Cantilever (with shed roof)

[mparker]

Hi, a question about IRC 2003 ();
From the way I read it, you CAN cantilever up to about 24" AND have yoiur shed-style roof posts be at the end of the cantilever IF

-it is 'lighly-framed'
-your joists are at least 2x8 and at least 16 oc.

I'm asking as I'm building a porch over a concrete slab; the slab is 61" d x 111" w, and I'm extending 128" on either side, plus extending out to 70" depth. The whole porch will then be about 32' x ~6' ft.

On top, I'll have a shed-style roof thtat is 6/12 pitch, stick-built, with 6 4x4 turned posts. The roof will be about 32' x ~6'.

Soooooo....
-can I place the posts near the end of the joists, maybe about 8" from my support beam?? My beam is about 55" from the house wall.
-for the shed-style roof, what size wood for the beam?? I was thinking doubled-up 2x8, and PT
-for the roof beam, kiln-dried instead of PT??

Thanks for any input!

[Richard A Hetzel]

The posts have to be directly under the beam.

Your architect can advise you as to beam size and material.

[mparker]

sorry should have been more clear;
the ROOF support posts, not the BEAM supports. I'd like to shift the roof supports out by a little less than a foot.

[Richard A Hetzel]

Doesn't the beam support the roof? ALL the supports are beam supports was well as roof supports, unless I'm not seeing something.

[mparker]

pictures would work better, but I think my terminology is lacking, too.

here is my framing, from the ground up:
-frost footer
-support posts for joist support beam
-joist support beam (parallel to the house wall)
-joists (cantivlered 18" out of 72"), perpendicular to house wall
-floor
-roof support posts (rest on pliths, floor, blocking)
-roof beam (2 2x6 or 2 2x8)
-roof rafters (2x4)

what I'm looking to do is tweak the 'roof support posts' towards the joist ends a little less than a foot, realizing that it will create some moment loading on the attached end of the cantivered joists. It will only be for a 12' secion of roof, in essence, because of the 111" slab in the middle.

[Richard A Hetzel]

Well, the roof beam would cantilever beyond the "tweaked" posts, wouldn't it, and in doing so, support those end joists?