Expert: Bruce E. Johnson - 5/28/2009

Question
I want to build a 10x16 patio cover over an existing brick patio. The wall I need to attach the ledger to has a 2 foot cantilever. I know you can't attach a deck ledger to a cantilevered wall but what about a patio cover?

As I understand it, the reason behind not allowing a deck to be hung from a cantilever is twofold: 1 - the house rim joist is effectively "floating" and by attaching the deck ledger to it, you're relying solely on the shear strength of the rim joist nails to bear the weight of the deck. 2 - a deck has a potentially significant live load and the cantilever may not be able to bear this additional weight.  

Both of these make sense to me for a deck but neither would seem to apply for a patio cover (much smaller live load and not attaching to the house rim). Whaddya think?

Thanks,

- Josh  

Answer
Hi Josh, when you say the "wall" you want to attach to has a "cantilever" doesn't make sense to me, sorry.  Are you talking about attaching the ledger to a rafter overhang? I personally wouldn't hang a roof on an overhanging rafter.  You can cut the overhanging rafters back to the wall and then hang your ledger off the cut rafter tails.  You can attach your ledger to the wall beneath the overhang (recommended) if it gives you enough headroom.  You can remove the existing fascia board that caps the ends of your rafters and then run your new rafters past the overhanging rafter tails to get a few more inches of height.  But hanging your patio roof from the rafter tails may eventually cause the rafter tails to sag, break and harm your house roof system.  I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com