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Re: Ceiling joists/rafter ties IRC R802.3.1

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I'm sure the numbers don't work, especially with more
complex roof shapes.  I just would like to know what
the code requires for my own edification, and so I
know when to advise a builder if his work doesn't meet
code.

Jim

--- "Jordan Truesdell, PE"
<seaint1(--nospam--at)truesdellengineering.com> wrote:

> Jim,
> 
> This may seem like a cop-out, but what do the
> numbers say?  In a 
> prescriptive design sense, it would seem reasonable
> to require any 
> horizontal thrust be resisted by a defined load
> path, hence the 
> requirement.  Can the load be taken out through
> another means? For 
> example, is the ceiling joist below where the hip
> rafters meet the ridge 
> strong enough (including connections) to support the
> hip rafter as a 
> structural beam (and is the hip designed
> structural)?  If not, can it be 
> beefed up to support the load?  If not, then I'd say
> the tension ties 
> are technically necessary.  Will the building fall
> down if you don't? 
> Probably not soon. Since you've got a ceiling, the
> gwb will support some 
> tension at the hip-jack ends, and transfer the force
> to the side walls 
> via shear.  It depends on whether the gwb is strong
> enough under a full 
> code load and whether you are comfortable using is
> as a primary 
> structural path.
> 
> Jordan
> 
> Jim Wilson wrote:
> 
> >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
> >
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