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RE: Need specification for exterior GLB

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24F-V8 pressure treated for above ground contact.


One alternative that I see quite often is Alaska Cedar glulam – 20F-V13 combination—only the lower bending strength and MOE but the like very nice and weather well


Timber Design

Bruce Pooley Colorado PE

3448 S Newland Ct

Lakewood, CO 80227

303-350-0985 cell


-----Original Message-----
From: Dennis Wish [mailto:dennis.wish(--nospam--at)]
Sent: Sunday, October 15, 2006 5:30 PM
To: light_framing(--nospam--at)
Cc: seaint(--nospam--at)
Subject: Need specification for exterior GLB


I need to specify an exterior GLB that will be treated after installation to resist exposure to sun and the elements in a desert climate (average to be less an 16% relative humidity and as low as 5% in summer). The GLB is to support the edge of a patio cover and has a long cantilever on one side 8-feet, 17.5-feet between supports and 2-foot cantilever at the other end.  The GLB will be supported to a 12-inch square concrete column that fills a cavity of a manufactured stone surround. I will use the columns (2 columns) to resist lateral load per the 1997 UBC using an R of 2.2 for the flagpole design of the concrete columns. The manufacter of the stone surround recommends the fill using vertical steel (calculated to be 4-#6 vertical rebar and a #3 cage with an embedded column cap at the top. The foundation turns out to be 24-inch square x 3’-9” below grade and a patio flatwork will prevent lateral movement of the top of the foundation. The roof is designed for a metal roofing, 2x8 DF#2 rafters @ 16” o.c. and the sides and bottom finished with metal lath and stucco (although the designer wanted to use an exterior GLB but I did not feel it had the life that stucco can provide in this area).


I don’t know if the GLB will be painted or simply sealed with a preservative to prevent it from getting gray due to exposure to the sun. I have the AITC documents for preservatives and the wood used most in this area is DF/DF. I need a more specific recommendation (V3, V8 etc) and seem to recall, but can not locate the specification for a Visually Graded lumber that I think is a V8 when the end condition is cantilevered.


Can anyone point me to the appropriate document or give me an idea how to specify this? Would I be better off with a Parallam and if so, the deflection calculated can be as high as close to 1-inch and I would need to add a camber. I do know that commercial grade Parallams can be ordered with a camber but the question my client will have is time and availability. Any suggestions quickly?