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  1. #1
    Join Date
    Jun 2004
    Location
    Fruitland, Idaho
    Posts
    38

    Default 2x6 at 24"oc Exterior Walls

    Hello,

    I am currently building 2,000-3,000 sf two story homes in Idaho. I'm looking at building Energy Star homes which require a higher R value wall than I'm using now. Our exterior walls are currently 2x4 at 16"oc, and I'm thinking of going to 2x6 at 24" oc. I know that I'll need to verify siding warranties, use 5/8" drywall, but I'm wonder if there are any structural worries with going to 24" oc. I have a structural engineer working on the problem, but I'm looking for a little real work experience here.

    Thanks in advance for the help.

  2. #2
    Join Date
    Feb 2005
    Location
    Racine, WI
    Posts
    2,127

    Default Re: 2x6 at 24"oc Exterior Walls

    You can go 24" if special conditions are met. For instance, if your joists will span at 24" o.c. you can stack your joists, studs and trusses as long as they are all in line with each other. Talk with an architect about economical building practices and see what he says about reducing material requirements.
    Your guy lost. Get over it.

  3. #3
    Join Date
    Oct 2004
    Location
    maryland
    Posts
    53

    Default Re: 2x6 at 24"oc Exterior Walls

    I have done both 24" and 16" centers. I prefer the 16" center.
    The trade off in savings on studs is lost in thicker sheathing and drywall cost.
    Structurally, it is strong enough if aligned as in Bill Lacey's post, but the walls seem to have a different acoustical quality on 24" centers. I notice this when nailing off sheathing and siding. Odd!!
    You also have to pay more attention to blocking for cabinets, sinks, etc., due to increased distance.
    But hey, just my opinion.

  4. #4
    Join Date
    Jun 2004
    Location
    Branford, CT 06405
    Posts
    3,667

    Default Re: 2x6 at 24"oc Exterior Walls

    I suggest you look into keeping the 2 x 4 wall but use abetter insulation, such as sprayed Icynene. The only reason we started to build with 2 x 6s was to add insulation. When the fiberglass insulation is just thrown in the wall it's such a waste. You would be better off with insulation that actually stops air flow and fills the gaps.
    If I didn't build with ICFs, I would use the 2 x 4s and Icynene noted above.
    Take Care

    Jim

  5. #5
    Join Date
    Nov 2004
    Location
    Washington State
    Posts
    187

    Default Re: 2x6 at 24"oc Exterior Walls

    Hey Mike,
    24 inches on center has always been okay as long as trusses or rafters sit on the studs and not between otherwise it has to be 16.

    I know of no case where 24 centers were allowed in walls of a lower floor.

  6. #6
    Join Date
    Jun 2004
    Location
    SC/WA
    Posts
    224

    Default Re: 2x6 at 24"oc Exterior Walls

    Mike,
    You will find a 24" oc. spacing will give a flatter finish than 16" oc. This is especially important if you are using hardiplank siding.There is no need to use 5/8" drywall or to align the studs with the rafters if you are using a double 2x6 top plate. I should also add that 2x6 walls @ 24" oc. are OK for the first floor of a two story building.
    Ian.

  7. #7
    Join Date
    Jun 2004
    Location
    Fruitland, Idaho
    Posts
    38

    Default Re: 2x6 at 24"oc Exterior Walls

    Thanks to everybody for the quick replies.

    James -

    I can't use 2x4 walls with Icynene because Energy Star requires a minimum R19 insulation. Icynene is R3.6 per inch x 3.5" = R12.6. I realize a 2x4 wall with Icynene is probably better than a 2x6 wall with BIB, but Energy Star does not recognize this fact.

  8. #8
    Join Date
    Nov 2004
    Location
    central NH
    Posts
    67

    Default Re: 2x6 at 24"oc Exterior Walls

    Some of the foams like Corbond have higher R values per inch and will give you that R value within a 2x4 wall.

  9. #9
    Join Date
    Feb 2005
    Posts
    2,458

    Default Re: 2x6 at 24"oc Exterior Walls

    Don't worry about Energy Star, just build the best the you can afford. I think you would be better off with icyclene and either the 2x4 or 2x6.

