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MikeB4:
Our fences all have carriage bolts right through the rail and post using bolts and washers like these, but galvanised not chrome like the pics. That would have prevented the post from warping and pulling away. I would say all your posts and rails are at risk
My recent fence also has these installed. I would think this would make it very difficult for the post to come apart from the railings, so that should help to keep it straight.
mattwnz:
My recent fence also has these installed. I would think this would make it very difficult for the post to come apart from the railings, so that should help to keep it straight.
In my case the tech screws didn't get pulled out of the post, rather the shearing force of the post warping parallel to the fence actually snapped the screws. If the post had only warped outward from the fence it wouldn't have come away from the railing as the screws wouldn't have snapped. But I have no doubt that had the screws held that it would have just pulled the fence out of line, the fence wouldn't have kept the post straight.
jonathan18: So they used both the standard round washers and the square ones? And in which order? I saw them when I was getting a quote for fence things yesterday, but wasn’t sure if they were advisable. Would they be useful if only attaching the rails to concrete posts?
In relation to bolts, why select those with the round head (as above) as opposed to those with hex heads?
Similarly, Bunning’s has boots designed specifically for treated pine, which the guy there recommended over galvanised due to those leaching into the wood (or something like that). I’d be using these but for the limited range of lengths, ie 150 and 200 mm, whereas I’m after somewhere in the middle!
Thanks for any advice.
How long a fence are you doing, and is it street facing?
I've been glancing at peoples fences over the weekend, and there aren't a lot of straight ones!
I wouldn't do it for up the driveway or property boundary, but for a nice looking street facing fence (not just you basic overlapping paling job) I'd see if the budget could stretch to laminated posts.
Bung:clevedon:
Bung: The post is bowing toward the side that's drying fastest. I'd try soaking the outside of the post (opposite the rail side)and see if it starts to straighten.
Hahaha, that's the funniest thing I've read in a long time.
Given time to dry evenly the post may stay straight. I've had posts lying on the ground bend back and forth depending on which side was down.
We have a couple of timber field gates made by the old fella (now deceased) who used to put sheep on our place. The gates look fine, but the timber is absolute ess aitch one tee. They warp so much you have to lean on them sometimes to do up the chain and then when the weather changes, they will be straight as a die again! If I could work out what causes the bend and what causes the straightening, I could use them as a barometer.
32m fence, between the neighbour's place and ours.
I'm not even thinking of replacing the concrete posts! They're fairly straight and in good condition (even if there's no even spacing between them), and there's also a full concrete strip running the length of the fence (which means we can avoid having the palings sitting near the soil).
Luckily, we've got all the palings on our side (well, what's left of them! Many have rotted and so we've had to remove them), so replicating that means we'll continue to have that.
The neighbour's agreed to pay for the supplies and we'll build it. So I want to make sure we do it properly, hence my questions about which are the most appropriate bolts to use (those in the image above, or a hex head) and whether I should use those square washers or not.
jonathan18:
32m fence, between the neighbour's place and ours.
I'm not even thinking of replacing the concrete posts! They're fairly straight and in good condition (even if there's no even spacing between them), and there's also a full concrete strip running the length of the fence (which means we can avoid having the palings sitting near the soil).
Luckily, we've got all the palings on our side (well, what's left of them! Many have rotted and so we've had to remove them), so replicating that means we'll continue to have that.
The neighbour's agreed to pay for the supplies and we'll build it. So I want to make sure we do it properly, hence my questions about which are the most appropriate bolts to use (those in the image above, or a hex head) and whether I should use those square washers or not.
The bolts in the picture above are 'coach bolts'
The square section under the round head pulls into the wood as the bolt is tightened - until the flat surface of the head (or the the carriage bolt washer if more area is required) presses into the wood 'locking' it in place and presenting an almost flush surface.
A hex nut with a large washer is used on the other end, the washer again providing surface area to distribute the load of the tensioned bolt over the surface of the wood.
Edit: To answer your question - you can use either round or square washers at the nut end, coach bolts cost more, and require pre-drilling but provide both higher tensile strength and greater shear resistance than construction screws
If building a fence, you can bolt railings and posts together as securely as you like. If the posts bends it will simply pull or push the railing out of line. The simplest option is to not buy low quality timber in the first place - find timber yard that will sell you straight grained timber.
