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RE: Cantilevers through a solid beam

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Roger,
It will always boil down to suggestion 4. No matter how I design it, the
framer will want to do it his way. Inasmuch as there is little shear to
transfer and the only real concern is uplift (assuming the roof sheathing is
continuous over the beam) I am not concerned for other than architectural
appearance.
I'm beginning to think that if the architect keeps limiting me with these
types of problems - and they are not really structural issues - I'll leave
them to him and the framer. Sooner or later he is going to understand that a
12" beam is not going to work for a 22 foot span in most cases. Funny how
Architects simply show what fits the sections rather than what will
realistically work in any given situation.

Dennis

-----Original Message-----
From: Roger Turk [mailto:73527.1356(--nospam--at)compuserve.com]
Sent: Tuesday, February 02, 1999 2:20 PM
To: seaint(--nospam--at)seaint.org
Subject: Cantilevers through a solid beam


Dennis,

As I understand it, you need to extend the roof 16" beyond a 16" deep
Parallam beam and support a parapet at the end of the roof extension.  That
means that the facia at the face of the parapet is going to be greater than
16", so I don't see where that is a limitation.

Suggestion No. 1:  Connect the rafter to the Parallam with a strap over and
nailed to the back side of the Parallam and support the end with a "kicker"
running from the bottom of the Parallam to the end of the rafter.

Suggestion No. 2:  Same as suggestion no. 1, except tie the rafter to the
Parallam with a Simpson LTT (or similar).

Suggestion No. 3:  Run a diagonal member from the top of the Parallam to the
top of the parapet, a horizontal member from on top of the Parallam to the
parapet, and a diagonal "kicker" from the bottom of the Parallam to the end
of the horizontal member.

Suggestion No. 4:  Ask a carpenter how it will be framed.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

. > I have a design problem where I need to build out the face of a patio
from
. > the supporting beams by 16" - and add a parapet above this. The problem
is
. > that the total depth of the beam and roof framing is limited to 16
inches
. > - which happens to be the size of the Parallam required for a 24'-0"
. > span. The back-span of the rafters is less than 15 feet and the
. > cantilever is suppose to be, as I mentioned, 16 inches.
. >
. > An idea came to me that I wanted to run by this group.
. >
. > I need to extend at least a 2x4" member over the beam - which is not
. > possible because of the restricted depth. Since this is the compression
. > side of the beam, I thought that I might be able to notch out the 2x4 in
. > the top side of the Parallam (3.5" depth) and extend the 2x4's through
the
. > beam. When loaded, the beam will be in compression and the bottom of the
. > rafter is above the neutral axis so that it remains in compression. I
can
. > strap this to compensate for a possible uplift by wind or seismic that
. > might place the upper side of the beam in tension.
. >
. > Any thoughts on this?
. > Any better suggestions?
. >
. > Thanks,
. > Dennis Wish PE
. >