Floor Joist Cantilever Design

Cantilevered joists in an enclosed space.

Floor joist cantilever design. A full depth rim joist shall be provided at the unsupported end of the cantilever joists. Cantilevered floor joists 1 floor joists supporting roof loads shall not be cantilevered more than 400 mm beyond their supports where 38 mm by 184 mm joists are used and not more than 600 mm beyond their supports where 38 mm by 235 mm or larger joists are used. Instead of separate tables for non cantilevered and cantilevered joists a single proposed table provides maximum joist span and cantilever distances for all conditions which should simplify joist specification without compromising design freedom. The distance your joists can safely cantilever or overhang a drop beam is determined by the size of the joists the wood type and grade of the lumber and the spacing between joists.

Many building departments limit joist cantilevers to 24 maximum. Cantilevered floor joists h1 2 treated l. Element in the storey below in which case blocking is required by clause 7 1 2 1 of nzs 3604 2011 and figure 7 2. Similar to joists beams can cantilever up to one fourth their backspan.

Cantilevers parallel to joist direction in this situation while the open web joist stops at an exterior bearing a 2x extension from it extends beyond the bearing to become the cantilever joist. Design software will dictate specific framing practices but for our purposes here general approaches to cantilever installation will be discussed. See section r301 2 2 2 5 item 1 for additional limitations on cantilevered floor joists for detached one and two family dwellings in seismic design category d 0 d 1 or d 2 and townhouses in seismic design category c d 0 d 1 or d 2. You must use at least five framing nails to attach the rim joist to the ends of your joists.

The ontario building code cantilevered floor joists 9 23 9 9.