Replies

1. 
   xMikeSmith | Dec 29, 2003 05:33am | #1

   most decks can not be cantilevered.. in  a lot of locations the code loading is 60 lb/sf

   at that rate you MIGHT be able to cantilever about 2'

   also.. it is almost impossible to cantilever without making numerous penetrations that will leak and rot out the framing.. there is practically no detail that will prevent this

   others may have different opinions... but these are mine.. forget about cantilever

   Mike Smith   Rhode Island : Design / Build / Repair / Restore

2. 
   Davo304 | Dec 29, 2003 10:43am | #2

   "2 for 1 ratio..."

   Generally, rule of thumb is that a cantilever should not exceed 1/3 its total length, so you are correct. ( ie...to cantilever out 6 ft, you need a joist whose total length is 18 ft; of which 12ft will be attached to solid anchoring  and the remaining 6ft will be hanging out...hence 12ft vs 6 ft = 2 to 1 ratio).

   But, for conservative floor loads, it would be better to calculate your cantilever to not exceed 1/4th its total length instead. ( ie... to cantilever 6ft out, use a joist 24 ft long).

   If you plan on cantilevering farther out than 6ft using a 2x10, I'd definately get a structural engineer involved or rethink my deck design altogether ( ie...install a few support posts underneath the joist deck span).

   Davo

1. 
   xMikeSmith | Dec 29, 2003 01:55pm | #4

   davo.. you also have to allow for strength of materials.. ie:  what is the breaking strength of the  2x10... this is usually the limiting value in a deck cantileverMike Smith   Rhode Island : Design / Build / Repair / Restore

3. 
   jlawley | Dec 29, 2003 11:10am | #3

   First, what will the finished elevation of your deck be? It doesn't affect the load calculations but it lets you know how close to max tolerance you want to get. Why not just sink a few posts, it really doesn't take much effort, and using a couple of posts with shorter joists will probably be less expensive than using 24' joists just to get 6' of deck.

4. 
   fredsmart48 | Dec 29, 2003 05:40pm | #5

   What does your building code say for cantilever?   Here for a 2x10 x is 24" of  cantilever alowed.  Also the rin boards are figured into the cantilever length.   2x8 you can have 20 inch of cantilever.

   For a longer cantilever you need to hire a engineer to sign off on the plans.