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November 2, 2009
2x4 Framed House
We just had a contractor build us a house. I brought a structural engineer in to be sure everything was ok. The engineer pointed out that the builder framed the exterior walls with 2x4 studs, 16 inches OC. He said it was ok, but told me that a good handful of new houses are built with 2x6s on the exterior walls. I was told by the engineer that our house will be fine. Does anyone know about this? I realize that 2x6s would have allowed for more insulation, but we used the Icynene which the company said was R-19, which is good.
Comments
I was told in a construction class that I took at city tech that they started using 2x6's in the 1970's to allow for more insulation and therefore, more thermal resistance. Prior to then, most houses were made with 2x4's and many still are.
I am not an expert on insulation, but there are plenty out there that will deliver very good resistance in the smaller wall cavity made by 2x4's. Lastly, something a builder told me years ago when I was insulating a wall - don't over pack insulation as it is the air left between the fibres that provide the thermal value.
I hope this helps,
Steve
www.thetinkerswagon.com
Posted by: thetinkerswagon at November 2, 2009 5:52 PM
Using 2 x 4 ' s on exterior loadbearing walls is unheard of these days. Its not just an issue of insulation (which I dont know how you can achieve in such a narrow cavity) but one of strength. Was the builder inexperienced or just cheap?
Ed Kopel Architects, PC
Posted by: edkopel at November 2, 2009 8:12 PM
OP: Between this and your post on stucco/styrofoam, I'd think you need some serious review of the construction you're paying for. Starting to sound like your contractor might be on the verge of leaving you with multiple problems that won't unfold until after he's paid and long gone.
Posted by: vinca at November 2, 2009 8:45 PM
We had a few structural engineers at the house. We are sistering all the 2x4s on the first floor to add strength. Also, the insulation holds an r-19 value on the walls and r 30 on the roof.
For the exterior, we have a brick veneer for the 1st floor and the EIFS stucco system on the 2nd floor. As I have seen, the EIFS is the most popular way to get the stucco look for a reasonable price, plus we get the added R value of the styrofoam. Most new houses in Brooklyn are using this method, so I dont understand why vinca is so concerned about this.
I think the contractor tried to cut some corners, but we brought a few structural engineers in and the contractor is going to remedy the problem. Luckily we have not closed up the walls or anything, so this was the time to catch this. I feel confident after the engineers report that we are going to be good structurally. As for finishings and remaming work, I have seen numerous other jobs he did, so we should be all set there. We also have an interior designer who will be supervising the heck out of him once we are totally inside.
Posted by: dssguy99 at November 3, 2009 7:32 AM
vinca's concerned that you have a lack of basic knowledge about what is going on. As in, oh, they're supposed to be using 2x6's and I just realized they're using 2x4s? You should forget about the interior designer and get your architect to see what is going on before you have serious problems down the road.
BTW, I assume there were plans. Did the plans spec 2x4s or 2x6s?
Posted by: denton at November 3, 2009 8:04 AM
op...just curious, but why did you have several engineers in? Wouldn't one have done the trick?
Did your engineers look at the entire project, or only diagnose problems you knew about? I'd hate to see you posting in 6 mo's about bounding floor joists and sagging ridge beams.
Posted by: jcarch at November 3, 2009 9:50 AM
Having cut my teeth in residential architecture in the burbs, I can tell you that 2x4's at 16" o.c. is perfectly fine for two-three stories. Any structural engineer will tell you not to worry as long as the framing was done well.
In the burbs in our area, it continued to be the standard up to the mid-90's, not 70's, when it was replaced by 2x6's, not only because of the additional insulation, but also because the 2x4's were coming from such new growth trees that they were very unstable and subject to serious warpage. Contractors were throwing away huge amounts of them because they were so curved they couldn't be used for framing.
Now, in terms of your insulation, bully for you for using Icynene. It's a great product and does a great job of insulating between framing. It expands to fill all voids and hardens quickly so it doesn't get compressed and lose R value. In addition, it provides a vapor barrier which keep the moisture out of the insulation, preventing condensation within the walls. This barrier also prevents any air movement which fiberglass, or even cellulose does not. In addition to all that, it does provide a very high R-value per inch, exceeding code requirements within a 2x4 wall.
I think what you're seeing in this thread is an opinion biased by working in New York, where buildings are habitually over-structured in order to provide the required amount of fire prevention. If it weren't for fire issues, we wouldn't be building everything out of concrete block. There's no other reason why a three-story row house needs to have the same structural system as a 6-story apartment building.
Now, having said (ranted) all that, it wouldn't hurt to have the engineer look at your plans and make sure that the rest of the framing is sufficient, and to make sure that what was spec'd was actually installed. From your post, there's no reason to believe otherwise. After all, you didn't say that the plans called for 2x6's and the contractor installed 2x4's. It sounds to me like you're doing everything just fine. Just make sure the work is done well.
Jim Hill, RA, LEED AP
Urban Pioneering Architecture
Posted by: JimHill at November 3, 2009 11:46 AM
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