Thru-Bolt Ledger Connection - Bolt Size?


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Old 10-17-11, 07:26 AM
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Thru-Bolt Ledger Connection - Bolt Size?

I'm attaching a 2x10 pressure treated ledger to my townhome. I have the lower level ceiling torn out, so I can get to the band joist on the inside of the wall. Because of this, I should be able to use a thru-bolt (instead of lag screw or ledgerlok) connection.

Is 3/8" x 5" long hot dipped galvanized the correct type?
 
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Old 10-17-11, 09:15 AM
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I used 1/2" bolts with fender washers. It's been a while but I think that's what was required by code. I used 2 bolts per joist bay and staggered the bolts so that they didn't weaken the ledger. Make sure they are hot dipped galvanized.
 
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Old 10-17-11, 06:25 PM
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One code change here is the fender type washers are required not only on the nut side, but a size larger is required on the carriage bolt head side. Larger size to allow it to sit flat around the shoulders.
 
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Old 10-17-11, 08:14 PM
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If you plan to keep the place a long time, I'd suggest using inert spacers (4" x 4" blocks of Trex work well) between the ledger board and the house's rim board. Otherwise, there's a good chance the contact surface between the two members will eventually rot out, unless carefully-applied flashing and caulking are used to keep water away from that area. You'll need 6" long bolts if you use 1" spacers.

And never use less than 1/2" galvanized bolts for ledger attachment. I suspect the earlier post saying to use 2 bolts per joist space may be a bit more than needed, but check your local building code requirements to make sure. A single mild steel (Grade 307) bolt has a working shear resistance of almost 1 ton (1963 lb.).
 
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Old 10-18-11, 07:15 AM
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1/2" hot dip galvanized or some other fastener certified to work with modern treated lumber is required here. They will not accept 1/2" zinc plated bolts. Hot dip galvanized is the minimum corrosion protection as is 1/2" diameter. Lag bolts/screws are not permitted. They must be through bolts.
 
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Old 10-24-11, 01:43 PM
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Got it. I used 1/2" HDG with washers on both sides.
 
 

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