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Thread: Buying a new house, Need the collective wisdom of members of this site

  1. #16
    Join Date
    Mar 2003
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    Quote Originally Posted by Curt Harms View Post
    I was thinking about foam too, I'd think foam would help with air infiltration from wind. One downside would be being able to modify electrical. You'd pretty much need to use surface mount devices and conduit or something like it I'd think. I've never dealt with expanding foam insulated walls so no experience.
    It's absolutely true that doing additional electrical work later is more difficult with spray foam, but that can somewhat be planned for in a shop environment by installing flexible conduit in the wall prior to having the spray foam installed. (We have closed cell spray foam in our entire 2200 sq ft home addition and I made the mistake of not putting the conduit in the wall in our media room for feeding additional future AV cables from the screen to the electronics below...and it was, um...fun...dealing with that) That said, spray foam provides about the best insulation benefit going, which mitigates it's slightly higher cost in a reasonable time period.

    OP, BTW, I agree with the comments that if you have gas available, that's what you want to use for heating. I SO wish I would have extended gas out to my shop building when I had the opportunity, but failed to realize it.
    --

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

  2. #17
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    Aug 2007
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    Meridian, ID
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    it is some what of a draw back with foam. though if you have the conduit in place before the foam there are no issues. exposed foam can be cut.

  3. #18
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    Jan 2004
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    Lewiston, Idaho
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    You should consider using natural gas for heating. Contact your local utility (gas supplier) company for assistance or an estimate what they would charge to extend the gas. I did for my shop and if I provided the dug trench, they installed a flexible gas line to my shop for a few hundred dollars which was much cheaper than paying a plumbing company to lay pipe.

    Get estimates before making any decisions on everything.
    Ken

    So much to learn, so little time.....

  4. #19
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    What exterior material does your house have?

  5. #20
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    Jan 2010
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    Bellingham, Washington
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    Quote Originally Posted by Bill Dufour View Post
    At those temps I would use better then the standard fiberglass r13. Go to Canada and get r15 for a few percent more, or use rockwool. Depending on siding spray foam might be a good idea as it will seal air leaks as well as be the most insulation per inch.
    At -40 make sure to include outlets for the car block heaters, maybe on a timer?
    Bill D
    n most northern areas code is r-19 for walls not r-13. HIgh density r-21 is also availabe in most areas.
    I
    Bracken's Pond Woodworks[SIGPIC][/SIGPIC]

  6. #21
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    Aug 2011
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    Quote Originally Posted by David Helm View Post
    n most northern areas code is r-19 for walls not r-13. HIgh density r-21 is also availabe in most areas.
    I
    That would depend a bit on how the walls are framed. R-19 wouldn't easily be possible with 3½-inch thickness interior insulation assuming 2x4 studs 16" OC & no exterior foam wrap.

    Considerably better R values could be achieved by building and insulating a second set of interior walls within the shop space. The structure would be free-standing so as to mostly eliminate thermal bridging from the outside.

  7. #22
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    Peter, R21 in 2x4 walls is possible and normal with closed cell spray foam. That's how my addition is built. We saved enough money from the lumber to more than cover the initial cost of the spray foam.
    --

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

  8. #23
    Join Date
    Sep 2013
    Location
    Wayland, MA
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    If you can swing closed cell foam than I'd pull the drywall, wire, and insulate. the air sealing is phenomenal with foam, Otherwise I'd use blown-in dense pack cellulose and run the wiring in conduit on the surface, leaving the installed walls alone. Even with the drywall off I'd probably put the wire on the surface rather than embedded-- that's what I've done in my shop. Another approach is to drop a 240 and 2-120 v outlets about every six feet around the periphery, with extras near your bench. If you get the density high enough chances are you won't have to rewire, and if you can DIY the wiring the cost of materials is nominal.

  9. #24
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    Aug 2011
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    Yes, you'd maybe get R-21 within the cavities where the 3" of closed cell foam exists but you'd still end up with losses from the 25% framing (and thermal bridging) in the rest of the wall (assuming 16" OC) eg: Douglas Fir is R1.0/inch, Hemlock is R1.2/inch, etc. When you look at whole wall thermal performance, you're only doing a bit better than maybe R-15 fiber with a full cavity fill. Building a separate interior wall structure keeps you from needing to demo any existing drywall and creates a thermal break from the building exterior minus any window locations.

  10. #25
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    If your house is sided why not remove the siding and add Tyvec or some such house wrap and then replace the siding. This would not only help stop wind but would also create a way for moisture toescape, something important if you are blowing in insulation. Without a means for moisture to escape your blown in will tend to matt and settle. Housewrap allows moisture out but not it. And it is a great 1st line of defense for windy locations.

  11. #26
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    Apr 2010
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    Houston, Texas area
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    A few thoughts: If you have fireblocks (horizontal 2* members) in your walls, then adding blown-in insulation requires twice as many holes.

    If it is windy in your area, the spray foam will be even more awesome, it will cut out the drafts.

    Garage doors are typically the weak link in any garage-shop climate control. Windows are also bad, so adding spray foam won't be very effective if your doors leak. You need to look at the entire building envelope. Don't over engineer one area and cheat in another.

    It is a common myth that gas heat is always much less expensive than electrical heat. Electricity rates range by over 200% across the USA. Check the prices in your area for both resources and do the calculations on the cost per Btu (considering the efficiency of specific gas and electrical system). Idaho, for example, is one of the cheapest states in the USA for electricity (on the average, your area may vary), so you may find that electric heat is just fine, with an efficient heater. Natural gas also seems to be pretty cheap in Idaho, so maybe that is why you live there. Or maybe it is the pure beauty .
    Mark McFarlane

  12. #27
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    Jan 2010
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    Bellingham, Washington
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    Quote Originally Posted by Peter Kelly View Post
    That would depend a bit on how the walls are framed. R-19 wouldn't easily be possible with 3½-inch thickness interior insulation assuming 2x4 studs 16" OC & no exterior foam wrap.

    Considerably better R values could be achieved by building and insulating a second set of interior walls within the shop space. The structure would be free-standing so as to mostly eliminate thermal bridging from the outside.
    The walls he was talking about are exterior which, in most northern areas, are required to be 2X6 framing.



    T
    Bracken's Pond Woodworks[SIGPIC][/SIGPIC]

  13. #28
    If you do wind up re-drywalling, throwing up soundboard for sound insulation will help keep your wife happy.

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