Douglas Fir-Larch (One species or 2?) Slightly confused

[Herb C]

In my 2015 IRC code book. (Floor Joist Span R502.3.1) is has Douglas fir-larch listed as a species. Is this one species or is it saying I can use either the Douglas Fir or Larch species? Thanks in advance.

 

[mtlogcabin]

You can use either species

Douglas Fir and Western Larch

Douglas Fir is the major species for lumber produced in the West, with more volume shipped than any other species.

wwpa.org

Douglas Fir and Western Larch often grow in intermixed stands. Coastal and Inland Douglas Fir and Western Larch share similar structural performance characteristics and are often combined in dimension lumber structural products.

 

[Herb C]

You can use either species

Douglas Fir and Western Larch

Douglas Fir is the major species for lumber produced in the West, with more volume shipped than any other species.

wwpa.org

Douglas Fir and Western Larch often grow in intermixed stands. Coastal and Inland Douglas Fir and Western Larch share similar structural performance characteristics and are often combined in dimension lumber structural products.

Much appreciated mtlogcabin. Thanks for the response. I spent a few days trying to figure that out.

 

[Mark K]

Look at the grading stamp placed on the lumber.

 

[fatboy]

Similar to S-P-F, Spruce-Pine-Fir.

 

[Paul Sweet]

It is also to differentiate it from Douglas Fir-South, which isn't as strong.