Choosing whether to decrease stud spacing or increase lumber grade for wooden stud walls
Choosing whether to decrease stud spacing or increase lumber grade for wooden stud walls
(OP)
First post 
I have recently started designing wooden stud walls using Woodworks Sizer. For a basic interior 2x4 wall, I start out with 2x4 DFL Stud Grade @ 24" on center. Oftentimes, these parameters aren't sufficient due to one criterion or another and I have to either decrease the stud spacing or increase the lumber grade. How should I make the judgment whether to decrease the stud spacing or increase the grade of lumber? Is there a reason to prefer tweaking one parameter over the other with respect to cost, constructibility, and the different design values?
(Part of the issue is that I'm a chemical engineering grad converted to a structural Engineer-In-Training so I'm still learning the theoretical side of structural design. I do want to learn though!)

I have recently started designing wooden stud walls using Woodworks Sizer. For a basic interior 2x4 wall, I start out with 2x4 DFL Stud Grade @ 24" on center. Oftentimes, these parameters aren't sufficient due to one criterion or another and I have to either decrease the stud spacing or increase the lumber grade. How should I make the judgment whether to decrease the stud spacing or increase the grade of lumber? Is there a reason to prefer tweaking one parameter over the other with respect to cost, constructibility, and the different design values?
(Part of the issue is that I'm a chemical engineering grad converted to a structural Engineer-In-Training so I'm still learning the theoretical side of structural design. I do want to learn though!)






RE: Choosing whether to decrease stud spacing or increase lumber grade for wooden stud walls
RE: Choosing whether to decrease stud spacing or increase lumber grade for wooden stud walls
RE: Choosing whether to decrease stud spacing or increase lumber grade for wooden stud walls
16" o/c is mighty common stud and framing spacing for light wood framing. Many std. details and conditions work around and because of that spacing. Going from 2x4's to 2x6's at 24" or 16" o/c allows for wall load increases and accommodates vent stacks and other mech. equip. a bit better and also allows for improved insulation thickness. 24" spacing usually means that you want to start to stack the framing in continuous vert. lines or you will have trouble with top plate loading, etc. Changing lumber grade in the same location/area or on similar conditions and details might be asking for trouble, because there is a 50-50 chance that the builder will use all the good stuff in all the wrong places, unless you provide very explicit direction, management and inspection.
RE: Choosing whether to decrease stud spacing or increase lumber grade for wooden stud walls
After concluding that it's a good idea to start with 16" on center stud spacing, I would then look at a readily available, lower grade of material for the area in which the building will be constructed. It's not a good idea to rely on the contractor to notice that a higher-than-standard grade of material was specified... again, they'll either miss it altogether or put it in the wrong place. Any "savings" in material being specified will be eaten up by mistakes/additional labor, assuming someone actually notices a mistake was made. Keep it simple.
RE: Choosing whether to decrease stud spacing or increase lumber grade for wooden stud walls
RE: Choosing whether to decrease stud spacing or increase lumber grade for wooden stud walls
RE: Choosing whether to decrease stud spacing or increase lumber grade for wooden stud walls
I pretty much call for #2 HF or DF. The low crushing strength on HF can become problematic and often drives me to DF. SP isn't used in my area.
RE: Choosing whether to decrease stud spacing or increase lumber grade for wooden stud walls
A confused student is a good student.
Nathaniel P. Wilkerson, PE
www.medeek.com
RE: Choosing whether to decrease stud spacing or increase lumber grade for wooden stud walls