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Replacing a fence

Posted: 17 Mar 2019, 11:29am
by freeflow
The recent windy weather has decimated a fence in the back garden, including the running the repairs I did after we had high wind damage several years ago. The fence was put in about 10 years ago by dodgy_contractors_r_us co ltd but was done badly as the concrete into which the posts were set wasn't high enough above ground level or wasn't sufficiently rounded so the posts have rotted at ground level.

So I'm wondering which is the best way to proceed. I'm quite a reasonable handyman. My current thoughts are to do a DIY replacement so that the job get done properly.

1. Take down the current fence
2. , dig out the old concrete (not huge amounts based on previous repairs),
3. Hire a powered post hole borer to get some good deep holes dug
4. Fill the holes with good quality concrete
5. Insert a long spike (750 mm) post holder that clamps the post (100mm square posts, up from 75mm)

Any suggestions on the hows and whats would be most welcome.

The fence is about 25 6ftx6ft panels long. I'd also be looking at putting in concrete baseboards to minimise the rotting I'm seeing at the bottom of the current fence panels.

Re: Replacing a fence

Posted: 17 Mar 2019, 12:42pm
by thirdcrank
If you intend to use the metal sockets, why not just bash them into the ground as intended by the manufacturer?

I'll offer one reason, which is that it's not easy to whack them in exactly vertical. That's not a big problem unless you plan to use ready-made fencing panels. If you want to avoid eventual trouble with your posts then from observing what neighbours have, I'd recommend concrete posts set in concrete. I've never used them myself but I've done all sorts with wooden posts over 50 years as a householder and they are the Achilles heel. (I know that concrete is open to criticism on environmental grounds but I see you intend to use concrete weather-boards anyway.)

Re: Replacing a fence

Posted: 17 Mar 2019, 1:15pm
by rjb
You can find reams of useful information here from 2015.
Must have been a windy spell then as well :lol:

viewtopic.php?f=15&t=95625&hilit=Fence+Posts+Concrete:

I see you managed to keep it going for 3 years. :roll:

Re: Replacing a fence

Posted: 17 Mar 2019, 2:57pm
by Ben@Forest
The alternative is do not use concrete at all. It has been shown that concrete setting rots fence posts quicker (because the tiny movements always occur at the point of the concrete level creating a stress point).

Set each post deep enough and tamp down broken brick, stone or even some of the concrete you've extracted from the original posts with plenty of earth. You don't need to use concrete at the base, simply use wooden kickboards. They can be replaced as or if they rot.

The long term plus is of course that there's no concrete lumps to extract if you do have to replace posts. And they last longer. I used the above method with softwood pressure treated posts about 12 years ago. Looking good so far.

Re: Replacing a fence

Posted: 17 Mar 2019, 5:56pm
by rjb
As an alternative has anyone any experience of post and rail fences made from recycled vehicle tyres?. They should last a lifetime as they will never rot.

Re: Replacing a fence

Posted: 17 Mar 2019, 7:46pm
by Paulatic
Don’t know about ones from recycled tyres but have experience of plastic ones made from carrier bags. These are made near me and I began using them o the farm around 15 yrs ago. They certainly haven’t rotted so far. The thinner stobs can be a bit whippy when melling them in. I’ve some heavier ones at home hanging a gate from and they are sturdy.

Re: Replacing a fence

Posted: 18 Mar 2019, 12:52am
by peetee
If the fence is prone to catch the wind then I would recommend concrete footings and a 3ft concrete stub post to which a wooden post can be attached. By keeping them up off the ground even bog-standard pressure treated posts from B&Q last ages.
Set the first one in and fix the first panel to it, propped up level near to the other end. This will give you an exact distance for the next post, and so on. I did this at my last house and it was straight and level and lasted the 10 years I remained there.

Re: Replacing a fence

Posted: 18 Mar 2019, 6:11am
by pwa
Wood embedded on concrete will rot at ground level. You can delay it through various measures but it will happen in the end. Putting steel in the ground instead is a better idea.

The metal ends come in different shapes, some pointed and some not. I would dig the holes using a spade and a bar. And i would try to finish with holes that have firm sides. A lump of concrete in a hole with fluffy, insubstantial sides will move around in the wind. The holes need to be wide enough to take the post and allow your mixing stick to go down each side.

