I am an amateur woodworker and am having a new home built. My part-time workshop will be in the garage. Where I live (central Maryland), the winters are often cold (below freezing) and occasionally much colder (+10F/-10C and below). My current home has no insulation in the garage walls or attic, so I use an electric space heater, which is almost useless when it's really cold. I am considering having the garage in the new home insulated, since it will be much easier to do before the drywall is up.
The builder is using R-20 for the exterior walls of the living spaces, but I don't need it to be insulated enough so that I can live there, I just don't want my fingers to freeze off! I am still planning on using the space heater. The entire house will have Tyvek housewrap, including the garage (whether I choose to insulate it or not).
My question is: what level of insulation should I request? The builder wants to know what level of insulation I want before they give me a quote on the price (and I can determine if it's worth it). Do I also need to have the garage door and attic insulated to see any benefit, or can I just get by with the walls? (The walls are the critical part, since I can easily add insulation to the attic and door after the fact).
A secondary question would be: is it worth it at all? One possible answer is to do nothing and just wait for warmer weather -- it's a hobby, not a profession.
UPDATE: I've asked the builder for the pricing for R-15 in the walls (can't do R-20, since the garage is framed with 2x4s, not 2x6s) and blown insulation in the attic. Still waiting to hear back from them.
UPDATE 2: The builder has quoted me over US$1400 to insulate it. Yeah, that's only $100/year, but I think I'll just wear an extra sweater, because it's not worth that much to me.