# 1970's Panelized Roof - Question

• To: SEAOC Listservice <seaint(--nospam--at)seaint.org>
• Subject: 1970's Panelized Roof - Question
• From: Roger Turk <73527.1356(--nospam--at)compuserve.com>
• Date: Thu, 14 Feb 2002 10:56:30 -0500
```Dennis,

Based on the GLB sizes in your original post, here are the properties **per
inch of width** for GLBs composed of 1-5/8" laminations:

Depth Should be   A(in^2)  S(in^3)  I(in^4)  Vol. (ft^3)

24" -> 24-3/8"    24.38    99.02    1207     .169

26" -> 26"        26.0     112.7    1465     .181

HTH

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

Dennis Wish wrote:

. > I have client who is adding 10 A/C units to the top of an existing
. > building constructed in the 70's. The roof is a panelized roof:
. > 2x4 @ 16" o.c. DF #1 Sub-Purlins - 8'-0" maximum span
. > 4x16 @ 8' o.c. DF #1 Purlins - 18'-9" maximum span
. > 6x24" DF/DF GLB (exact size not yet verified) Beam at 18'-8" apart up to
. > 47'-6" span.
. > 7x26" DF/DF GLB (exact size not yet verified) Girders at 45' Average
. > spacing and 37'-6" maximum span

. > The problem is that I can't get the GLB's to work based on a 12-PSF dead
. > load and reducible 20-psf live load (16-psf on the Beam and 12-psf on
. > the Girder). I still have to add the A/C units to the Girders.

. > What have others done to calc out an old roof for additional mechanical
. > loads on an older Masonry bldg w/ panelized roof? The building was
. > originally a Thrifty Drug Store and is being remodeled into two stores?

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