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RE: handling joist deflections / alignment when in parallel with bearing wall

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I think Harold has the right solution (as he always does). Place the joist
away from the wall (I'd use a standard joist spacing, not the 2'-6"), and
attach the deck to an embed plate or angle.

It is important to keep the joist away from the wall when running parallel.
When loading is applied to the roof, the joist will deflect, but the wall is
fixed, and you put plenty of flexure into the roofing material over a very
short distance. Good place for a roof leak to develop over time,
particularly when roofing materials get brittle.

Bob Shaw
Steel Structures Tech Center
www.steelstructures.com

-----Original Message-----
From: Khosrownia, Ghassem SPK [mailto:GKhosrownia(--nospam--at)spk.usace.army.mil]
Sent: Tuesday, June 06, 2000 7:42 AM
To: 'seaint(--nospam--at)seaint.org'; Darrel E. Marchall (E-mail)
Subject: handling joist deflections / alignment when in parallel with
bearing wall


A nagging problem that needs good solid solution!

Situation:
Roof joists run in parallel with CMU bearing wall.
Roof is gabled, joists will be double gabled (no ridge beam).
CMU wall follows slope of roof.

Problem:
Camber and deflection of joists make it nearly impossible to line up with
the top of the wall?
Construction tolerances for the wall and bearing of the joist could compound
this effect.

Solution:
Specify top of the wall to be slightly lower than the bottom of the decking.
Use light enough decking so it is a bit more flexible.
For interior walls running in parallel with the joists discontinue the
decking to obtain more flexibility. Weld both ends of the decking to the
steel bearing plate on top of the wall. Use washers or small plates to
compensate for the inaccuracy.

These are not meant to be independent solutions, rather a total recipe.

What do you think. What have you done to remedy this situation?

Ghassem.