We've just had some new fencing installed, featherboard with capping rails on4" posts. All from Jacksons Fencing, pressure treated and 25 yr guarantee. Theposts have slightly sloping tops, presumably to encourage runoff. Should I putcaps on these posts to protect against rain? I'd need flat-top plastic withsides so I could cut one side off and slide it up to the fence. Trouble is allthose I've seen have pointy tops which would look a bit silly, sloping.

I don't usually bother with fence posts - the bases rot through at or just below ground level fast enough that capping them is largely irrelevant to their lifetime. I'm in wet windy North Yorkshire. YMMVI do cap (with lead sheet) larger wooden gate posts which makes them last a lot longer. Otherwise sooner or later the top splits and leaves and junk accumulate until something grows in the resulting hollow.

On Wed, 02 Nov 2022 05:49:45 +1100, Martin Brown

Do fence posts need caps?

Oct 21, 2022 Last reply: 3 years ago 27 Replies

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alan_m 3 years ago

There seems to be a vast difference in quality of the wood and treatment between the products sold in the DIY sheds, agricultural suppliers and that used for items such as power and telegraph poles.

I note that where I'm currently visiting the fences that are used by the nearby farm are held up with 6 inch round posts and are from complete 7 inch tree trunks that have only been de-barked, cut to length and have a point at the ground end. They don't seem to have been treated.

Power and telegraph poles are probably similar in that the are not cut from larger timer but are whole de-barked tree trunks and probably everything below ground was covered in a thick layer of bitumen.

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SteveW 3 years ago

Power/telegraph poles are still allowed to be treated with creosote. They are likely still sealed in a pressure vessel, heated and subject to creosote and steam (in the same way as wooden railway sleepers). This ensures that they are deeply treated and last for many decades. ISTR that you are right and the bottom ends are coated in bitumen too.

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Tim Lamb 3 years ago

Hmm. Treatment may not be obvious. Usually green for agricultural use and posts not always fully de-barked.

Some species are naturally rot resistant (Oak, European Larch...)

Utility poles are normally vacuum impregnated. North Sea gas had an impact on the availability of Creosote:-( together with public health concerns.

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farter 3 years ago

Don't see that here, no visible taper and they are a lot longer than fence posts.

No evidence of that either and to be effective it would have to extend above the ground after installation to protect at the air ground interface and be visible there.

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Martin Brown 3 years ago

They are routinely dipped in horrible phenolic coal tar (now something similar but a little less carcinogenic) and then hot bitumen over the top for the part that is buried. They last longer than gateposts as a result but you wouldn't really want to touch one.

They fall down at between 50-60 years from installation round here because Northern Powergrid CBA to do preventative maintenance so when one goes down in a storm it takes its neighbours with it!

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alan_m 3 years ago

I was just making the point that a power or telegraph pole is a complete de-barked tree trunk - not that it is the same diameter or length as a fence post nor that is has a pointed end.

Farm posts are often just pushed into the ground with a digger with the pointed end helping the process

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alan_m 3 years ago

last time I was staying here at the same place, away from home, the power company had a couple of helicopters travelling down the rows of overhead power lines and landing occasionally to check the condition of the wooden poles.

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farter 3 years ago

No evidence of anything like that with my personal power pole.

I have my own personal power pole because my house is further back from the road than normal and a flat roof, with the poles down the street on the other side of the street.

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