If I was a building fence, I would spend the extra coin and use H4 laminated posts. Do once, do right.
Mike
Sidestep:
The bolts in the picture above are 'coach bolts'
The square section under the round head pulls into the wood as the bolt is tightened - until the flat surface of the head (or the the carriage bolt washer if more area is required) presses into the wood 'locking' it in place and presenting an almost flush surface.
A hex nut with a large washer is used on the other end, the washer again providing surface area to distribute the load of the tensioned bolt over the surface of the wood.
Thanks for that most useful explanation! I have read some fence-building instructions that recommending not using coach bolts as they 'pull in to the timber too much', so I think I'll stick with my plans to use hex-head bolts.
Hopefully someone's able to also help with three more related questions:
Thanks so much.
jonathan18:
I'm thinking of counter-sinking slightly into the rail so as to ensure the hex end sits flush, but also using a standard round washer within the countersunk area to spread the load - does that sound like an ok plan?
And what sort of washer should I use in front of the nut? - Given that'll be sitting against the concrete of the posts I wonder if one of those standard round ones would be ok, or should I be using the 50x50x3mm square ones?
Finally, how critical is it to be using the 'tech-shield' bolts and washers as opposed to standard galvanised? They claim 'up to 4 times the protection of Galvanised in treated pine', and the price is fine - it's just that, at 200mm, they're going to jut out a decent amount (posts 110mm, rails 50mm).
Countersinking the nut, and a decent sized washer will take extra time - but look good - as long as it's not countersunk so deeply it reduces the rail's strength.
Given concrete's compressive strength the washer against the concrete post just needs to be large enough to prevent the head of the bolt pulling through the hole.
I used galvanised coach bolts, through treated wood, to construct a large deck which I partly dismantled after 20 years use. There was discoloration of the zinc but the bolts were in good enough condition they could have been re-used. In permanently damp, ground-contact conditions that might have been different, but on a fence galv bolts should do.
Sidestep:
In permanently damp, ground-contact conditions that might have been different, but on a fence galv bolts should do.
Galv bolts are used on wharves, yet are considered unsuitable for balconies in a coastal zone.
Mike
Thanks for all the useful answers; sounds like galvanised hardware's fine, so will stick with that.
Last question promise!
If I wasn't to countersink the bolt heads, what other way would I ensure that I can place a paling over top of the part of the rail where the bolt head does poke out? I'm wanting to have palings with no gaps at all, including where they are in front of a rail - this is how the fence is currently built. Would I need to drill out the back of a paling to provide for the bolt? Sorry if this doesn't make sense...
jonathan18:
Thanks for all the useful answers; sounds like galvanised hardware's fine, so will stick with that.
Last question promise!
If I wasn't to countersink the bolt heads, what other way would I ensure that I can place a paling over top of the part of the rail where the bolt head does poke out? I'm wanting to have palings with no gaps at all, including where they are in front of a rail - this is how the fence is currently built. Would I need to drill out the back of a paling to provide for the bolt? Sorry if this doesn't make sense...
Yes drilling a hole in the back of the paling would work too, however be aware that with the reduced thickness of the paling (compared to the post) you will probably need a flat bottomed large diameter drill bit (e.g. forstner bit) - using a auger or spade bit will likely poke a small hole through the front of the paling.
Easiest would be to countersink into the post - say 30mm augur 8mm deep, then your 12mm hole the whole way through. It's a 90mm post, so heaps of stregnth left
jonathan18:
Thanks for all the useful answers; sounds like galvanised hardware's fine, so will stick with that.
Last question promise!
If I wasn't to countersink the bolt heads, what other way would I ensure that I can place a paling over top of the part of the rail where the bolt head does poke out? I'm wanting to have palings with no gaps at all, including where they are in front of a rail - this is how the fence is currently built. Would I need to drill out the back of a paling to provide for the bolt? Sorry if this doesn't make sense...
This is where your coach bolts are useful.
Pop them through, tension them up until they start to pull into the rail, attach palings over the top (if any are still standing proud enough to hold the paling off just belt the paling right over the bolt head to indent it..)
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