Double stud wall details
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| Posted in Green Building Techniques on
We are in Minnesota (Zone 6a). 2200 sq/ft single level (9′ walls), slab on grade.
I can’t seem to find much information one way or the other about 2 particular details of a double stud wall. Thoughts?
1. What are the advantages and disadvantages to put the studs in line with each other or to stagger them?
2. What are the advantages and disadvantages to build them 24″ OC or 16″ OC?
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Replies
Scott,
Q. "What are the advantages and disadvantages to put the studs in line with each other or to stagger them?"
A. Inline advantages: You can install a plywood gusset between the inner and outer studs when necessary to limit bowing. Lining them up makes sense -- after all, the studs have to be lined up at every window opening and door opening in any case.
Staggered advantages: If your total wall thickness isn't much more than the thickness of two studs, you have room for more insulation between the studs to limit thermal bridging.
Q. "What are the advantages and disadvantages to build them 24 inches OC or 16 inches OC?"
A. Some types of siding require fastening to the studs every 16 inches, so check your siding installation instructions before deciding on this one. Check with your engineer, too; 2x4s that are only 24 inches on center probably won't work, but the engineer will tell you. Remember, both walls aren't bearing walls -- usually only one of the walls is the bearing wall. Walls can be either 2x4 walls or 2x6 walls, so there are lots of variables.
Finger jointed 2x3s for the non-structural wall (usually the interior wall) lowers the thermal bridging, and makes for a pretty flat wall- flatter than standard grades of 2x4 (and WAY flatter than milled 2x3s.)
Going 24" o.c. with 2x6s can reduce the framing fraction and improve the overall performance if some attention is paid to other aspects of advance framing (single rather than double top plates, with joists/rafters aligned directly over the studs, etc.) But 2x4 16" o.c. with 2x3s for the non-structural wall can still beat that in a not-so-deep double studwall due to the better thermal break.