Pressure Treated Post and Rail Fence Questions


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Old 08-08-16, 11:17 AM
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Pressure Treated Post and Rail Fence Questions

Hello all,

We're in the process of building a 700+ ft long wooden fence using pressure treated SYP. We have most of the posts set, all in concrete and several feet deep. The posts will end up being ~5 ft. tall. We're going to have welded or woven wire and 3 2x6 rails between each post. The rails will be attached using FastenMaster HeadLok 4 1/2 inch screws. I have a few questions:

- The wood was bought from Home Depot, so is obviously quite wet. We've had the rails for a while and have left them bound. I figured this would help them retain their shape before we attach them to the posts. The thought is that it would be best to leave them bound to prevent bowing and then once attached, the fact that they're fastened will help prevent them from bowing too much. Does this make sense or am I off base? We did separate the posts so that they could dry more evenly to prevent bowing of the posts. It seems to have worked pretty well. We've exchanged the posts that bowed too much.

- Should we use two fasteners per side per rail (top and bottom) to affix them to the posts (so 4 fasteners per rail total)? Or just one per each side in the middle? My thought was that 2 fasteners per side (top and bottom) could reduce cupping, but would this increase the likelihood that the rails will split since the screws will be closer to the edge and there will be some shrinkage as the rails dry?

- If any of the rails have already started to cup slightly, should we fasten them with the cupping toward the posts to allow for the force to be working opposite of the cupping?

Thanks for any help anyone can provide! :-)
 
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Old 08-08-16, 11:38 AM
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Did the posts that you set into the ground/concrete specify that they were for Ground Contact applications?
 
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Old 08-08-16, 11:41 AM
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The posts and all the rails are rated for ground contact.
 
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Old 08-08-16, 01:19 PM
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At least with keeping the wood bundled you will be able to get it up before it warps. Whether or not being attached helps limit warping will depend on how badly the wood wants to warp. I have 2x6 and 2x8 flooring in my trailers and I've heard the 1/4" bolts snap as the wood tries to do it's own thing. If there is a piece of wood destined to warp there isn't much you can do to stop it.

I would use four screws, two per end on each board. If you're worried about splitting you can pre-drill the holes and since your screws have nice big heads you could over size the pilot holes to allow for movement.

As far as the cupping direction I've not seen where it really matters. I don't think you'll be able to pull the cupping out and to do so would take so much force that you'll risk stripping screw holes, breaking screws or setting the boards up to split later on.
 
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Old 08-09-16, 12:01 PM
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Lumber

Lumber left bundled will stay wet until you open the bundle.
 
 

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