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Re: Roof Blocking

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I have been dealing more and more with wood design and doing site inspections
for one of our national accounts.  I have also framed about 200 houses since the
mid fifties and have never installed blocking for stucco as you are referring
to.  Blocking must be installed between the joist/rafters and attached to the
top plate to transfer shear forces from the roof.  The blocking should be
attached to the top plate with an anchor such as Simpson A34's.  Unless the roof
has a very steep pitch, the blocking does not necessarily need to be beveled to
the roof.  Based on the newer codes and NDS, the old conventional framing
methods don't get the job done.  If the residential work in your area is like
most I see, it is designed by a draftsman or house designer or even the framer
and load path is the way out to the back of the property after he eats too much
from the roach coach.

Serroels, Chris/SAC wrote:

> Question regarding roof blocking to the top plate:
>
> The framing for my own home is currently underway.  This happens to be my
> first venture into the timber construction arena.  When it came time to
> block between the rafters and the top plate, the framer saw my plans and got
> a strange look on his face.  He asked how in the world I intended to attach
> the blocking to the top plate.  I got a strange look on my face and asked
> why in the world that is a problem.  He then proceeded to show me "how it is
> always done".  He said that the block is held about an inch (horizontally)
> out from the top plate then nailed to the rafter tail.  The inch clearance
> is so that the stucco installers can place the foam (one coat stucco system)
> behind the blocking.  I asked why the blocking wasn't placed on top of the
> top plate and shaped to match the sheathing.  He said that if I did this,
> then the stucco people would have to plaster between the rafter tails (added
> cost).  I believe the term used to describe this was "frieze" blocking or
> frieze board.
>
> Problem is, with the blocking held out from the top plate it doesn't provide
> shear transfer between the sheathing and plate.  What I am having them do is
> double block.  One row of blocking held out from the top plate to serve as
> the frieze blocking and one row of shaped blocking on top of the plate to
> provide the shear transfer.
>
> Question is - is this unconventional (the double blocking).  If so, how is
> it done elsewhere?
>
> Chris Serroels
> CH2M HILL/Sacramento
> cserroel(--nospam--at)ch2m.com
>