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Carriage Bolts & Wood to Wood Connections for Decks

jar546

jar546

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We all know that the AF&PA's NDS does not recognize Carriage Bolts as an acceptable method because the ANSI standard for carriage bolts is not listed in the NDS.

Is there anyone out there whose AHJ allows the use of carriage bolts for wood to wood connections on decks?
 
mark handler said:
It goes both waysfairfax county VA

Carriage-bolts may be substituted where through-bolts are specified provided carriage-bolt washers (with square holes) are installed at the bolt head. Bolts should be tightened six to 12 months after construction due to drying and wood shrinkage.

http://www.fairfaxcounty.gov/dpwes/publications/decks/details.pdf

Montgomery County

Carriage Bolts- NOT acceptable to use

http://permittingservices.montgomerycountymd.gov/DPS/pdf/MCResidentialDeckDetails.pdf
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Interesting take by Fairfax, VA since the AF&PA is located in VA and the NDS does not recognize carriage bolts as acceptable.

Which makes me wonder why the would approve the use of a product not approved in the codes and then place a retightening disclaimer on top of it.

It almost sounds politically motivated.
 
jar:

I'm not sure it's accurate to say that carriage bolts are not allowed by the NDS. Section 11.1.7 of the 2005 standard discusses other types of dowel fasteners. One then has to apply the provisions of 11.3 to design the connection. I've seen numerous connections designed by engineers using carriage bolts and threaded rod. Since most bolted connections are loaded in shear the head configuration is not as critical as it might seem. The hardest part is ensuring that the bolts used have the strength properties that the design calls for. There's a lot of very low quality fasteners out there.

Regards, DB

NB: I haven't seen the 2012 NDS so I don't know if anything has changed.
 
small wonder, I guess, why in DC we get so many calls from builders... most of them also build in Fairfax and/or Montgomery County... two worlds separated by the Potomac.
 
Dbronson said:
jar:I'm not sure it's accurate to say that carriage bolts are not allowed by the NDS. Section 11.1.7 of the 2005 standard discusses other types of dowel fasteners. One then has to apply the provisions of 11.3 to design the connection. I've seen numerous connections designed by engineers using carriage bolts and threaded rod. Since most bolted connections are loaded in shear the head configuration is not as critical as it might seem. The hardest part is ensuring that the bolts used have the strength properties that the design calls for. There's a lot of very low quality fasteners out there.

Regards, DB

NB: I haven't seen the 2012 NDS so I don't know if anything has changed.
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please see Mark Handler's post above for specific info on this topic. This is good stuff,
 
rogerpa said:
Is the documents author, Jim Mailey, Simpson's Jim Mailey?
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Probably is but just in case you are possibly eluding to the fact that he is biased, (I may be assuming) let me kindly interject.

He is not saying that you can't use machine bolts or lag screws either. He is specific to carriage bolts only and is not pushing a Simpson product. The fact remains that the NDS still does not recognize carriage bolts for wood to wood connections.
 
I have always specified and used carriage bolts; Why? Because very simply they work, really really well.

and because several idiots several years ago drove home the listed tested properly documentd LAG Screws straight into the vertical supports of wood floor trusses (change from plan) using and impact wrench and the wanted me to certify that 2 lag screws jack hammered through vertical truss bearing was just as good as the properly spaced lag screws I had specified... The next day after I told them No! and BTW contact the truss fabricator to design the fix for the split bearing elements; I changed all my details to through / carriage bolts so that the process now involved DRILLING. On a better note the deck I replaced on my home last year I used the newer Fastenmaster Thru-Lok; my new favorite toy for securing things that need to stay together ThruLOK® Screw Bolt Fastening System - FastenMaster
 
In my opinion carriage bolts are allowed if designed by a RDP. Following the prescriptive requirements of the code they are not.

R502.6 Bearing. The ends of each joist, beam or girder shall have not less than 1.5 inches (38 mm) of bearing on wood or metal and not less than 3 inches (76 mm) on masonry or concrete except where supported on a 1-inch-by-4-inch (25.4 mm by 102 mm) ribbon strip and nailed to the adjacent stud or by the use of approved joist hangers.

for a 1-1/2" bearing on metal would require a really big carriage bolt .....
 
I want to toss this into the mix! Is the lateral load device not in reality a carriage bolt? or a pieces of tread rod?

Has not the argument always been that because of the threads running the full length of the bolt been the reason why the bolt would fail?

What say you?
 
Why fight it? A proper machine bolt with a bridge(malleable) washer looks 10 times better, a hole needs to be drilled anyway and the product looks better.

Brent
 
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