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Re: Roof Blocking

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Try looking at using an oversize block with the top shaped at the roof
plywood - say 2x8 for 2x6 rafters.  This should give full overlap of the
upper of the double top plate.  Then call out slightly staggered, 16d face
nailing at spacing needed to transfer your roof shear.

Paul Guthrie, PE
San Luis Obispo, CA


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From: Serroels, Chris/SAC <CSerroel(--nospam--at)CH2M.com>
To: 'seaint(--nospam--at)seaint.org'
Subject: Roof Blocking
Date: Wednesday, December 16, 1998 4:30 PM

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