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Cantilever directly from ledger board

dbugg's picture

Hi everybody. We are covering an old concrete landing and concrete stairs with decking. We would like to have an overhang on one side of the landing. The cantilever distance would be 2'. The current plan is to attach a ledger board to the concrete in that section, and then joist to that with joist hangers. I've looked at the codes and the cantilever discussion does not cover this application, since really the entire "span" of the joists (2') would be from the ledger board. Any help?  

db (post #216634, reply #1 of 2)

 

dbugg wrote:

Hi everybody. We are covering an old concrete landing and concrete stairs with decking. We would like to have an overhang on one side of the landing. The cantilever distance would be 2'. The current plan is to attach a ledger board to the concrete in that section, and then joist to that with joist hangers. I've looked at the codes and the cantilever discussion does not cover this application, since really the entire "span" of the joists (2') would be from the ledger board. Any help?  

If I understand your description.

Think of this as a 2ft deep shelf bolted to the wall that should hold over 300+ lbs of books.  Would you do that ?

You might be able to do what you propose welding up a couple of steel triangular brackets with long legs and securely bolting them to the side of your landing........

maybe.

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I'm not sure I understand the (post #216634, reply #2 of 2)

I'm not sure I understand the situation you describe. A cantilever implies a fulcrum; a balance point so to speak. A cantelever implies a fastening point some distance from the edge of the concrete (the fulcrum). Beyond the fulcrum the force is down. At the fastening point the force is up.In short,  you cannot bolt a ledger to the edge of the stoop and then add floor joist!!  If you do so the upward and downward forces will be telescoped to the decking boards (usually 5/4 x 6 material). Make sense?

If I have understood your correctly, your floor joists must run on top of the stoop. They are fastened to a ledger which, in turn, is fastened to the house wall. Now you can cantelever the floor joists beyond the stoop. As a rule-of-thumb I don't cant more than 24". The amount of cantelever depends on floor joist depth and spacing. The 1/3 (cantilever) and 2/3 (back set) rule may or may not apply.

There is one other consideration. Covering your stoop/stairs essentially makes this a deck. The IRC building code has very specific, detailed, and complex requirements for attaching a deck to a house. However, if you do this project as a "free-standing deck", the IRC requirement is much simpler. 

Mel Fros froscarpentry.com