Framing a house: 2X4 vs 2X6

[Rock knocker]

Understood, but I CAN orient my rooms so "convenience" outlets (cable TV, dual nightstands with outlets at each, etc, are on interior walls

When you start trenching out foam, you'll have so much material laying on the floor, I wouldn't even for a second let an extra data location or outlet stand in the way of a sound architectural decision

 

[tkappeler]

Have you got electrical bids on it? With a proposal of how the wires are to be ran? And who is responsible for removing, repairing and replacing the insualtion? Electricians hate SIPs, and want to do all their runs in the wall. You probably have envisioned vertical runs down to the crawl space or rim. The electrician probably did not bid it that way.

That electrician would be me. In NJ, homeowners are allowed to do their own work without licenses. I still need to submit an electrical plan, have it reviewed, meet all codes ... no slack whatsoever ... probably tougher with homeowners. It will all be inspected and approved by township.

The OP was asking about 2x4 or 2x6. For me, higher R values over a standard (approx) R19 2x6 wall and less trim work building out extension jambs, etc helped make by decision.

 

[john_bud]

Around here if the lumber doesn't have a stamp, you don't pass inspection.

 

[JeffInCO]

We built our place with 2x6 exterior walls, primarily for the additional insulating value. By the time we finished our house, I had learned a lot about insulation and concluded that my decision to go with 2x6's for insulating reasons was ill-informed.

2x6 walls are nice for a variety of other reasons, as others have said, but there are more economical & effective ways to increase wall R-value, such as exterior foam, staggered studs, etc.

If you do go with 2x6's, you may want to consider placing them on 24" centers, which is allowed for 2x6's in many jurisdictions. This reduces the percent of the wall where the r-value is that of wood, rather than your insulating material. Of course, check your local codes first.

As others have mentioned, take a look at buildingscience.com. There is a wealth of information there.

Good luck,

Jeff

 

[DonnieP]

Check out the "High R-Value Wall Assembly-02" it gets high scores:

High R-Value Wall Assemblies Building Science Information

The hi R value is from the extra stuff, not the 2 x 6 versus 2 x 4. If you look at the "High R-Value Wall Assembly-01" it tells you the difference for whole wall insulation. This explains there is very little difference when just going 2 x 6 for the extra insulation.

Quoted from page:
Whole-wall R-value: Using two dimensional heat flow analysis with thermal bridging effects and average framing factors, a 2x4 wall with R-13 studspace insulation has a whole-wall R-value of R-10. Similarly a 2x6 wall with R-19 stud space insulation has a whole wall R-value of R-13.7.1 The framing factor used for standard construction framing 16 inches on center is 25%.2 These whole wall R-values could decrease even further if there is significant air leakage or convective looping, or increased framing factor.

 

[Qapla]

It may be that the code will allow you to frame on 24" centers, I know it used to (I am also in Florida) because several builders I know made their business of building 2X6. They were very successful. However, I have been in many of those houses and even though it is /was "allowed" to build on 24" centers and reduces the number of studs needed over 16" centers, I noticed something that I would not want.

I used to hang wallpaper and as such was very aware of how "flat" walls were or were not. I found that the 2X6 walls built on 24" centers had a slight "bow" in the drywall between the studs while 16" centers did not. It was slight, but it was there. It showed more when looking down something like a hallway, but, because of my profession at the time, I noticed it on all the 24" walls.

Just my :2cents:

BTW: I live in a house with 2X6 exterior walls and would not want to go back to one with less insulation. Living in the "sunshine" stated we need the better insulation in the hot months much more then for the heat.

 

[Alan L.]

My house is 2 x 4 construction but on the outside is osb and on the outside of that is 1/2" foiled foam board insulation which adds another R4 or so, or maybe R6? AND puts insulation on the outside of the studs. Outside that is an inch or more of air, then brick veneer. In the 3.5 in wall we went with Sealection 500 foam. I am very pleased with the results in this hot weather state.

 

[Rock knocker]

I used to hang wallpaper and as such was very aware of how "flat" walls were or were not. I found that the 2X6 walls built on 24" centers had a slight "bow" in the drywall between the studs while 16" centers did not. It was slight, but it was there. It showed more when looking down something like a hallway, but, because of my profession at the time, I noticed it on all the 24" walls

Very good point. Although the American Gypsum Association allows 1/2" drywall to be used 24" OC, you are best advised to use 5/8" rock in such applications.

Some professionals may disagree, I'm not a hanger, just the stressed out dude in charge on the job site

 

[Deere Dude]

It may be that the code will allow you to frame on 24" centers, I know it used to (I am also in Florida) because several builders I know made their business of building 2X6. They were very successful. However, I have been in many of those houses and even though it is /was "allowed" to build on 24" centers and reduces the number of studs needed over 16" centers, I noticed something that I would not want.

I used to hang wallpaper and as such was very aware of how "flat" walls were or were not. I found that the 2X6 walls built on 24" centers had a slight "bow" in the drywall between the studs while 16" centers did not. It was slight, but it was there. It showed more when looking down something like a hallway, but, because of my profession at the time, I noticed it on all the 24" walls.

Just my :2cents:

BTW: I live in a house with 2X6 exterior walls and would not want to go back to one with less insulation. Living in the "sunshine" stated we need the better insulation in the hot months much more then for the heat.

The cost savings for wood up front doesn't seem to be much using 2x4s on the outside walls on a normal house. I quick calculated my house and it looks like about outside 200 studs were used at 16" on center. Then figure the top plate and bottom plate is another 400 feet of 2x6 boards. It seems the savings of a 2x4 outside wall is not all that much compared to the benefits of a stronger wall and straighter looking drywall and more insulation added even though window jams may be a little more expensive. If losing floor space is an issue, make the house and extra foot longer and wider. I built a house in 1988 using 2x6s @ 24" on center and I would not do that again. With all the windows and corners and walls butting into the outside walls, it seems like there wasn't many long stretches where 24 OC would work well. I don't think I saved over 20 boards on the whole house but was more of a pain building it. The next house was 16" Centers and all is well. Good luck on your house.

 

[sdkubota]

I had icolene (spelling?) used on my home. It is a spray foam in place in the walls. The contractor talked me into using 2 x 4 since I could easily get a high R value, zero air infiltration, and more living space. After 6 years I don't regret doing it one bit.