How to fix rotted timber post?

j1111

well? or is it too big a void? i dont really want to get into taking it down and sawing it off.

MitchellMc

From the photo, it looks like the entire base of the post has rotted, and it’s no longer bearing its weight on the support. In this case, using bog isn’t suitable. Bog is purely an aesthetic filler for non-structural areas and cannot restore the strength needed for a post that carries weight. The vast majority of the post is decayed, so it’s no longer structurally sound.

The only safe options here are to cut the post back and extend it with a new support or replace the post entirely. Regardless of the approach you take, ensure that you take proper precautions, as working with unstable posts can be hazardous. Ensuring the post is properly supported before any work is key to avoiding accidents. I highly recommend enlisting the services of a professional to repair this issue.

Please let me know if you have any questions.

Mitchell

j1111

its not load bearing just a cosmetic post at the entrance. maybe some expanding foam topped off with bog?

MitchellMc

I’d need to err on the side of caution here @j1111. Standard post construction relies on the footing to hold the post securely, so simply filling the void with expanding foam and topping with bog without addressing the underlying issue would be ill-advised. Is the post connected elsewhere, such as to a wall or other structure? My concern is that if a substantial footing was installed for this post, it’s likely there for stability, even if the post appears purely cosmetic.

If you are certain the post serves no structural purpose at all, you could technically fill the area, but given the size of the void, builders’ bog or foam alone might not be adequate. My main concern is how the post is being held in position. If it isn’t supported properly, a cosmetic fix could fail or shift over time.

Let me tag @Nailbag and @Dave-1 for their thoughts.

Mitchell

Dave-1

Good Afternoon @j1111 .

Any fill would be a no no due to its not connected to anything anymore. Even a cosmetic post is carrying its own weight so the only thing holding that post up is its attachment above. Expanding foam and bog as you suggested would be opening a bad case of a can of worms safety wise.

Id use a prop and stabilise the roof first.

Then remove and replace the post like for like. (You can do a lap styled joint but I find that it doesnt look as nice)

When replacing with a new post, leave an air gap of 20mm under the post to help stop the post rotting again. I use a temporary scrap piece of timber just sitting under the post until its bolted in.

If one post has rotted I would check the others for issues, especially if the posts are sitting flat bottomed in the stirrups.

Dave

j1111

it'll cost a bomb to replace the post since its a big merbau one, its not really being supported at the bottom so the rot is really just unsightly.

i might just build a box around it to hide the bottom as a temp measure.

Nailbag

Hi @j1111

I guess the first point of concern already mentioned and answered, "is the post load-bearing?" which answered no. Then the next thing is to how to repair/fill the void? Next is how did it get into a state of complete deterioration at that point? Because if not addressed then potentially whatever repair will be at risk. So, you need to investigate and prevent.

You have a stained timber post so, regardless of its strength or not, fillers including builders bog will be a 100% make-shift repair, and be a cosmetic eye-sore.

I think your idea of building some form of decorative box around the bottom is an excellent one. But you still need to do a proper repair or the rot will make its way up and out eventually.

Like any cancer it needs to be cut out a little further away from the source. then apply Earl's wood hardener and prime coat. This should stop it at its tracks. Though unseen I would still go with an overlap join as per the image as any cosmetic only fix in my mind is unacceptable. It can be any suitable external timber because it's going to be covered. Then you can box it up.

Nailbag

j1111

Thanks for the feedback, yeh its because as you can see in the pic theres are number of deep cracks running down the length of the post.

As this post is by the entrance and not sheltered by the eaves Its likely overtime the water has gone into the cracks and made its way to the bottom of the post where its rotted out. This is all before i got the house i noticed it from the inspection but i underestimated the price of replacing the whole beam.

Anyway I think I'll seal or bog the cracks to stop further water then just saw the bottom of it off as I'm confident its secured fully from above and put some replacement structural timber in the gap then box it off.