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Thread: Convert 2x4 walls to 2x6?

  1. #1
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    Convert 2x4 walls to 2x6?

    I have some unfinished space above my shop that I would like to use for sharpening, vacuum pressing, etc. The walls are 2x4 but I wonder if there is a way to convert them to 2x6 so I can get better insulation. I feel like I can just glue and screw some lumber on to the studs. is this possible? Has anyone done it? Any advice would be greatly appreciated.


  2. #2
    Adding 2x2s to existing stud walls is the easiest way to increase insulation space. It can also be done in ceilings. When I was building my house, the carpenters couldn't get good quality 2x10s for a vaulted ceiling. So they installed 2x8s and added 2x2s to increase the insulation space. I lived in the house for 28 years. No problems.
    “Travel is fatal to prejudice, bigotry, and narrow-mindedness..." - Mark Twain

  3. #3
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    For the best insulation put up 2" rigid foam, taped to form a vapor barrier and then sheathe over that. Sheathe with plywood or OSB if you want to be able to hang things anywhere. You can fill the bays with either fiberglass or, better, blown-in cellulose. This approach has the advantage of blocking conductive losses through the framing, which are surprisingly large. The R value of rigid foam plus blown in cellulose is as good as spray foam at a much-reduced cost.

    Yes, you can also fur out the wall to create deeper bays.

  4. #4
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    DAGS "Bon Fig Wall". Its a common way to fir out walls or roof joists using strips of rigid foam. Gives you the thermal break on the studs but cheaper than using full sheets of foam. You may or may not want a vapor barrier on the inside; it depends on climate, exterior construction, whether the space is conditioned all the time, and other factors. Often you are better off with a vapor permeable air barrier.
    --I had my patience tested. I'm negative--

  5. #5
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    Quote Originally Posted by roger wiegand View Post
    For the best insulation put up 2" rigid foam, taped to form a vapor barrier and then sheathe over that. Sheathe with plywood or OSB if you want to be able to hang things anywhere. You can fill the bays with either fiberglass or, better, blown-in cellulose. This approach has the advantage of blocking conductive losses through the framing, which are surprisingly large. The R value of rigid foam plus blown in cellulose is as good as spray foam at a much-reduced cost.

    Yes, you can also fur out the wall to create deeper bays.
    Thanks, Roger. I don't think I would have thought of this. I may very well go this route.


  6. #6
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    Quote Originally Posted by Paul F Franklin View Post
    DAGS "Bon Fig Wall". Its a common way to fir out walls or roof joists using strips of rigid foam. Gives you the thermal break on the studs but cheaper than using full sheets of foam. You may or may not want a vapor barrier on the inside; it depends on climate, exterior construction, whether the space is conditioned all the time, and other factors. Often you are better off with a vapor permeable air barrier.
    Thanks! I like this idea as well. I assume this is what you're talking about: https://www.finehomebuilding.com/project-guides/insulation/breaking-the-thermal-bridge


  7. #7
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    My garage/shop was framed in 2x4 so I screwed on 2x2s with a layer of 1/2" styrofoam between to give me the same depth a a 2x6. It was quick & easy & it the insulation provides a bit more of a thermal break than all solid wood.

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    Vapor barriers are a complicated and controversial subject, highly dependent on both your climate and use of the structure. Since we're almost neighbors in terms of climate I suggested what worked well here. If this is an outbuilding with minimal sources of interior moisture then it matters a lot less what you do, but it is generally very important not to create a condensing surface inside a wall. The concerns tend to be different in summer and winter-- in the winter you're worrying about interior moisture getting inside the wall and condensing or freezing before it gets to the outside; in summer a relatively cold interior surface from air conditioning can condense moisture from humid outside air. An interior side moisture barrier can prevent the first, high enough R-value against the interior wall can prevent the second. To be sure others will disagree!

  9. #9
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    It's perfectly acceptable to fir them out with 2x2 as has been mentioned to accomplish what you want to do.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  10. #10
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    And I will throw into the mix that the firing out can be horizontal or vertical.
    Bill D

  11. #11
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    This thread sent me down a rabbit hole, of questioning my spelling and usage and the differences between furring and firring, whether you fir or firr something out or fur or furr it. This quote from Wikipedia seems to be accurate, if anyone else out there is pedantic enough to care:

    "In construction, furring (furring strips) are thin strips of wood or other material to level or raise surfaces of another material to prevent dampness, to make space for insulation, or to level and resurface ceilings or walls.[1] Furring refers to the process of installing the strips and to the strips themselves. Firring is a U.K. term for wood strips which are usually 50 mm wide, tapered and fixed above wood roof joists to provide drainage falls below roof boarding. Furring strips themselves are typically referred to as battens in the U.K. and sometimes the material is called strapping in the U.S."

  12. #12
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    Thanks to all of you. You advice is greatly appreciated - even the terminology lesson. I hate being wrong about those things.

    On a related note, I have a 2021-style gloat: I checked the price of furring strips at HD, and they are $2.28 EACH . Last night I was cleaning out my attic and found two bundles of furring strips from an earlier project. I'm pretty sure I paid around $10 for each bundle of 10. Weird gloat, I know, but it made my night.


  13. #13
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    Just to complicate it further, 2x6 fibreglass will get you r-19, add a foam sheet and you can get up to about r-5 per inch more, BUT labor to do so goes up. Buy a Dow "Froth Pak", which is a 2 part closed cell spray foam kit and you can easily get r-7 per inch, so a 2x4 wall can become r-21 plus with a little trimming. I personally think the effective r factor of spray foam is substantially higher than that because it does a perfect job of filling the space. It's a pain to retrofit anything into, but really good in the proper circumstances.

    My prefered wall insulation system on the arctic tundra/blast furnace prairies of western NE is a couple inches of spray foam plus r-13 fibreglass. Gives a nice rigid sealed wall cavity, still has some room to add wiring or whatever later on, perfect vapor barrier. Sound passes through closed cell foam easily, so the fibreglass adds some R and also makes a quieter room. In a 2x6 wall here, this gives us something higher than R-25 generally.

  14. #14
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    Dow froth-pak is roughly $600 a kit for 650 sqft of coverage (20Lb size tanks). We use the 60 gallon tanks at work for building cryogenic freezers those babies are $6500 a set! While it's great insulation, it sure isn't cheap.

  15. #15
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    Quote Originally Posted by Ryan Yeaglin View Post
    Dow froth-pak is roughly $600 a kit for 650 sqft of coverage (20Lb size tanks). We use the 60 gallon tanks at work for building cryogenic freezers those babies are $6500 a set! While it's great insulation, it sure isn't cheap.
    Not cheap for sure. For most things we just use a sub contractor with a truck mounted machine. They use 55 gallon drums of part A and B product, machine pressurizes. Pretty cool machine, wish I owned one. For jobs less than 500sqft, those guys will price higher per sqft than a froth pak, for a whole house much cheaper. Froth Pak is expensive, but gets the job done on smaller projects.

    Are the 60 gallon tanks you use pressurized?

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