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

[Brian Brown]

As mentioned, the wife and I are buying a new house. Cuss swear, cuss swear. We have finally sold ours, and found the new house. The new house is only 1.5 years old. My shop will be in the double deep third car garage portion of the house. During the process of looking at the house, I knocked on the walls of the house between garage and house, and then did the same to the garage to outer wall areas. It has nicely insulated doors, and as far as I can tell, they are quite tight in the frame. I am sure from the sound of the "knocks" that the outer walls of the garage are not insulated under the drywall, but the inner walls are. Also, the garage ceiling is not insulated. I plan to send my pipe cleaner skinny nephew up to put fiberglass batts in the attic, but I am unsure what, if anything to do about the walls. Do you think they should be insulated? Heat rises, but some will be lost through the walls also. If so, what is the best, most cost effective way to insulate previously finished walls. By finished I mean that they have been drywalled and have first tape coat. If it is necessary to insulate them, I can take down the drywall and put kraft face in, but would rather not go to that length if it is un-necessary. Blow in is also an option, and I am sure there are some others. New house, so money is definitely an issue.

Some facts that might influence your advice. I live in Idaho in the high mountain desert. The winter temps average near 0*, and -20* is not unusual. At times it can even get to -40*, but not common. The wind blows here; a lot. Often 30-40 mph in winter from the south, and the shop is on the south side of the house. Summer runs between 85*- 100*, and the wind blows some. We don't get much snow (natures insulation). I know, seriously, why would anybody live here? But I do.

I also am looking for heating ideas. The house has gas, but it will be difficult getting it to the garage. I can do electric easier. My current shop is heated by a 3 burner heater on top of a propane tank. I would really like to get away from that.

If any of you have ideas, I am all ears. Thanks in advance for your time.

[Jim Koepke]

If you have a source of firewood a wood stove might be a good choice. If one comes along at a good price it would likely get me to clear some space for it in my shop.

Another thought would be to plant a wind break on the south side of your shop/property if you can.

Blown in insulation sounds like the most practical.

jtk

[Jamie Buxton]

Sheet rock is cheap, and finishing it to garage quality is easy -- tape and one coat of mud. I'd take the rock down, install the insulation, and install new rock.

[Jim Becker]

I agree with Jamie. Remove the installed exterior wall drywall. Not only will that make insulation easier, but it will also allow you to deal with electrical modifications/additions that you'll likely want for your shop space. Then replace the wall board with new.

[Art Mann]

Good point about wiring modifications.

[Bill Dufour]

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

[Brian W Evans]

I agree that insulation is necessary, especially if you're going to heat the space. Take the drywall off so you can insulate and seal properly and do your electrical work, but don't use drywall after that. Instead, use some sort of sheathing material to seal up the walls. This is more durable and you can then screw things to the walls anywhere you want. Even with painting the sheathing white, you're not looking at more effort than replacing the drywall.

[Jim Becker]

Just don't remove the drywall on the "house" side as that's usually thicker fire-rated drywall that most codes require between a garage space and the living space. You can cover it with more sturdy material and use box extenders for any electrical if you need to do that.

[Andy Fox]

Hose-sized holes can be cut into the drywall to blow insulation into each stud cavity. If you cut the holes, you might be able to hire an insulation contractor to blow in insulation there and the ceiling for almost the same cost as doing it yourself.

[Bill Space]

Hi,

I would first cut some small holes in the drywall in question and verify that your assumption that there is no insulation in there is correct.

If no insulation is in the walls, I would as others have suggested take the wall drywall off and insulate properly. Watch some utube videos, and you will be able to do a fine job finishing the replacement drywall yourself.

For the attic area, rather than batts, consider blown in insulation. It goes fast and covers well. If necessary you can paint the ceiling with vapor barrier paint. As a reference point, I recently insulated 1200 sq ft of attic to R60 with blown in Fiberglas and it took me about three hours. It is a two man job. One to feed the machine, and one to place the material. In your climate you need about this much or more.

Bill

[Mike Heidrick]

You can blow insulation into a wall too. If it is drywall then you can hole saw a couple 2" holes or so in between stubs (typically at top and midway -save the plugs), blow in the insulation, then use the plugs from wall, tape, and mud to patch holes. Id call some insulators in your area.

[Ken Fitzgerald]

I agree with Jim about removing the drywall from the exterior walls, doing the electrical, insulating and reinstalling new drywall. It will make for a cleaner installation and suit your specific electrical needs too.

[Don Jarvie]

Since you have access to gas get a reasonable gas heater. Forget electric.

[Jim Andrew]

Agree with the others about removing drywall. Would extend the gas to the shop and heat with gas. Too many issues with insurance heating with wood, and electric is expensive to heat with.

[Curt Harms]

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

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.

[Jim Becker]

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.

[Jay Radke]

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.

[Ken Fitzgerald]

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.

[Bill Jobe]

What exterior material does your house have?

[David Helm]

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

[Peter Kelly]

n most northern areas code is r-19 for walls not r-13. HIgh density r-21 is also availabe in most areas.
IThat 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.

[Jim Becker]

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.

[roger wiegand]

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.

[Peter Kelly]

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.

[Bill Jobe]

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.

[mark mcfarlane]

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 :).

[David Helm]

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

[Eric Van Cronk]

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