Quick question concerning the required length of coach bolts... I'm going to build a deck using 100mm support posts with 47mm joist connected with coach bolts. Question is should I use 150mm coach bolts or longer? Is the 3mm left over ample to tighten the coach bolt?
Sorry if it seems obvious to some just never used coach bolts before.
By the time you add a washer under the nut there'll be a bit less bolt available :-)
Are the post & joist dimensions you quote actual or nominal?
I would rather have a bit of bolt protruding from the nut.
The dimensions are off the order form so nominal... I was thinking the same thing about the protruding bolt
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Even without a washer (you are using washers?) 3 mm seems a little inadequate.
What you need to avoid is an unthreaded shaft length in excess of the thickness to be clamped but if the numbers don't add up you can get coach bolts that have a fully threaded shaft. I would have it that these are technically screws rather than bolts but don't blame me if the vendor doesn't appreciate the difference.
However, you can recess the coach bolts into the wood, and even plug on top of them with cut out circles when you've finished. Just leave enough room for the appropriate socket for the nut to go over it.
Counterbore the post to a depth of 1/2". If you want to be able to dismantle this structure easily, grease (or dip in Waxoyl) the bolts before fitting - they tend to rust in solid.
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