"john_williams" wrote in message
news:1NAid.356977$3l3.34325@attbi_s03...
I have an attached 2 floor 2 car garage that was built about 100 years
ago,
here in New Hampshire... It's balloon framed, and the second floor joists
sit on a 1 x 4 set into the Studs, which run from the ground to the gabled
roof. (It's pretty cool.)

A 1 x 4"? Does not sound sturdy.



I need to heat the first floor. I have a full size propane grill in
there,
which I can simply turn on to supply some heat...

1) Is there any reason why I shouldn't do this? Do you think it will
heat
the space from 0 degrees F up to 40 degrees F?

First, do NOT use the grill. It is not designed to be used in a closed
space and it can give off carbon monoxide. There are unvented heaters that
can be run indoors. Reddy Heater is available from 30,000 to 80,000 Btu.

Do you want to heat the garage all the time or only when you are working in
there? The answer to that will determine how much insulation you need. I
have a detached garage and I've insulated a portion of it. The 30,000 Btu
heater will not get it to 40 degrees when it is 0 outside. I get a 25 to 30
degree temperature rise. If you insulate, vapor barrier and sheetrock the
walls, do the same on the ceiling with even more insulation, you have a
chance of getting the smaller heater to do the job.

If you are going to spend short periods of time there, an infrared heater
aimed at your work area may be best. It will keep you warm instantly.