How to try to prevent wooden frence posts rotting?

[ABN]

About to put up a new fence using wooden fence posts, don’t like concrete ones. There will be a small brick wall, about 2 bricks above ground level running between them with the fence panel sitting on top of them. Will concrete the posts into the ground.

Was wondering if there is any additional treatment that I can give the posts, to try to delay the rotting process, before I fit them. Was thinking along the lines of painting the part that will be underground with a bitumen paint? Would that help or can you think of anything that would help?

 

[JohnD]

Soak them in a bucket of Cuprinol Green for 4 days. Must reach at least 150mm above finished ground level. Brush the rest with several flowing coats.

Soak the top 150mm as well because the rain will get in.

Or use concrete posts and paint then with dark brown masonry paint to blend in with the timber, like I do.

Or you could even use concrete spurs, and bolt timber posts to them with the bottom of the post 150mm above ground. I do that, too.

Softwood fence posts are a terrible idea.

 

[Thermo]

yes concrete do look terrible painted or not!

its worth going for a larger post such as a 100 x 100. you will get a decent life out of any post, especially the larger ones.

 

[megawatt]

Do like the farmers ... Stand the posts in bitumen (up to ground level) for 5 minutes and then remove and let dry before sinking ... They'll last decades

 

[ABN]

Was wondering if that would work. Didn't know the sience of why wood rots so wasn't sure if putting a waterproof coating on would help or increase the rot since any damp would not be able to escape. But if its good for the farmers it good for me.

Thanks for the replies

 

[JohnD]

wood doesn't rot (much) if it's completely wet or completely dry.

So the part near ground level that has both air and water rots fastest.

So if you are using bitumen I think you need to protect the wood 150mm up from the ground, as (1) soil might build up round it (2) rain will splash up

 

[megawatt]

Wood doesn't take in much moisture across the grain i.e. from the sides of a post, it takes in far more through the end grain using capilliary action.

Anything which permanently seals the end grain will extend the post's life the longest.

If you examine a post which has broken off at ground level you will clearly see the effect of this.

Farmers have been using bitumen in this way forever and their posts last far longer than anything else I have come across.

Problem with bitumen, though, is that it doesn't look great and hence only do the bit which won't show

 

[ModernMaterials]

re: protecting the end grain at the bottom of the post.

one school of thought suggests that a 2" layer of gravel below the post with the concrete layed on it will allow water to drain away from the bottom of the post.

i.e. tamp down a layer of gravel and then sit the post on it. Then pour the concrete around the post.

as opposed to: bash a brick down, sit the post on that, then pour the concrete.

 

[megawatt]

Do both

 

[Deluks]

The gravel trick won't work in clay, the void will soon fill up with water.
Which just gave me an idea, coat the bottom of the post in clay, and fire it in a kiln.
Ok, it's just a crazy plan I just cooked up, some would say it's half baked.

 

[breezer]

yes concrete do look terrible painted or not!

not that bad.

 

[Thermo]

as i said concrete posts and boards look awful painted

 

[JohnD]

no they don't

 

[noseall]

wood doesn't rot (much) if it's completely wet or completely dry.

So the part near ground level that has both air and water rots fastest.

this statement is very accurate.

 

[masona]

no they don't

Don't start

Nah, cover the concrete with timber