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Wayne Whitney Wayne Whitney is offline
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Default Roofing Question

On 2008-04-07, RicodJour wrote:

On Apr 7, 12:09 am, Wayne Whitney wrote:

It's not a matter of ripping off the T&G boards, it's a matter of
deforming the framing so that each rectangle formed by two joists and
two of the T&G boards becomes a non-rectangular quadrilateral.

It's safe to assume that the guy's framing DD's house didn't use 32"
long scrap to sheath the roof, so it's not just two _rafters_
involved, probably more like five or six or more.

Right, I was referring to the whole system deforming, so that "each"
rectangle deforms, together.

At the forces required to make a, what?, 30' roof start to rack
appreciably, the whole roof would come off in a piece. Other
failure modes would be involved way before roof racking became an

The longer the ridge is, the lower the resistance to lateral forces
will be. As for uplift, that's a great point--increase the racking
resistance enough and you can be sure that the uplift failure mode
will dominate. So _if_ the OP is in a high wind or seismic area, and
_if_ the OP wishes to take the opportunity to strengthen the roof
structure, then it would also make sense to add hurricane clips to
resist uplift.

Yours, Wayne