As these things seem to rot at ground level and just below but not above, then perhaps the remedy is to seal with bath sealant where the post enters the concrete, and then smear further sealant up the post for a further couple of inches above ground level to prevent extended contact with water?
gareth scribbled
Or wrap the lower part of the post in plastic, which won't rot for 200 years. Course it'll also trap moisture in the wood too.
Even pressure treated timber will rot eventually. What I do is either use concrete spurs or posts or ensure than the post hole is well drained.
That is the problem, if the wood has to be below ground the only answer is good pressure treatment and excellent drainage.
In message , Mark writes
Dry soil is not necessarily good.
I am replacing some treated softwood post and rail installed about 20 years ago. All are suffering from *footrot*. The *dry* ones next to some established conifers have about 18" of powdery rot with 6" only left extractable from the bottom of the hole.
Where the soil is more moist, only the first 6" has fully rotted with the rest sound enough to grip and extract.
None of my usual suppliers have stock on Creosote but I was able to get some delivered from Creosote Sales Ltd. You need to be a professional user:-(
I would simply use oak, as I did for a pergola. Twenty years on, it still shows no signs of rot.
Don't use concrete it just traps water in the timber. It's not needed anyway provided there is enough post in the ground and the soil well firmed in from the base of the hole up when the post is installed.
It's not so much the water as the availabilty of water that is the problem. Posts rot at or just above the ground level as that is where the conditions are "just right" for the wood rot fungi/bacteria WHY to thrive. In the ground is generally too wet, up in the air too dry. Capilary action from the wet timber in the ground to the dry timber in the air maintains a damp gradient and the just right conditions along that gradient.
All I can see sealing doing is moving the position of the just right conditions. Well treated, good quality, timber preferably pressure treated with CCA (if that hasn't been banned...) or submerge the posts in proper creosote for 24/48 hours or at the very least stand the ends in creosote to at least a foot above where the ground level will be again fro 24/48 hours. A good couple of liberaly brushed on coats of creosote for the in air portion.
I think the best you can do is pack the post with a free draining material like gravel. A weak cement/gravel mix drains well and is easy to knock off when the post needs replacing. ISTR reading on here that this is the most cost effective strategy for agricultural applications.
It might be worth considering drilling a hole (1/4" to 1/2") to the depth of the centre of the post - about 3" above the ground, and at an angle of 45 degrees. Every so often, top it up with your favourite preservative (several fills, and allow the preservative to soak in well), then fit a water-tight bung.
You'd think that if that was a useful approach, someone would have tried it and found it works better than not doing that and the word would have got out about that by now.
Presumably it doesn't work because you need to pressure treat wood for the preservative to work.
In message , Jacko writes
It's amazing how many things are not used simply because no one has thought of them - or if they have, hasn't bothered to try them.
This is intended to 'top up' the original pressure treatment (which, of course, doesn't last for ever). If unpressurised water can permeate the wood, so can preservative. Even if it doesn't help, it's unlikely to do any harm.
Not with something as common as rotting wooden fence posts.
Sure, but if it doesn't soak into the wood when not under pressure, there will be nothing to top up.
It's doing that with the outside of the post.
Not necessarily with a hole inside the post.
Sure, but it is unlikely to stop the wood rotting where it is in contact with wet soil or concrete.
In message , Jacko writes
If you fill up the hole, and leave it for an hour or so, you will probably find that the preservative has vanished. Where has it gone? Has it evaporated? No - it has soaked into the wood. So you top it up a few times more, until it the wood has absorbed as much as it can. If you repeat the treatment once in a while - especially when the post is getting a bit old and the original preservative is becoming less effective, I think you'll find that it will forestall the evil day when the rot eventually begins to set in.
Unlikely, and if it does, your scheme won't work because you'd have to keep filling it up again every hour.
If it's gone in an hour, it's much more likely it has run out a crack.
Which is very unlikely to be anywhere near the outside of the post which is where it will rot.
There's a reason posts are pressure treated.
It won't. That is why posts are pressure treated.
/Jacko/q
Fuck off woddles
Jim K
In message , Jacko writes
You're completely missing the point. As the wood becomes more saturated, the preservative takes progressively longer to disappear. If it continues to disappear, the wood is very porous - which is probably an indication that it won't last long without continual TLC.
In which case, you should take care to choose better posts when you next buy some.
But it doesn't last for ever. Even telegraph poles have a rot-by date.
Which doesn't last for ever.
However, I will leave you to bow to your superior experiences in such matters.
In message , Ian Jackson writes
I think this would work if you have the patience:-) Telephone poles are routinely dug around and then treated with some chemical preservative.
Look up Boron as a timber preservative.
Some years ago, I noticed what appeared to be large nails hammered into timber electricity poles at ground level. The guy I asked said he thought they were to extend the life of the pole.
No.
It won't with the preservative in a hole in the post.
In practice it won't soak into the wood enough to matter.
That is why pressure treatment is used.
The post is cracked.
Pouring preservative into a hole in the post won't see it last any longer than not doing that, because the preservative won't get anywhere near where the water gets to on the outside of the post below ground level.
Bit late for that once the fence is done.
Yes, but putting some more in a hole won't change that.
Yes, but putting some more in a hole won't change that.
I don't bow to anyone. I do understand why posts and poles are pressure treated.
AIUI the reason for pressure is to arrive at a greater depth of preservative that would arise from just soaking and capillary action alone.
It has nothing to do with the permeability of the wood otherwise, as another pointed out, rainwaterwouldn't be a problem.
Therefore the suggestion by G3OHX is a good one.
In message , Tim Lamb writes
It's not an alternative to pressure treatment. It's just something you could try when the post's getting a bit old - something to be done on a fine day in between doing other more important DIY jobs.
Not the old ones. I personally know poles that are at least 70 years old, and as far as I know, have never been given any maintenance.
I've never heard of that. Is it possible that something leaches out of the nails if the wood is soaking up water (and therefore more likely to rot)?
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