In article ,
Simon Avery wrote:

Untreated softwood lasts 5-10 years. (Dependant on soil
conditions) Treated, 10-20 years. (Larch can do this
untreated) Some hardwoods (split chestnut, oak, willow)
will last 50+ years untreated.
NM In the UK, just below soil level? You jest, sirrah!

Nope - softwood is my own experience (been fencing for about 15
years). Hardwood - from rough dates given by other fencers, locals -
you'll have to wait a few more years if you want my own experience of
it though.

Well, my figures are from both my own experience and that of many
other people. But see below why.

NM From experience, softwood lasts 1-2 years untreated, and
NM chestnut or oak sapwood (the former well creosoted) about 5.

Good god man, what are you doing to the poor stuff?

See below.

Even sawn untreated softwood, which rots fastest of all (opposed to
round, split or half-round) lasts longer than 5 years. Round untreated
softwood posts I put in ~15 years ago are still standing soundly (At
Greenaway house estate - to replace fences completely smashed after
the '87 storms). I know they're untreated because we cut them
ourselves from local Douglas Fir, Scots Pine and Larch.

I can witness the same, leading to weakening to the point of just
snapping in under 2 years. Not once, but many times.

Done a fair bit of fencing on Dartmoor, even across bogs - possibly
the most hostile environment in the South; where split chestnut lasts
for 30+ years (even if it looks like a hundred years old after a
single year). Oak's also used, often split, sometimes sawn, and that
lasts for almost as long.

That is the point. Dartmoor is perhaps the LEAST hostile
environment in the south! I am talking about the alluvial soils of
south east England, which ARE among the most hostile.

The reason is that it isn't the water that causes the trouble, but
the fungi. There are MANY more wood destroying fungi in the richer
soils, and they thrive MUCH better. Peat is a very effective
preservative, but even poor, acid soils aren't too bad. Absolutely
the worst for fungal attack are the rich, slightly alkaline loams.

NM I haven't got much experience of the heartwood, but it
NM certainly lasts a lot better. Yew is the ONLY British tree
NM that I know of where the sapwood will survive being embedded
NM just below damp soil level for more than about 5 years.

True, Yew is an exceptional tree. The only one (AFAIK) that doesn't
rot at all, hence the excessive age of some of 'em. Tad tricky to get
it in enough volume to be commercially considered though.

It rots, too - even the heartwood. Just very slowly.


Regards,
Nick Maclaren.