Fence Posts Held in Pea Shingle

[Jon McD]

Trawling this newsgroup for advice on extending the life of timber fence posts I came across one suggestion to ?concrete some pipe into the ground, put the post in and pack it with pea shingle?. Has anyone successfully tried this?

Compared to a post set directly in concrete it would seem to provide better drainage and in years to come it would be much easier to extract a rotted post and drop in a new one. However, I wonder if there is some ?gotcha? that has stopped this technique being popular.

Jon McD

[Tim Lamb]

In message , Jon McD writes

Soaking the lower 2' in preservative, irrespective of the post suppliers claims, is the first move.

I use crushed rubble or whatever small stuff comes to hand.

I think pea shingle might be too *fluid* and not give the support you need. The purpose of the concrete/whatever backfill is to increase the effective post diameter and stiffen the post in the soil.

regards

[Stuart Noble]

I think probably a little cement with gravel/shingle would give you the best of both worlds. Easy to break up if the post rots but firm enough not to wash away. I don't know what the "pipe" would be for

[John]

This is basically the way I put the posts for my gazeebo into the ground. Stone is better than pea shingle as it locks together better. It also allows water to drain away from the wood. If you set a post in concrete, you are basically making a bucket. This will fill with water that can't escape and the wood rots.

John

[Man at B&Q]

When you extract the old post, all the pea shingle falls to the bottom of the pipe and it's a bugger getting it out when you want to drop the new post in.

MBQ

[Andy Burns]

That's what the old nearly knackered hoover in the shed is for isn't it? That, and sucking the mud out of the stop-c*ck in the street (I got some strange looks doing that last year).

[Man at B&Q]

If it's one with a water meter, complain to your supplier that you can't read the meter. We got a free replacement.

MBQ

[Pete C]

In addition to the other suggestions I'd also coat the buried part especially end grain with bitumen paint. Otherwise it'll soak up water and remain wet for longer.

cheers, Pete.

[John]

Noticed the Highways use a similar technique - but use expanding foam to set the pole or crash barrier into a pipe concreted into the ground.

[John]

[The Medway Handyman]

AFAIA tanalised timber can't really rot - at least not for 30 odd years anyway.

[Roger]

The message from "The Medway Handyman" contains these words:

Fence posts usually fail at ground level.

[mail]

Failure at ground level is absolutey correct and the reason was discovered by Ed Baines at ICST in the mid '70s where he discovered that there was a wicking action of nitrogen salts from the buried end grain up to the ground level where it evaporated away the water leaving a nitrogen-enriched area of wood waiting for first the precursor stainers then the wood rotting fungi. It was at that point that the oxygen, moisture content and micronutrients were all right for the degradation to take place. Too low in the ground and its anaerobic - too high and the moisture content is not high enough. As what is the best approach clearly it depends on the water table and other factors but if you can follow the earlier suggestion of sealing the end grain (addtionally have it tanalised) and NOT cut a new sharp bit if already tanalised), having a draining medium AND painting or wrapping a material (such as polythene) around the stake or fence post at ground level and for say 300 mm below you will inhibit fungal growth considerably. I prefer a physical membrane "glued" to the post with say bitumen such that water entry is minimised from above and side penetration of the hyphal strands from the soil is eliminated

They will get there in the end but it will take time

Tanalised fence posts are normally (if I remember correctly) treated to 8kgs per m3 and have a design life of 50 years "normal" tanalising was about 4 kgs I seem to remember but am open to correction

chris

[Rod]

And the use of ordinary (AKA "canoe") foam? Might not set as fast, but given suitable interim support, do you think it would be dense/strong enough for a garden fence or similar?

[Stuart Noble]

Did he discover the wheel as well?

[Emil Tiades]

The wheel was rather useless until a real clever guy discovered the second wheel.

[mike]

In my experience of fence repairs ( which is in miles ) .... tanalised posts seemed to go brittle and break off at ground level. I would doubt a 4 inch round would stay upright anywhere near 30 years. We used to boil posts in creosote filled tanks and leave simmering for 24 hours ..... we would give a guarantee of 30 years for those.

[Rod]

And a really clever genius discovered (invented?) the axle?

[Roger]

The message from [e-mail] contains these words:

A good deal more experience than me but I have reset wonky fences where the posts could have been 20 years or more older and have lost less than

10% from breakages plus the occasional odd one that didn't survive a further mauling.

[Huge]

We just had the electricity supply poles to our house replaced, partly because of woodpecker damage (yes, really) and partly to get taller ones so the combine will fit under the power lines. The guys who replaced them said the old ones had been in at least 40 years. There was no sign of rot, and when they cut them down, they still smelled of creosote...