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Re: Glulam Beams

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1. Most lumber yards have both 24F-V4 and 24F-V8 in inventory. This may vary
in some locations, but for the most part they should be available.
2. I usually specify camber for longer spans (30 ft and longer) for
residential or light commercial unless there are large point loads or other
special considerations, such as a garage header or roof slope to prevent
ponding. If calculated camber  (1.5 times dead load deflection) is less than
1/4 inch, I usually do not specify. The ANSI/AITC A190.1-1992 allows a
tolerance of 1/8 inch per 20 ft. So if you specify 1/8 inch camber for a 20
ft long beam, they could supply you a straight beam and be in conformance.
3. I believe most stock 24F-V8 beams are not cambered since they are used
for continuous and cantilevered beams that usually have small deflections. I
would go with the straight beam if the calculated deflection is small (less
than 1/4 inch).
4. Who said that camber is never used? Lumber yard? I generally do not
specify or require cambered glulams for this application. Of course, there
may be special situations where you have a heavy point load near mid span
that could create large deflections. In that situation, I would consider
specifying camber.

Bruce Pooley
Timber Design
3448 South Newland Court
Lakewood, CO 80227
phone 303-989-8701


----- Original Message -----
From: James Allen <allen(--nospam--at)xyz.net>
To: 'Sturctural Eng List Server' <seaint(--nospam--at)seaint.org>
Sent: Wednesday, December 15, 1999 2:39 PM
Subject: Glulam Beams


I have a few questions:

1. Has anyone found 24F-V8 DF/DF glulam beams 5.125 wide by 12 and 15 inches
deep to be special order items, i.e. long lead items?
2. What is your experience with camber? Do you typically specify camber?
3. I have a project with simple span window headers and one case with the
glulam header extending beyond the exterior building line as a cantilever to
support a roofed entry. I spec'd a 24F-V8 cambered to be installed upside
down so deflections would be minimized and be apparent under deadloads. What
is your opinions about this installation.
4. I used the same spec. 24F-V8 and cambered for the simple span headers, 5
feet maximum span, and was informed that camber is never used for this type
of installation. Opinions, please.

Thank you.

James Allen, P.E.