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RE: Gaps between plywood sheathing

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I looked in a 1996 "Residential & Commercial" guide and it pretty much
indicates the gaps of varying sizes are required or recommended for all
applications. 

The original question was how to keep the required panel edge distance and
still bite the stud-joist-top chord-rafter.  The answer is to very carefully
drive the nails or staples. They could be driven at an angle if necessary.
If you want to put the nails a 1/4" from the sheathing edges please do it on
your house and not mine.

I would be most concerned about gaps where the plywood would have the
oppurtunity to get really soaked. The local climate would dictate.  A moist
location in Alaska might be sheathing under exterior coverings of walls or
roofs where an appropriate vapor retarder on the heated side of the
insulation isn't installed. 


Scott M Haan P.E.
Plan Review Engineer
Building Safety Division http://www.muni.org/building
Development Services Department
Municipality of Anchorage
phone:907-343-8183  fax:907-249-7399
mailto:haansm(--nospam--at)ci.anchorage.ak.us



-----Original Message-----
From: Neil Moore [mailto:nmoore(--nospam--at)innercite.com]
Sent: Thursday, April 19, 2001 6:20 AM
To: seaint(--nospam--at)seaint.org; seaint(--nospam--at)seaint.org
Subject: RE: Gaps between plywood sheathing


Dennis:

I just grabbed the first APA publication in my timber file drawer, which is
the APA Product Guide for Performance Rated Panels.  This publication is a
January 1986 issue:

Under Panel Size and Spacing:

"Recommended spacings between panels are 1/8 inch at end joints and 1/4
inch at edge joints for APA RATED SHEATHING and 1/8 inch at both ends and
edges for APA RATED STURD-I-FLOOR, unless otherwise recommended by the
manufacturer."  (Capitol letters are as published. )

I know that my firm went through all the causes of the buckling problems
that we encountered in installed sheathing.

Neil Moore, S.E.
neil moore and associates



At 09:40 PM 4/18/2001 -0700, Structuralist wrote:
>While others are agreeing with the 1/8" spacing for plywood, I've only read
>the standard for OSB which requires the gap. I don't recall anything in the
>APA documents either on leaving expansion joints for plywood panels.
>Dennis
>
>> -----Original Message-----
>> From: George Richards, P.E. [mailto:george(--nospam--at)BORM.com]
>> Sent: Wednesday, April 18, 2001 3:46 PM
>> To: 'seaint(--nospam--at)seaint.org'
>> Subject: RE: Gaps between plywood sheathing
>>
>>
>> The numbers do not add up and I have never seen anything in APA lit. to
>> address this issue.  Engineering Judgment.
>>
>> George Richards, P. E.
>>
>> -----Original Message-----
>> From: Michael Bryson [mailto:michael.bryson(--nospam--at)englekirk.com]
>> Sent: Wednesday, April 18, 2001 1:27 PM
>> To: seaint(--nospam--at)seaint.org
>> Subject: Gaps between plywood sheathing
>>
>>
>> Typically you install sheathing with a 1/8" gap between sheets to
>> allow for
>> some expansion, correct? If the sheets are supported by a 2x
>> framing member,
>> how do you get your edge distance for a 10d nail?
>>



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