I would attach the metal to the post prior to putting it in the ground, as it is easier that way. Use the quick setting concrete intended for fence posts. You have to mix it well, and get the water properly mixed in, in the hole. It starts to go off in a very few minutes and withing ten or twenty minutes feels stiff. You need to get the post positioned on the line, at the right spot and the right height. The best way of doing that is to install the panels as you go along, so that you are digging and installing a post at the end of a panel that is already held in place at the other end. So take it slowly, possibly over a few days.

To maximise the life of all components I would paint the metal inserts with a suitable paint prior to installation, and apply wood preservative to the ends of the posts going into the inserts.

Again, take it slowly, measure everything and have your spirit level with you at all times. You are not a professional and should not try to go at professional speeds.

And don't do it on a windy day.

And be very careful when you are digging because you may find underground pipes. I once went though a sewer pipe and repairing it was not the most pleasant job I've done.

Re: Replacing a fence

Posted: 18 Mar 2019, 7:10pm
by Norman H
+1 for concrete spur posts.

Bolt the timber posts to the concrete spurs clear of the ground by using steel studding (cheaper than coach bolts). Digging out the old concrete post fixings is hard work. I'd avoid this by starting with a half panel or better still a length of traditional feather edge and arris rail adjacent to the house. It's not a bad idea to make this a bit higher than the rest of the fence, for extra privacy.

Re: Replacing a fence

Posted: 18 Mar 2019, 11:34pm
by drossall
thirdcrank wrote:If you intend to use the metal sockets, why not just bash them into the ground as intended by the manufacturer?

I'll offer one reason, which is that it's not easy to whack them in exactly vertical.

I found them pretty good. I checked with a spirit level at regular intervals. Ended up slightly off, but not enough to prevent use of standard panels as you mention.

Somewhat regrettably, our neighbour, with my agreement, had a contractor remove my Metposts, because the fence was generally dilapidated, and put in concrete instead. It was done about as well as the OP's, with the particular issue that the neighbour's land is slightly below ours in level, so it wasn't easy to get the concrete deep enough. Started falling over almost immediately, and much harder to fix than replacing a wooden post in a Metpost was.

Although I did have one issue where the Metpost had rusted away over a couple of decades. Try getting that out and replacing it!

Re: Replacing a fence

Posted: 19 Mar 2019, 10:39am
by Norman H
Leaning concrete posts can be straightened, especially at this time of year when the ground is damp.

Attach a guy line to the top and apply gentle tension over a number of days. 25mm ratchet straps work well, or a rope with a trucker's hitch.

The same technique works for wooden posts but there's a greater risk of snapping them if they're not sound.

Re: Replacing a fence

Posted: 19 Mar 2019, 8:21pm
by irc
I have some 4*4 Wooden fence posts in my garden still sound after around 28 years. Set in concrete with the portion below ground painted with bitumen paint. Concrete an inch or so above ground and sloped away from the posts.

The 6*6 panels have been replaced a couple of times on the same posts.

I tried metal sockets but hard clay 18" down meant I was needing to dig deep holes anyway to get the sockets in so I spent the cost of sockets on postcrete instead.

Re: Replacing a fence

Posted: 19 Mar 2019, 9:54pm
by drossall
Norman H wrote:Leaning concrete posts can be straightened, especially at this time of year when the ground is damp.

Attach a guy line to the top and apply gentle tension over a number of days. 25mm ratchet straps work well, or a rope with a trucker's hitch.

The same technique works for wooden posts but there's a greater risk of snapping them if they're not sound.

Still needs a lot more concrete though, or they'll fall over again :(

Re: Replacing a fence

Posted: 19 Mar 2019, 10:30pm
by fausto copy
Plant a hedge; much more environmentally friendly and a lot nicer to look at. :mrgreen:

Re: Replacing a fence

Posted: 22 Mar 2019, 9:52am
by alexnharvey
I faced the same situation about two years ago, posts which had rotted at the base were blown over by the wind. A fencing contractor installed concrete spurs and we retained the existing fence which was bolted to the spurs.