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Re: SIP top plate detail

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Joe,

What you are describing is a typical detail for SIP construction.  You can
do it without the bearing plate on top of the let-in (i.e. the second
bearing plate that you refer to) is the load is light enough or you can do
it with the bearing plate.  Keep in mind that the skins of the SIP are
taking the load, so if you do just a let-in (what you refer to a single
bearing plate) then that piece of 2x lumber is not really doing much as a
bearing plate.  The load is basically going directly into the interior
skin from the hanger and your capacity is governed largely by the the
ability of the OSB (SIP are generally made with OSB _NOT_ plywood...unless
it is a "small" SIP operation...one can get OSB sheets in 8 ft x 24 ft,
which means one can make 8 ft x 24 ft SIPs...while you can typically only
get plywood in 4ft x 8ft sheets) to resist being crushed under the hanger
load.  The SIP skin should have no problem resisting 370# of concentrated
load, but you should check with the SIP manufacturer.  In general,
addition a bearing plate (i.e. your second bearing plate) is a good idea
as it helps spread the load to both skins a little more (you will still
have most load going to the interior skin unless you can get the load
applied concentrically).  In the case of a bearing plate, it is not
"overhanging" anything as such plates are usually ripped to the with of
the SIP panel and thus bear directly on the skins.

I can point you to one of our details that shows a similar condition
(actually a floor joist hung off of a wall) if you want...but as I don't
know if you have a SIP supplier/manufacturer on the job or not, I don't
want to step on anyone's toes.

Feel free to contact me if you have additional questions.

Scott
Adrian, MI


On Fri, 3 Feb 2006, Joe Grill wrote:

> I am trying to put together a detail on a project using SIP (“structural
> insulated panels”) those pesky things with a foam core and plywood skins.  I
> have joists framing into the SIP wall from both sides, but at different
> elevations.  The roof slopes on either side of the wall are different and
> are parallel to the wall length.  I was initially thinking about just
> hanging the lower joist off the side of the panel with a top flange joist
> hanger.  In that detail the hanger would be set out from the 2x top plate ˝”
> due to the plywood skin.  I called Simpson to see what they thought about
> that, but have not yet received a reply.  Basically, the top flange of the
> hanger would be on the 2x plate and a portion, ˝”, would be on the plywood
> skin.  I then thought that maybe I could use 2 plates where the top plate
> would be ˝” wider than the bottom, therefore the joist hanger would be
> hanging at the edge of the plate which would be flush with the plywood skin.
> But, there would be, possibly, a ˝” cantilever of the top plate, but on the
> other hand may possibly be supported by the ˝” plywood skin below.  This
> option seems workable, assuming the plywood skin will support the ˝”
> overhanging plate.  Am I missing something, or does anyone think that the
> detail is o.k.  I seem to recall (I think it was Bill Allen) some time back
> that was looking at a detail with a similare overhanging plate, but if I
> remember correctly, there was no plywood skin present, or maybe there was.
> Is a ˝” cantilever at the top plate no big deal if we consider that the
> plywood skin will not support the edge of the top plate?  The reaction on
> the joist hanger is about 370# of which about 60% is snow load.
>
>
>
> Any ideas?
>
>
>
> Thanks,
>
> Joe Grill
>
>
>
> Joseph R. Grill, P.E. (Structural)
>
> Shephard - Wesnitzer, Inc.
>
> Civil Engineering and Surveying
>
> P.O. Box 3924
>
> Sedona, AZ  86340
>
> PHONE (928) 282-1061
>
> FAX (928) 282-2058
>
> jgrill(--nospam--at)swiaz.com
>
>
>
>  <http://inet/index.htm>
>
>
>
>

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