Shop temperature management

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Blog entry by Ottacat posted 02-12-2014 06:10 PM 1503 reads 1 time favorited 6 comments Add to Favorites Watch

I live in Canada where it isn’t considered a cold day if the temperature is above 0° (-18° celsius for us). My shop is in an attached garage but it doesn’t have its own door to the house. I have to go outside and then in through a back door.

When I decided to convert it to a workshop it was very important to me that I be able to use all 12 months of the year. This includes our hot summers where it goes into the 90’s or the cold winters where it regularly drops below zero. The first step I did before buying anything was to insulate the three exterior walls and ceiling. I was lucky that the garage had a window so to keep it cool in the summer all it took was a window air conditioner. This was very successful all summer.

My bigger concern was winter. My house doesn’t have natural gas so I had to decide how I wanted to heat it. For this first year I decided I try out a portable 240V, 5500 watt heater I bought from Lowes. I had it wired in direclty to my panel and had a switch installed in my basement. I normally keep it turned off and keep the garage at about 40° using a small 110V heater. Because of the garage being insulated and having the one shared wall with the house I find the garage easily stays at this temperature.

When I’m ready to work I go downstairs and turn on my big electrical heater. Within an hour the shop usually goes from 40° to 60° in an hour and gets to 70° in about an hour and half. Perfect timing to have dinner and relax a bit before heading into the shop. When I’m done work and head back inside I flip back off the heat.

I find the big cement slab of the floor and all the tools act as excellent stabilizing heat sinks. I found this particularly helpful in the summer.

So far it’s worked out great. I’m always able to use my shop, even on the coldest days, the electric bills are reasonable and its not unnecessarily heated when I’m not using it. I think I’lll stick with this setup.

6 comments so far

View woodsmithshop's profile


1415 posts in 4433 days

#1 posted 02-12-2014 06:34 PM

never did like working in a cold shop. Dad’s welding shop was heated with a coal stove, it only heated the first 5 feet from it, all the tools were like ice cycles. you have to be careful, with too much temp change can cause condensation on tools then rust.

-- Smitty!!!

View dbhost's profile


5777 posts in 4120 days

#2 posted 02-12-2014 06:36 PM

I am still working on insulating my shop. 4/5 of the way done. (Front wall / overhead doors done, longest wall done, common wall with house done, ceiling / attic done. All that remains is the shorter of the side walls. I have to move stuff off the wall to be ready to come in with insulation. I do NOT want to redo my sheet rock on that wall, so blown in insulation it shall be!

So far I have found the following challenges.

#1. Air Conditioning. Since my garage is attached, and my budget isn’t huge, I opted for a 110V portable unit. Specifically a 13.5K BTU dual ducted unit. I have not yet had a hot day with the insulation and drywall in place. With insulationa as it is but no drywall last summer, it easily brought my shop temp down to the mid / lower 70s within an hour from 95 deg 90% RH. Comfortable to work in… I do want to do the following to the “System” though… I do have to put a box fan in the shop to keep the air moving around though, the fan in the AC is not strong enough to keep the air circulating which is causing some problems with hot / cold spots… #1A. Replace the 5” corrugated plastic duct from the AC with 5” insulated flex duct. I have some spare in the attic. Just need to do it. Right now the hot / output side duct is insulated with an old blanket, the intake side is uninsulated. #1B. Insulate the exposed 5” hard line coming from inside to outside the house. There is about 6” of exposed duct inside the drywall… This needs to get fixed..

Heating is less of a concern, but with this nasty cold winter, is NOT something to forget about. The effectiveness of the insulation has been VERY apparent this year. Without any sort of heat going, the shop has not gotten under 60 degrees F even with the outside temps in the 20s in an ice storm. With heat provided by a 1500 watt 110V oil filled radiator, again stirring things up with the same box fan (on low) warms the shop up to the mid 70s within an hour, on low…

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View MrFid's profile


906 posts in 2792 days

#3 posted 02-12-2014 06:52 PM

Sounds like you’ve got a good plan. Question for you: what did you use to insulate the garage walls, and what did you finish them with? I am buying a house this spring (in not-as-cold Massachusetts), and am looking forward to moving out of the basement and into the garage (unattached). I am hoping to insulate using either spray foam or fiberglass insulation, but then I am up in the air about what to put over the insulation to protect it. Did you use drywall? If so, is my best plan to leave the drywall fairly raw (i.e. no mud or joint tape or anything) so that I can see where the joists are for attaching cabinetry and shelves? Thanks for all the info you provided on temp, that answered some of my questions for sure.

-- Bailey F - Eastern Mass.

View Ottacat's profile


524 posts in 2739 days

#4 posted 02-12-2014 07:57 PM


For the insulation I used Roxul ComfortBatts. It had a slightly better R value for the same thickness and was much easier to work with than traditional pink fibreglass. After the insuluation I installed vapour barrier and sealed it. Then on top of that I put drywall sheets but no mud or paint.

View Ottacat's profile


524 posts in 2739 days

#5 posted 02-12-2014 08:02 PM


I’ve been keeping an eye on my tools for signs of rust but so far no issue. The temperature range from 40 degrees to 70 degrees doesn’t seem to cause any moisture condensation. I have been on the lookout for this as I did get some light rust on my jointer beds during temperature swings as we went from summer to fall.

View MrFid's profile


906 posts in 2792 days

#6 posted 02-13-2014 06:26 PM

Good to hear. I plan on going a similar route as you I think. Thanks for the tip on the Roxul stuff, and thanks for posting.

-- Bailey F - Eastern Mass.

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