Durability of chestnut fencing

[misterfish]

We need to have some new perimeter fencing and like the look of cleft post and 3 rail chestnut fencing.

What we can't find out is how long it should last. As we're going to need at least 100 metres (which won't be cheap) we want it to remain in decent condition as long as possible. Any info or experience of relevance much appreciated.

Misterfish

 

[Woody2Shoes]

Hi - I have a 100m run that looks very similar to your photo. It's still in pretty good shape after 15 years or so. The rails will probably go on indefinitely. The posts will eventually rot where they are in contact with the ground - so thicker posts should be worth paying extra for. In my experience, the pointy ends of fence posts need to be able to dry out in dry periods (concreting in a post tends to trap moisture in the post and greatly accelerates rotting). I also think that three rails is definitely better than two. You can always add stock netting and/or electric tape unobtrusively if you need to. All round a good choice I reckon! Cheers, W2S

 

[misterfish]

Thanks for that - we'll now get some quotes.

Misterfish

 

[MikeG.]

How do they fit the rails? It can't be after the posts are fixed in the ground......so I guess they fit them in before driving them post home. However, that would mean the slots would have to be quite loose.

 

[MattRoberts]

There's a fair amount of this type of fencing near me. I've no experience using it myself, but as an observation, I've never seen a fence like this in decent shape - always rotten, loose or broken...

 

[custard]

In terms of durability, there's not much difference between Sweet Chestnut and Oak, they're both rot resistant, strong, and with very high tannin levels. Indeed on commercial plantations the two species are often grown side by side, the reason is that even though Sweet Chestnut is cheaper than Oak it reaches maturity sooner by virtue of it's thinner sapwood band, so it can be felled and bring in some income that bit quicker.

Incidentally, Sweet Chestnut is different to Horse Chestnut, which has very little strength and rots as soon as look at it.

 

[Woody2Shoes]

In terms of durability, there's not much difference between Sweet Chestnut and Oak, they're both rot resistant, strong, and with very high tannin levels. Indeed on commercial plantations the two species are often grown side by side, the reason is that even though Sweet Chestnut is cheaper than Oak it reaches maturity sooner by virtue of it's thinner sapwood band, so it can be felled and bring in some income that bit quicker.

Incidentally, Sweet Chestnut is different to Horse Chestnut, which has very little strength and rots as soon as look at it.

I think the biggest contributor to longevity, besides tannin content, is that the timber is riven, not sawn. I also suspect that because chestnut is not indigenous, but oaks have been growing here since at least the last ice age, that the microscopic lifeforms that eat wood are more evolved to eat oak than chestnut - but I have no evidence to support this hunch! And yes, oak has a lot more sapwood.

I wonder if the delapidated fences as seen upthread might have sawn, not riven, posts. I think that one of the most attractive things about this kind of fencing is the slightly wonky, rustic, look - especially when the surface starts to weather and accumulate lichen etc.

Oak is seldom coppiced (although it can be). Nearly all sweet chestnut is coppiced, and this partly contributes to its speed of growth - you have a large, well-developed root system driving proportionately much smaller top-growth. To coppice effectively, you need relatively large - say 2 acres or so - patches, of the same species, that can be cut in one season - in a rotation of say 10 years. Any smaller area, and the risk of shading becomes greater and the new growth will be less vigorous. That said, I think that slower-grown chestnut e.g. on a north-facing slope can be more durable (I guess a tighter grain structure) and command higher prices.

The mortices in the posts are often a bit larger (esp. along the grain) than they strictly need to be to make the fence easier to assemble/repair and to allow for natural variations in the "tenons" on the rails. A chain morticer is the top tool for the job.

Cheers, W2S

https://www.woodlands.co.uk/blog/practi ... roduction/

 

[Woody2Shoes]

Here's a couple of examples on heavy weald clay:

The first one shows a 25-year-old fence with sawn oak posts and riven oak rails (note insect attack to sapwood along bottom of rail). Note also nails used to keep mortice in tenon. Nearly all posts have rotted underground - I've shored them up with bits of angle iron driven in alongside.

The second one shows a 15-year-old fence with riven chestnut rails and riven chestnut posts - fingers crossed, none of these have shown signs of rotting out and no sign of insect attack to (almost non-existent) sapwood. No nails used in this fence.

Cheers, W2S

 

[misterfish]

Thanks for all that info. I'm sure we'll go for the cleft chestnut fencing- it looks good and seems to have a decent lifespan.

Misterfish

 

[Jamster21]

We have fencing in this style put in after the farm was opencasted in the 1940-50's. This fencing is therefore at least 60 and when it hasn't been lent on by large farm animals, is in fantastic condition still. I've reused a few rails as coat racks, etc with just a sand and wax, and I've got a few posts stashed away for an as-yet-undecided 'project'. We think its probably oak - its incredibly hard and can't have nails put into it even now... If the price difference isn't too much, you'll not go wrong with oak, even if you consider sweet chestnut for the rails to address the cost?