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Re: schoo l- roof snow 125 psf - top hung joist hangers over two layers existing gypsum wall board

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Top flange hangers are designed to be nailed to and bear on an appropriate
solid wood material.  If the 2 layers of drywall extend up to the top of the
connection and compromise the bearing of the top flange hanger, then the
connection should be re-designed.

A ledger might work to support the hangers, but the ledger's connectors to
the existing structure will need to be designed to handle the offset
shear/bending situation created by the thickness of the drywall. Solid
spacers could be added (imbedded into the drywall) to prevent the ledger
connector's rotation and simplify the design (only if it is not a firewall).

The engineer needs to take another look at the connection.

Pat Clark, P.E.

-----Original Message-----
From: Haan, Scott M. <HaanSM(--nospam--at)>
To: Se-Practice List (E-mail) <se-practice(--nospam--at)>; Seaint list
(E-mail) <seaint(--nospam--at)>; IBC list (E-mail) <IBC_IRC(--nospam--at)>;
Aec-Residential List (E-mail) <aec-residential(--nospam--at)>; Jim Mattison
(E-mail) <jmattison(--nospam--at)>
Date: Friday, March 09, 2001 9:19 AM
Subject: schoo l- roof snow 125 psf - top hung joist hangers over two layers
existing gypsum wall board

>I am a plan checker looking at plans for a school alteration.  The roof
>load is 125 psf at the particular location. The plans have a detail where
>new roof wood joists are being hung off an existing wall with Simpson top
>hung joist hangers butted against 2 layers of existing gypsum wall board.
>The engineer says there is an existing similar condition at the school that
>is doing fine.  I told the architect just because it was done wrong before
>does not mean I am going to issue a permit for an incorrect new
>The reason they are getting the permit is the roof collapsed in a different
>portion of the building.
>Does Simpson have any guidelines on this type of application?   Has anyone
>had problems with this type of application?
>Scott M Haan  P.E.
>Plan Review Engineer
>Building Safety Division,
>Development Services Department,
>Municipality of Anchorage
>phone: 907-343-8183   fax: 907-249-7399