Deck

It depends on if you plan on walking on the deck. If not, one foot would be sufficient.

Re: Deck


You don't have enough info here to provide a simple answer.

There are two rules of thumb to use.

a.) the cantilevered portion should never exceed 40% of the total length of the joists used. If you want 4' cantilevered then, as a minimum, you need 10' long joists with 6' of it anchored into the existing structure and:

b.) The cantilevered portion should never exceed 4x the width of the joists used. For a 4' cantilever you would need to use 2"x12" lumber.

In your case, anything less than 10' long 2"x12" joists (16" on centers) embedded 6' into the existing building would be unsafe.

and remember this.... everyone comes when you have a big deck.....so enjoy.