2x4 exterior wall framing

[Dave F]

Hello,

I'm altering a room in my existing home from an enclosed sun porch to a bathroom. 3 of the 4 walls are exterior walls, and the ceiling also goes to the exterior shingles .It was necessary to completely rebuild 2 of the walls due to the fact that they were mostly windows. The home was built in 1924, and all the exterior walls are 2x4 framing. The roof rafters are also 2x4's the max span on them is about 7'. I rebuilt the walls with 2x4 framing, is this OK? is there a requirement for 2x6 framing? I know there are new requirements for insulation. I live in Connecticut. Is this OK since the building is existing?

[Jerry Peck - Codeman]

You will likely need to use a higher R-value per inch insulation, and possibly closer spaced 2x4 studs, that if you were to go with 2x6 studs.

2x6 studs provide greater structural strength than 2x4 studs, and also provide greater depth for wall insulation.

You may be able to use a 24 inch on center spacing for 2x6 studs, but may need a 16 inch on center spacing for 2x4 studs. However, if the walls were originally framed using 2x4 studs and you are just replacing the studs, make sure to use the same species of wood (or stronger) and the same or better grade stud as was there.

I've also seen construction with 3x4 studs instead of going to 2x6 studs (and 3x6 instead of 2x8), all depends on the loads and what the engineer designs and is approved by the AHJ during plan review.

Keep in mind that plumbing vent stacks and fittings may be too large in diameter to fit within a 2x4 stud wall, you may need to bump out a section with furring strips on the 2x4 studs, or use 2x6 studs in those areas. Keeping in mind that the insulation should be on the exterior side of the vent or waste stack to keep the DWV (Drain, Waste, Vent) pipe from freezing and cause issues. Most codes require that ALL piping be protected from freezing by heat tape or enclosing within the thermal envelope (or other approved means/methods to protect from freezing) ... I suspect that the Connecticut codes also include such a requirement.