Hi, I'm looking for a bit of advice if thats ok.
We need to erect some new 10m rugby posts before the students return. The query is, how much concrete to use?
I'm in two minds as to weather a 6-8 inch post hole bored out to the depth of the sockets -approx 90cm- will suffice or, weather we will need to;
a) go deeper with the hole borer
b) go wider, either all the way down or at the base of the sockets
Does anyone have any suggestions?
Ether way they will need to withstand two things.
1.The occasional student bumping into them with a ride on mower
2. The occasional student treating them as a climbing frame when they think no one is looking!
Many thanks in advance!
James, holes should be a 1m cube, concrete wise, we just a few weeks ago installed new sockets and used 1.6m3 of concrete ( 2 sockets) , you need to leave 6-8" at the top for soil.
we used a complany that mixed it on site, saved us hrs in terms of mixing, and cost about £270.00
I have some photos that i will up load tomorrow.
25 Aug 2010 by vid
Ask the socket manufacturers - it normally states the amount needed in a leaflet inside the socket pack. A cubic metre will certainly do, this would support posts 20m high I should think. Last time I erected 10m rugby posts they were 700mm deep we used a 300mm post hole auger to a depth of 1m we have also done them at 225mm 1m deep - neither have moved after 5 years but we just thought the 300mm size would give better protection against movement at a school. Put in 1m deep in clay loam and allowed to settle the posts wouldnt move that much without concrete. Personally to be extra sure I would go for 400mm. Either get rapid setting concrete, or very lean so that you can get the uprights set exactly right straight off. With posts that tall the slightest discrepancy can look awful.
Vid, what we done was after the holes were dug ( by a very friendly contractor with a digger!!!) we set the sockets with postcrete, then the next day had the cement come in, we found this stopped the sockets moving during the pour, and negated the need to support the uprights in situ. In the past we have had to tie off the uprights, to get them plum, which frankly is a pain, as any idiot can just give them a tug and all hard work is undone
No doubt next Tuesday when we erect them will be the telling issue if we got it right!!!
25 Aug 2010 by Mike
We're just installing 3 new sets of 7m posts now. The sockets are 914mm deep, and the lip of the socket should sit 25mm below the grass surface according to the instructions. rule of thumb that I work to is that the hole that you dig should be as wide as it is deep, so in our case, our holes are 914x914x914mm, or a little bit more.
Mike
26 Aug 2010 by vid
a cubic metre of concrete is about 2 tonnes - you could have that block on the surface and it wouldnt fall over!! we had 7m wooden posts that were about 180mm at the base - the ground was always too hard to go deeper than 800mm the 'slot was slightly wider than the post and when upright had a piece of 3x2 hammered into the ground behind it and the long pieces of any old timber hammered around it to hold it in place - they never moved - no concrete or sockets. I'm sure you are all just being ultra safe but it really is overkill you just wont need that much unless its pure sand or peat!!
Now here is a conundrum...
Do what you think is ok? what is ok?
Do what the manufacturer recommends?
Put too much concrete in or not enough, what is enough?
Posts fall over......... hits a kid
Hhmmmm, could read the label and only be put in by experienced competent trained persons...
Plastic.... it's The End I tell you... THE END!!!!
26 Aug 2010 by JamesG Last edited 26 Aug 2010
Cheers for the feedback guys plenty of food for though.
I did ask the manufacturer who recommended they need concreting in but didn't specify quantities. I'll wait to see if any recomendations come with the posts when they arrive next week and then go from there, bearing in mind your advice.
26 Aug 2010 by Mike
James - if your new posts are manufactured by Harrod's, which i'm assuming they are, there will be an instruction sheet with them which you should find rolled up inside one of the posts or sockets.
26 Aug 2010 by vid
Fall over Barry?? These are a metre in the ground, move maybe, wobble maybe. But fall over I dont think so unless the kid is standing under them when the helicopter hits them - then they might fall over!!
Lol @ vid, was being devils advocate, throwing the lines on other competance/training/experience posts and replies....
Depends totally on soil type, depth as you say but what if a post only wobbled enough for the crossbar, not fitted properly or corroded bolt fell on a kid... its not only possible it happens alright less likely on rugby, but possible the same. More is better than poor quality or not enough.
Plastic.... it's The End I tell you... THE END!!!!
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