Replies

1. 
   user-2310254 | Feb 26, 2017 09:17pm | #1

   Where are you located? That information is essential before anyone can offer advice.

2. 
   JATotter | Feb 26, 2017 11:55pm | #2

   I am in Rhode Island

3. GBA Editor
   Martin Holladay | Feb 27, 2017 06:01am | #3

   There are two basic approaches: (1) you can insulate the walls from the outside, or (2) you can insulate the walls from the inside.

   With a concrete block wall, outside insulation is always preferable. You can dig a trench around the perimeter of the building, about 18 or 24 inches deep, and install vertical EPS (rigid foam) insulation from the bottom of the trench to the top of the above-grade wall. Then finish with synthetic stucco. (This is the EIFS approach.)

   If you are working from the interior, you still need to install rigid foam against the concrete block wall; I recommend 2 inches of EPS or polyiso. Once this layer of rigid foam is installed, you can frame up a 2x4 wall and fill the wall with any kind of insulation you want. If you insulate the above-grade walls on the interior, you still need to dig a trench around the perimeter of the slab so that you can install vertical rigid foam to protect the perimeter of the slab. The above-grade portion of this exterior insulation needs to be protected with metal flashing.

   Needless to say, you'll need ceiling insulation, too.

   -- Martin Holladay

4. 
   user-6759891 | Mar 13, 2017 08:57pm | #4

   I live in climate zone 7a (Alberta) and planning to insulate my garage, also with the intent of using it as a woodworking shop. Apart from my own comfort, I want to provide as reasonably consistent of an environment as possible for storing lumber.

   There's no external insulation and it's constructed with 2x4 wood studs 16" oc so I'm planning to install Roxul R14. There is a reasonably-sized natural gas furnace in inside that's yet to be fired up.

   I'm debating whether to add 1" of rigid foam (foil-faced GPS @ R5) on the interior side under the drywall. This can also pass code here as a vapor barrier when sealed. I know it will give me some level of continuous thermal breaking from the studs and help better air seal. I'm just curious if I will notice or benefit from having this extra layer?

   Cheers
   Todd

5. GBA Editor
   Martin Holladay | Mar 14, 2017 05:36am | #5

   Todd,
   You probably won't notice the difference physically (because the air temperature in your garage depends on the thermostat setpoint, not the insulation level in the walls). But you will notice the difference when you pay your energy bill.

   Whether or not the upgrade is worth it depends on how many hours per month you spend in your garage, and your local fuel cost.

   -- Martin Holladay