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Im building a 3 season porch. Whats the best way to attach a ledger board to a masonry block foundation wall. Thanks.
Dave
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I was primitive and used through-bolts with plywood inside, but I did so because it was old brick of uncertain stability. I've noticed recently that CMU's vary widely in their strength. If the ledger's pullout strength is important to you, I don't know how trustworthy lag shields would be. Sooo... solid grouted blocks? Hmm, I'm just thinking out loud, this has been on my mind....
Not to offend Creature, but may I add a related Q: Ledger to TJI band joist w/o blocking? (how?) I -think- it's a TJI, I got nothing but insulation test-drilling between the plates ... haven't drilled deeper yet to find the web i suspect is there ... I can't get behind whatever it is to block, it's a second-floor deck. Plan I have is to mount the ledger low and lag screw into the first floor wall and plates, place deck joists on top.
Yet, I notice the builder put in lots of decks all over the development with flush ledgers. I can't imagine what they are bolted to, the 2x6 ledgers aren't wide enough to reach both flanges of the TJI, if bolting to the flange is even OK (?). Does he know something I don't? Maybe the builder's not the best, I noticed there wasn't any wrap between the vinyl siding and OSB, for example.
*Creature,I still prefer to use large Tapcon screws at every 16 inches minimum. Just put the ledger board against the masonry wall and screw like it's your wedding nite.Gabe
*I through bolt with those big square washers on the inside so there isn't too much stress concentration at the bolts. Use the same washers on the outside so the bolt doesn sink into the ledger in a year or so.
*TAPCONs, Gabe? Are you jesting? I'm a big Tapcon fan, but I wonder about the shear and tensile strengh in this application. Perhaps I'm biased by our local requirements for 1/2" machine bolt through-bolting 16" O.C. I like the idea of a backer board in addition to the big washers.Respectfully, Steve
*Hi Steve,Creature posted a question without any other information regarding size, foundations if any, loading, construction methods to be used, etc.On some applications, that both of us have seen, 3/4" bolts would be insufficient.For the other 90% of the applications, ledgers carry minimal weight loads. The walls are attached to the existing building, the roof is attached to the existing building and the floor joist rest on beams over concrete pads or columns.Yes Steve tapcons would do the job. Screw a 2x12 with tapcons to a masonry wall @ 16" spacing, top and bottom and then try to lift it up with a hydraulic jack and watch your house go up.There's a size for every job. Next time you walk into a large commercial building with 12" steel piping and such suspended above your head, chances are they are being held up by tapcons.Gabe
*Through-bolt. 5/8" HD galvanized. Any wood that is in contact with masonry is PT.
*Gabe makes the good point that the size of the fasteners is an engineering question. The Tapcons do have high shear ratings, the 1/4" ones I have on the desk here are rated 1058 lbs. with 1 1/4" embedment in "lightweight hollow block." Pullout is about half that. Simpson 2x8 joist hangers are only rated for about 1000 lbs. Food for thought.... I still like bolts. :)
*Just so nobody is left in suspense....heres what Im going to do. Im going to Tapcon the ledger to the wall then through bolt it as well. Overkill?? Maybe. But a call back isnt worth the hassle. Hey, everybodys happy. Thanks for the advice.Dave
*Nice response, Gabe... I imagined (from a current project) a 2x10 ledger with 12' 2x10 joists on hangers, then ceramic tile over a 1" mud floor on 3/4" Advantech: Lots of dead load. No beams, piers or pilasters... just a simple ledger mounted to the CMU wall. Also, the Tapcons I'm familiar with are kind of wimpy: 1/4" x 2-3/4" being the largest I've used.Regards, Steve
*Some call things like that overkill...I call them insurance! And I still don't think Tapcons alone are up to code. Jeff
*Jeff:I take back the part about overkill. If you run the numbers on my particular porch deck the Tapcons satisfy the shear requirements but not pull-out. The Tapcon is OK but the block can't take the load. SO yes, its very good insurance!! I'll be using the Tapcons to temporarily hold the ledger in place while I drill for my bolt holes.Dave