    I built a house for my grandmother (3000 sq Cape) and was in the Energy star program. What a pain in the A**. The Energy star was going to be much more expensive to build even when you factored in the rebates they give. What they believe is not what anyone else does and the program is very rigid. Some of what they insist on is just plain stupid but you cannot talk them into anything different. We dropped out half way through because the cost vs. benefit was not worth it. I wouldn't even consider doing it again. If you do, good luck but I think you'll be surprised how much extra you will pay for design changes, HVAC, insulation, etc. Bottom line is you can build better without them.

  10. #10
    Join Date
    Jun 2004
    Location
    Houston & Washington Texas
    Posts
    12,180

    Default Re: 2x6 at 24"oc Exterior Walls

    I agree 100% with Ian.

  11. #11
    Join Date
    Nov 2004
    Location
    central NH
    Posts
    67

    Default Re: 2x6 at 24"oc Exterior Walls

    RE Energy Star
    There must be different regulations for each state - I've built two recently in NH and the "extras" over my typical building practices were 1) higher insulation values and 2) heat exchanger or continuous duty fan. I used the fan in the last one & the only "extra" was the switch which was about $90.

  12. #12
    Join Date
    Sep 2004
    Location
    CT
    Posts
    460

    Default Re: 2x6 at 24"oc Exterior Walls

    As a remodeler I find homes that have been framed 24" o.c. to be crooked, skewed and the roof always has lines showing through the shingles. Maybe it is just in my area (CT) but I feel that 24" o.c. guys are cutting corners. Go with 16" o.c. and you will get a better product. Just my opinion.

    Aaron

  13. #13
    Join Date
    Jun 2004
    Location
    SC/WA
    Posts
    224

    Default Re: 2x6 at 24"oc Exterior Walls

    Aaron,
    You're right about the lines showing through at the roof but that is mainly to do with poor installation. It can be very noticeable where OSB is used. All sheathing should be spaced 1/8" on both horizontal and butt joints. It is generally the butt joints that show through if not spaced correctly. The horizontal joints are usually (or should be) supplied with plywood clips.
    Ian

  14. #14
    Join Date
    Jun 2004
    Location
    NW CT
    Posts
    335

    Default Re: 2x6 at 24"oc Exterior Walls

    Normally I use 2x6 @16 but when I have trusses spec'd at 24"c I use 2x6 @ 24" and Engineers always spec the roof and wall sheathing at 5/8". Also better to use 5/8" rock but not critical. AR, I am in CT, you are probably seeing homes with 1/2 OSB that is causing the shadow lines.

    I would never ever again build a home with 2x4 walls, I live in one, there is no margin for error on the insulation job, I have a jillion air leaks.

  15. #15
    Join Date
    Jun 2004
    Location
    Branford, CT 06405
    Posts
    3,667

    Default Re: 2x6 at 24"oc Exterior Walls

    Mike
    I was involved at one time with the Energy Star Program, but it was discontinued here in CT a few years back. It is showing a resurgence and may be restored in CT again mid-year. However, CT Energy Star doesn't help you in Idaho.

    Now we need to build using ResCheck as a guideline to make sure we are building as a decent insulation level compared to the average. You are right that a 2 x 4 Icynene wall is better than a 2 x 6 batt insulation wall. The problem is to show the difference using infiltration comparisons and other means. This still may not comvince them, but that is a starting point. Energy Star still functions in a numbers mindset....poorly installed R19 to them is better than a solid sprayed foam which allows little if any air infiltration.

    As time allows, I'll try to create a comparison chart comparing r19 batt against Icynene and see what happens. This may take awhile but everybody knows if you stop air infiltration you're on the right track for a better insulated home. And I don't sell Icynene but I urge clients to upgrade even in an ICF structure to really get the results. As a few said above, you may want to step away from the Energy Start Program for awhile until they offer options that make sense!
    Last edited by James Eggert; 03-06-2005 at 11:42 AM. Reason: spelling
    Take Care

    Jim

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