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Re: FW: Ceiling joists/rafter ties IRC R802.3.1

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Title: Re: FW: Ceiling joists/rafter ties IRC R802.3.1

The Wood Frame Construction Manual (WFCM) provides diaphragm capacities for gypsum sheathing (WFCM Supplement Table 2C) of 70 plf.

Another publication on our website, Details for Conventional Wood Frame Construction shows a detail in Figure 52 that might be helpful.

There's been no testing that I'm aware of.



From: Jim Wilson <wilsonengineers(--nospam--at)>
Subject: Re: FW: Ceiling joists/rafter ties IRC R802.3.1
To: seaint(--nospam--at)
That helps a lot considering it comes from the
"source." As Jordan alluded to, are there any
acceptable means of tieing roofs by means other than a
double layer of rafter tie? I.e., gypsum drywall,
diagonal struts, wall top plates in strong axis
bending, etc. And by acceptable, I mean by the code
or by testing and development of prescriptive-type
Thanks for the info!
Jim Wilson
--- AWC Info <AWCInfo(--nospam--at)> wrote:
> If it is a hip-beam system, there is no thrust... So
> it only needs to be
> tied together to resist out-of-plane wind loads...
> Analogous to a ridge beam
> system.
> If it is a hip rafter system (conventional
> construction), it needs to be
> tied together in both directions because the hip
> rafter is just a connection
> point... Analogous to a ridge board system.
> Buddy
> John "Buddy" Showalter, P.E.
> Director, Technical Media
> AF&PA/American Wood Council
> 1111 19th Street, NW, Suite 800
> Washington, DC 20036
> P: 202-463-2769
> F: 202-463-2791
> The American Wood Council (AWC) is the wood products
> division of the
> American Forest & Paper Association (AF&PA). AWC
> develops internationally
> recognized standards for wood design and
> construction. Its efforts with
> building codes and standards, engineering and
> research, and technology
> transfer ensure proper application for engineered
> and traditional wood
> products.
> *********************
> The guidance provided herein is not a formal
> interpretation of any AF&PA
> standard. Interpretations of AF&PA standards are
> only available through a
> formal process outlined in AF&PA's standards
> development procedures.
> *********************
> >
> > From: Jim Wilson <wilsonengineers(--nospam--at)>
> > Subject: Ceiling joists/rafter ties IRC R802.3.1
> > To: seaint(--nospam--at)
> > IRC R802.3.1 Ceiling Joist and rafter connections:
> >
> > "Where ceiling joists are not parallel to rafters,
> subflooring or
> > metal straps attached to the ends of the rafters
> shall be installed in
> > a manner to provide a continuous tie across the
> building, or rafters
> > shall be tied to 1-inch by 4-inch minimum-size
> crossties."
> >
> > Does this apply to the secondary direction in a
> > hip-framed roof? Some inspectors insist so, some
> > don't know, some don't know that they don't know.
> >
> > I've never seen it applied this way in the field,
> but
> > one prominent local builder has been specifying
> > two-way ties on their hip-roof structures. I would
> > like to either back them up, or save them the
> effort
> > and the consumer the added cost and inconvenience.
> >
> > Thanks in advance.
> >
> > Jim Wilson, PE
> > Stroudsburg, PA