 , I agree with @Jewelleryrescue and @iveg, maybe too far gone for repairs

i have done similar repair to two posts a few years ago, using treated pine decking for repairs, I have attached photos for you to see, however , it looks like one of posts may be starting to deteriorate again, I think I will have to revisit the problem.

Jewelleryrescue

https://www.workshop.bunnings.com.au/discussion/comment/33306#Comment_33306

Hi @JoeAzza There are no rules that say you cant transition to aluminum or steel as an option for longer life less maintenance

Dave-1

Afternoon @john12345

Ouch 😕 Yeah time to replace the post I think. Im pretty much following everyone here 🙂 The general rule of thumb I apply to timber rot is anything over 1/5th of whatever it is and it gets bumped up the list of "needs to be replaced" With your post being the attachment point of two handrails and the post to the roof it needs to be structal and not just a repair section.

As @Jewelleryrescue mentions you will need to support the roof while you replace the post. Not hard and may seem a bit of pain but way better then the roofline sagginga nd "crunch" downwards on you. 🙂

Has the rot spread into the handrails at the attachment point?

Dave

john12345

https://www.workshop.bunnings.com.au/discussion/comment/33316#Comment_33316

Good point about the handrails, I’ll check what they look like. Hopefully they are still ok

john12345

https://www.workshop.bunnings.com.au/discussion/comment/33294#Comment_33294

Thanks all for your thoughts on this one. Looks like the group agrees replacing the post makes most sense! Cheers all @iveg @Jewelleryrescue @JoeAzza @Dave-1

MitchellMc

https://www.workshop.bunnings.com.au/discussion/comment/79004#Comment_79004

It's great to see you've received solid advice from the team @john12345!

Just to jump on the bandwagon, I wanted to re-iterate the concern if this is a structural post holding up a verandah roof. Not only does it need to be replaced, but you need to get props in there immediately to support the roof. If this post does support the roof, I would strongly suggest you enlist the services of a professional and keep everyone clear of the area until the props are installed to support the roof.

Mitchell

john12345

https://www.workshop.bunnings.com.au/discussion/comment/103807#Comment_103807

Thanks that’s a good point @MitchellMc

JoeAzza

https://www.workshop.bunnings.com.au/discussion/comment/33306#Comment_33306

Hi @john12345 ,

I have just finished repairing one of my posts, I thought you might like to see the result, originally repaired using cypress pine picket fencing timber, this post was repaired a few years ago, it was showing cracks and what I thought was rotting timber, so I decided to check and re repair it, to my surprise it was in good condition, I routered the cracks using a v shaped router bit and a straight router bit, I then made a mixer of waterproof glue and cypress pine saw dust, let it dry overnight, sand back patched with an outer filler sanded back and repainted, see photos.

Jason

https://www.workshop.bunnings.com.au/discussion/comment/79882#Comment_79882

Great job as always @JoeAzza. Many thanks for sharing.

Jason

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/79882#Comment_79882

Morning @JoeAzza

Nice work, and nice way to bring it back 🙂

Did you support the roof while you had the post out or was theotherpost enough?

Love the "horses" you used to work on the post 🙂

Dave

JoeAzza

https://www.workshop.bunnings.com.au/discussion/comment/104391#Comment_104391

Hi @Dave-1 , I did use a supports light weight support, probably wasn’t needed , the other post was enough to support the roof section.
as for the horse, mostly used for supports when painting long pieces of timber😀

Photo of support used.

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/119279#Comment_119279

Morning @JoeAzza

🙂 Love it! Always better to be safe then sorry, Done that too many times.

Thank you for the pic 🙂

Dave

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