Fencing - maximum span?

[MadAlicesDad]

I am going to erect a 4 ft high wooden fence along a border to replace a wire fence. There are currently 4" wide concrete posts at between 2.8 and 3.1 metre intervals.
Whilst the council who installed the posts knew nothing about the use of tape measures to measure between posts, they certainly made sure they weren't going to fall over, and I do not intend to dig them out!
My plan therefore is to fix 4" wooden posts to the existing concrete posts using coach bolts, fix arris rails between the posts and nail feather edge board to it.
What I'm uncertain about is whether to do the whole 3m span in one go, or put intermediate posts in at nominal 1.5m. I've noticed that arris rails come in 3m lengths so this is presumably an acceptable span, but I would appreciate any thoughts anyone has.
The awkward bit is that this job is to be done at my in-laws 200 miles away and in a fixed time period so I want to be prepared and order enough timber etc before I get there.
Cheers,
Mike

 

[Thermo]

closeboard fencing can be done in spans of up to 3.6m. WHatever span you do, you need to ensure you use a centre stump for added stability. Its basically a 2" square peg that is secured to the bottom arris rail, the garvel board and then concreted into the ground, in the middle of the span

 

[MadAlicesDad]

Thanks for the info. if that's the correct way, then that's what I'll do. What I wasn't sure of was the need for a full size post to stop it sagging under the weight.
Cheers
Mike

 

[salynn]

Hi Thermo, but how wide does the hole need to be for the 2"x2" centre stump, to aid in stability. i have also a 3m bay and read that a centre stumpt was required. thanks

 

[Thermo]

the centre stump is literally a 50mm x 50mm peg, so the hole is just big enough to fit it in along with some concrete.

 

[salynn]

thanks for this. i have recently decided to replace some old panel fencing with closeboard and on one side and have 3 x 2.4m bays. in one of these bays in the centre was one of the old posts (now removed) which has left a small crater (12"x12"). from previous posts i assume ok just to fill with concrete, though not ideal, but will do the job.

 

[Thermo]

thats fine