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RE: WOOD: Availability of No.1 and Select Structural Grades

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Jason:

Your method in general is a good one.

My only caution is that if you ever find yourself dealing with timber size
members (and maybe even dimensional lumber) and you "detail" out the
connections, then just specifying material properties but allowing any
species could cause you some problems.  In my "world" (now timber framing
with traditional mortise and tenon joints, etc), there can be a BIG
difference between how you would want to detail a joint with pegs/drift
pins/bolts in Oak vs. DougFir.  This is due to the differences in the wood
fiber structure.  This should not be an issue for most wood type
connections using dimensional lumber, especially since most dimensional
lumber will be softwoods that don't differ too much on the wood fiber
structure (but can on strength)...but can be a serious difference for
timber construction if you also deal with hardwoods.

FYI, when we do design documents, we will generally specify the wood
species and grade, but also call out the NDS stress values that we are
using for those species/grades.  Thus, if there is a desire to substitute,
the basic information/requirements are there.

Regards,

Scott
Adrian, MI


On Fri, 12 Nov 2004, Jason W. Kilgore wrote:

> I no longer explicitly require actual grades or species.  Instead, I design
> to specific material properties (E, Fb, Fv, Fc, etc.), list them in the
> general notes or specs, then require that the contractor meet those
> properties.  I do list example grade/species combinations that meet my
> required properties, and the contractor may use MSR lumber.  I also require
> that the contractor submit the specific grade/species combinations he
> intends to use for each location.
>
> I've started doing this because I work in the central USA, and we get lumber
> from all over.  Whatever I specified, the contractor invariably called to
> say that he could get a different grade/species combination cheaper; why
> can't he use it if it's the same strength?
>
> Example notes:
> 1. SAWN HEADERS AND JOISTS SHALL MEET OR EXCEED THE FOLLOWING MINIMUM
> REQUIREMENTS (EXAMPLE SPECIES: #2 HEM FIR OR #2 SPRUCE PINE FIR):
>    Fb =   850 psi    Fv =   70 psi
>    Fc =  1150 psi    E  = 1,200 ksi
>
> 2. BEAMS INDICATED AS LAMINATED VENEER LUMBER (LVL) SHALL MEET OR EXCEED THE
> FOLLOWING MINIMUM REQUIREMENTS (EXAMPLE PRODUCT: "MICROLAM LVL" BY
> TRUSJOIST):
>    Fb = 2,600 psi     Fv =   285 psi
>    Fc = 2,510 psi     E  = 1,900 ksi
>
> As for your main question, #1 or SS lumber IS available as others have
> stated.  It also is much more expensive, and can be a special order item
> that could delay the project if the contractor doesn't bother to read the
> plans before ordering his lumber.
>
> Whenever I get into a situation where #2 won't work I try to coordinate with
> my client.  Give them the options (TrusJoist, #1, LVL, etc.) and have them
> make the decision.
>
> ---
> Jason Kilgore
> Leigh & O'Kane, LLC
> Kansas City, Missouri
>
>
>
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