Which heater is better for my 2 car garage?

mdntrdr said:

Sealing the door will help considerably. I would guess the blue board he refers to is 4' x 8' foam sheets. You will not get much R-value from 1". If you have access to the attic, rolling fiberglass insulation would be excellent. Radiant heat works. Anything is better then kerosene. :smile:

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Yes 4'x8' Styrofoam sheets. Some brands are pink. There is white Styrofoam bead board as well. Little cheaper but not as durable. The fiberglass in the attic is a better idea and probably less costly. R11 for 3 1/2 thickness and you can go as thick or thicker than the ceiling joists.

Any windows are most likely single pane glass. The shrink with a hair dryer plastic over the windows will help by making a sort of dead air space. The Styrofoam will burn and make toxic fumes so you would need to make sure it is away from any heat source.

You could make a false wall and hang fiberglass by stapling the craft paper backing to a 2X2 along the top of the wall and tape the bats together. A false wall need not be structural. Insulation and draft stoppage will diminish the heat BTU requirement, save you money.

My shop is a 24x24 detached garage. Insulated mostly but not completely. I use a vent less propane heater and shut it off before making any dust of fumes. It will stay 50 degrees for about an hour or two depending on the weather. 20 degree highs are common in central Iowa. I wanted to hang a gas heater but my local code says the heater must be ten feet off above the floor. My ceiling is 7' 3" and I can not put a gas line under the concrete drive. Just to costly to make it up to code so I work a lot in colder temps than I would like.

My shop area is in my basement so it has the regular house heat. I used to work in a garage, 2 stall, partly insulated, but not the important parts (the roof). In the garage I used a combination of a small wood furnace and a 35k BTU kerosene heater. It also ran on unleaded gas but smelled more than kerosene. We called them a "salamander". It heated up the garage really fast though...much faster than the wood stove. It didn't have any thermostat so it was full blast all the time. I had to be careful where I put it. The heat it produced could cause combustibles to ignite if they were anywhere near where the heat blew out.

They work well in combination with wood, gas, or electric heat if the area needs to be heated up from very cold temperatures. Wood, gas, and electric can maintain a temperature at a lower cost but can take all day to 'raise' the temp up from freezing. A salamander can get the ambient temp up fast at a higher cost (and smell).

mdntrdr said:

OK... so what's your suggestion? :huh:

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For one thing, mind the landlord. I'd probably use electric or propane heat that I take with me when I move, and learn the tricks ice fishermen use. I used two in my Michigan garage... homemade closed cell foam insoles inside oversized Sorel pack boots, and wristwarmers made from old socks with cellulose warmers stuffed in them.

If you go with electric you can air seal thoroughly (Caulk, blow foam, weatherstripping). More tedious than hanging heavy mil plastic, but water vapor will still be able to escape from that side of the wall if needed.

Do you air condition in the summer? If so, then using either heavy plastic or a single layer of rigid foam can create a hidden condensation problem on the backside of that material, because when the A/C is on, the back side - which will be exposed to outdoor air - will feel cool, condensing the humidity out of the air, and that will soak the wall covering(s) and/or structural members. Ick.

On the other hand, maybe the landlord would buy materials and let you do the labor of a proper energy-efficiency retrofit. A good source for the interlocking wheels of condensation/heating/cooling/dehumidifying is GreenBuildingAdvisor.com