DF larch, DF larch North, DF larch South 1

[awa5114]

I work in southern California. Most timber projects here are Douglas Fir Larch wood grade. However, when looking through historical wood species and grades. I never know whether to pick DF Larch, DF Larch North or DF Larch South. Can anyone shed some light into this? Thanks.

 

[BSVBD]

Contact your regional wholesale supplier / distributor that the general contractor or wood sub-contractor might purchase from.

For example, i occasionally contact Amerhart in Green Bay, Wisconsin - Kevin Huth, 920-494-4744. They are a regional supplier to general contractors as well as DIY Retailers. They may be able to refer you to a supplier in your area.

In my area, among other species, i specify DFL #2. I use the "North" design values from NDS. I also specify the design values Fb=850psi, Fv=180psi and so on, in Header and Beam Schedules, that the contractors must comply with.

Regardless of what species, it is a practice of mine to include the design values in schedules and/or general notes.

 

[cal91]

Check with your supplier as BSVBD said,

But I'm guessing you'd use DF Larch. I'm from Sacramento, and the firm I work for always used DF Larch.

 

[msquared48]

Seattle - DFL North

Mike McCann, PE, SE (WA)

 

[Triangled]

it was my understanding that DF-S was from southern Rocky Mtn areas such as NM and AZ

 

[SlideRuleEra]

While DF products from the various parts of the vast Western Region are virtually indistinguishable in terms of appearance, the growing conditions of different parts of the region contribute to the physical working properties of the species. Consequently, Douglas Fir's growing region is identified in the grade stamp.

Douglas Fir from the US coastal and inland regions is designated as DF, or when combined with Western Larch as DF-L. (Canadian DF products are identified as DF-North and have different design values.)

Douglas Fir originating from Arizona, Colorado, Nevada, New Mexico and Utah is designated as Douglas Fir-South, or DF-S.

Coastal DF represents 73%, inland DF-L represents 26%, and DF-S represents 1% of the species' production in the Western U.S.

Here is the link for the complete write up: WWPA Technical Guide

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[awa5114]

Can anyone explain to me, then, why values for Douglas Fir-Larch (NOT south OR North, simply Douglas Fir-Larch) are not present in the UBC 1982, p231 (Table No 25-A-1 - Allowable Unit Stresses - Structural Lumber). I guess this is what I was getting at from yesterdays question.