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Posted: Mon May 09, 2005 8:50 pm
by Onlyme
Hello Everyone,
this is my first post on the forum and was hoping you could give me some advice on the following 
: -
I'm installing 10 ft slotted wooden posts (5" x 5") with 6" gravel boards and 6 ft T&G fence panels and just wondered if my method sounded okay.
I've dug the holes 2' 6" deep x 2 ft x 2 ft square and intend to put in a base of 6" gravel then plumb my first post into position and brace with 2" x 1" batten. Fill hole with 8:1 concrete and wait until set (next day).
Screw gravel board to first post and support level temp. with bricks or wood etc. then screw panel to first post. Offer up second post to panel and gravel board ensure plumb and level with first post. Then brace with 2" x 1" batten.
Install next few gravel boards, panels and posts (about 3 or 4 posts with panels per day).
Then fill all posts with concrete and tamp down whilst checking they are still plumb and level.
Next day do a few more.
my neighbours land is about a ft higher than mine should i support this between the post with just the gravel boards or should i use concrete blocks or patio slabs between the posts??
Any help or info would be appreciatted
Thank you
Mike
Posted: Tue May 10, 2005 10:26 pm
by Tony McC
So: you've 6'6" (in old money) of fence above ground - a 6" gravel board and a 6' panel. Why are you using 10' posts? Do you plan to bury 3'6" or just the 2'6" and have 1' sticking up above the eventual panel?
You're using 5" posts but plan to have a hole 24" wide, allowing for a whopping 19" of concrete to be used to fill the hole. If you have firm ground, all you need is a max of 4" of concrete all round, so that gives you a max hole size of 13" (4"+5"+4") square. Adding lots and lots of concrete does not necessarily make for a stronger fence - it just means more weight, more expense, more work. If the ground is stable and firm, let it support the fence - the concrete is mainly there to fill the gap between post and ground.
Then there's the depth of these pits you're planning to dig. What benefit is gained by digging a 2'6" hole then re-filling part of it with gravel? Gravel won't hold a post in place, and it wont prevent it sinking in. If you really want to dig 2'6" deep, then putting 2-4" of CONCRETE in the base of the hole would help prevent the post settling, but gravel is a waste of time.
For a 6'6" fence we'd normally sink 1'9"-2" of post into the ground. So, the holes need be just 13" square and 2'-2'4" deep. Half a spade of semi-dry 1:3:6 mix concrete in the bottom, then the post. Hold it roughly plumb and backfill the hole with more of the semi-dry, packing it in as you go and checking/adjusting for plumb as you go. Once it's in, and the concrete is within 4" of the top of the hole, use two sticks at right angles to brace this first post.
Gravel board - if your neighbour's land is higher than yours, then a timber gravel board is a waste of time. You should use concrete. But you have timber posts which aren't compatible with concrete gravel boards, so that plan is stuffed. All you can do is set the timber gravel board in place, supported on a couple of broken flag or brick chocks, and screwed/nailed ONCE ONLY to the post. You may need to adjust the level later, so don't be effing about driving in half a pack of screws!
Check gravel board is more or less level (flat) and at the correct level (height-wise) and it gives you the position of the next hole. Dig, base concrete, post, haunch concrete, sprag as required, next gravel board. &c.
It's best to leave out the panels until the following day when the concrete post haunch will have hardened and any wind load will be tolerable. There should be sufficient 'play' between the post to allow you to squeeze in the panels and then fix as necessary. If the ground is exceptionally dry and/or the semi-dry mix is a bit on the dry side, you can splosh a bucket of water over the concrete hole when you're done. As the concrete should be left lower than the top of the hole, the water will just sit there for a few minutes but will soak in and accelerate hydration of the concrete, but, in the vast majority of cases, there's ample moisture in the concrete and the ground to ensure the mix sets.
Leave the sprags in for a couple of days, just to be on the safe side, and that's all there is to it! This is fence erection - it's not a precise science, so don't get overly technical and don't build nuclear-bomb proof posts!
Posted: Wed May 11, 2005 1:12 pm
by Onlyme
Tony,
thank you for the info just a couple of questions re.
It's best to leave out the panels until the following day when the concrete post haunch will have hardened and any wind load will be tolerable. There should be sufficient 'play' between the post to allow you to squeeze in the panels and then fix as necessary.[quote]
My panels are quite heavy being solid T&G, how would you suggest dropping the panels in from the top. Would you use a small scaffold tower to raise above the posts, then with two people lower them in from above. ( the slotted posts have a inch deep slot for the panel to slide into) Do you think the posts will safely flex this much to get the panel in from ground level (at least 2 inchesat the bottom) without the risk of loosening the post.
Thank you
Mike
Posted: Wed May 11, 2005 1:14 pm
by Onlyme
Tony,
thank you for the info just a couple of questions re.
It's best to leave out the panels until the following day when the concrete post haunch will have hardened and any wind load will be tolerable. There should be sufficient 'play' between the post to allow you to squeeze in the panels and then fix as necessary.[quote]
My panels are quite heavy being solid T&G, how would you suggest dropping the panels in from the top. Would you use a small scaffold tower to raise above the posts, then with two people lower them in from above. ( the slotted posts have a inch deep slot for the panel to slide into) Do you think the posts will safely flex this much to get the panel in from ground level (at least 2 inche sat the bottom) without the risk of loosening the post.
Thank you
Mike
Posted: Sun May 29, 2005 1:32 pm
by Tony McC
Probably too late, but the posts need to be lifted in from the top, so some form of lifting gear is advisable. Otherwise, you will need a couple of trestles and a few planks to create an elevated platform to stand on while lifting the panels into place.