Carriage bolts?

Can carriage bolts be used as deck fastener? To replace lags or trough bolts?

Carriage bolts are usually “through bolts.” If you are referring to beam to post connections, beams must be full bearing on the posts, not just attached by fasteners.

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Need to be more specific as to location and other conditions.
A quality photo would help.

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A carriage bolt is a thru bolt. A common issue I see with deck is the not using the proper flat washer which keeps the square section of the shank from seating properly.
image

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It would take a real genius to put a flat washer on the shank of a carriage bolt. Just saying :roll_eyes:.

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I prefer a through bolt with a hex head. However, they do have washers for carriage bolts (square hole washers) or larger diameter hole washers. Code defines the need for a washer, so I think they just put anything they can find, hence the issues.

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I’ve seen the washers before, but never used them. After all, The whole point of the square shank is to keep it from spinning as it seats. Is that a GA thing to put a washer on it?

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It is a code thing here in GA. So they try to accommodate code and screw it up. (the square shank will still seat, just not as deep because of the thickness of the washer)

I know the picture is bad, but this is from today and there they are…all carriage bolts with washers.
image

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That does not apply to wood. In fact, carriage bolts are not even designed to be installed in wood, thus that problem when used in it. They are designed for metal plate with the square recess. Wood requires Lag bolts or Hex head bolts with washers. Contractors use carriage bolts because they’re cheaper and prettier!

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Interesting. Learned something new. Never seen that before.

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That just reminded me that I have used the square hole washers before. I would weld them to screen clamps on a rock crusher shaker deck. The vibrations would make the bolts work loose and waller out the holes.

JJ, if a hole is drilled 1/32 smaller than the shank of a carriage bolt, it will seat properly and hold for a long time. Coating the bolt with dish soap will aid in getting the bolt through the wood without splitting it. An old timer showed me that back in the 90s. Works pretty good. LOL.

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Oh, I never said it couldn’t be done, just that they were not designed for the task at hand. As for Brian’s post on GA requiring the washer, it is because the carriage bolt head will be over-tightened and dig into the wood cutting the wood grain fibers as it digs in. I know you’ve seen this scenario in person and always assumed it was ok. It technically isn’t.

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Yeah, that does mess things up. Especially if the wood is really dry. Splinter City…

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Which leads to loosening of the bolt/nut and eventual failure if not discovered and corrected… properly.

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Welcome to ur forum, Brandon!..Enjoy and participate. :grinning_face_with_smiling_eyes:

If you use these, you don’t have to worry about a square peg in a round hole.

Timber Bolts

Galvanized timber bolts are sometimes called mushroom head bolts, or dome head bolts. Timber bolts are most commonly used in outdoor wood construction, and can be used in marine applications and treated lumber. The underside of the rounded head has four fins which prevent the bolt from turning in the timber. The oversized head eliminates the need for a washer on the bolt head end.

Select a Diameter

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This

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