Heating Detached Garage - Primer?

[The One]

Has anyone written a guide or overview to heating a detached garage?

I have a 28x32 with 13' ceilings in Northern WI.

I have heard from some people that some concrete floors can't withstand heat in winter and fracture? How can I know if my building can be heated?

Any info to get me started would be awesome. I'm hoping this can be next summers project!

 

[Showkey]

Just go back and read past posts.......there will literally be 100's of garage heat solutions.

The floor cracking.....that's a new one. Don't think that's a big concern. The concrete slab will take a long time to warm up and a long time to cool down.

Your size building in N. WI 60k to 90k btu depending on build quality, insulation and doors and windows.
Fuel NAT gas or propane are likely the fuels of choice.
Typical Menards ceiling heater will do the trick.
Using the building/shop more or every day 90+ gas home type furnace has merit.

 

[The One]

Just go back and read past posts.......there will literally be 100's of garage heat solutions.

The floor cracking.....that's a new one. Don't think that's a big concern. The concrete slab will take a long time to warm up and a long time to cool down.

Your size building in N. WI 60k to 90k btu depending on build quality, insulation and doors and windows.
Fuel NAT gas or propane are likely the fuels of choice.
Typical Menards ceiling heater will do the trick.
Using the building/shop more or every day 90+ gas home type furnace has merit.

Thanks for the info! Without insulation, how much would you estimate I'd spend on NAT gas per month if I keep the temp above freezing and fire it up to 70F 2 nights per week for a couple hours and full days on the weekend?

 

[sands35]

I'm not sure how much it will cost to heat without insulation, but insulation will probably pay back in a year or less of operation if it's currently not insulated.

 

[toyotadriver]

Double tap

 

[toyotadriver]

No insulation and keep it above freezing all winter? In WI? That's a LOT of natural gas. You NEED insulation.

Also, in my opinion, I only heat my shop to about 60 to 64 in the winter. Any hotter and it's just too warm to work in. But, that's also a personal thing.

Since you have natural gas, if you insulate well a 45k or 50k vented hanging heater will likely do it. If you don't insulate a 75k or 80k won't be enough.

 

[The One]

Thanks toyotadriver. I'll look into the best way to insulate. I'd like to keep the rafters available if I can.

Out of curiosity, how much do you think I'll be spending on heat to keep it above freezing all winter plus heating to 64F when I'm in there? I want to make sure it's worth the expense before I get too deep into this project.

 

[Showkey]

Heating a garage with no insulation will cause all sorts of problems......like ice dams and water leaks, condensation and moisture and huge bills.

Insulate this year and heat unit next year.

 

[TractorJeff]

Bare minimum you need to insulate the ceiling!
Then West wall, then North wall, other two if you can afford it this year.
So much heat will rise that a heater/furnace will never keep up.
As far as ice dams, its a garage with no insulation, so if it ice dams, what is it going to hurt/damage?
My small shop has 3.5 inch insulation in the walls and the ceiling blown 6" back in the early 80's by previous owner. I heat that with a 45k Salamander to 55/60 when I am working in there. The big portion of the building has no insulation. I use a 100k Salamander to keep the chill off when working.

 

[toyotadriver]

Thanks toyotadriver. I'll look into the best way to insulate. I'd like to keep the rafters available if I can.

Out of curiosity, how much do you think I'll be spending on heat to keep it above freezing all winter plus heating to 64F when I'm in there? I want to make sure it's worth the expense before I get too deep into this project.

Only way to know would be to do a Manual J calculation once it's insulated and see how many btus the building will need to maintain a set temp. Then you could roughly come up with an approximate amount of gas needed times your gas rate.

If I was to make a guess (and it's ONLY a guess), I'd spitball a guess that if you kept it around 45* and turned it up occasionally, as long as it was insulated then I'd guess $30 to $50 per month. Less if you left it turned off and only heated when you are using it. Quadruple or more if you don't insulate it.

Again, totally a guess.

Remember, there is nothing better than an insulated shop with a VENTED heater. In my youth, I worked on many a vehicle outside in the winter or in a drafty tiny shop with no heat. My vented heater in an insulated shop is truly AWESOME. Hard to put a value on that.

 

[Adk Mike]

Get yourself a Modine Hotdawg HD 60 and never look back

 

[Showkey]

So much heat will rise that a heater/furnace will never keep up.
As far as ice dams, its a garage with no insulation, so if it ice dams, what is it going to hurt/damage?
.

The snow will melt high on the roof.......the water will run down.....freeze at the overhang........the water will then build up behind the freeze area (ice dam) and the water leak into the garage. If it happens often and long enough the roof deck will rot.

Ice dam 101...........No or poor insulation in northern Wi , with a heated garage will be a disaster waiting to happen !

 

[TractorJeff]

Ah! Thanks, didn't really think about the sheathing was thinking more in the line of running down inside. I have tin roofs, so everything that gets soft and melts usually slides off.

 

[The One]

Is there an effective way to still retain the rafters for storage and insulate the ceiling/roof only? I have 2x4 construction.

If I can't, what is the best way to estimate the load rating of my garage to see if I can put in a ladder and floors to make an effective storage area in the attic?

It is newer construction, maybe 2006 or so.

 

[toyotadriver]

You can but with what you have to work with and your location, it'll have to be spray foam.

 

[Baada]

You can insulate the ceiling (and drywall/osb if you want) and install a ceiling pull down ladder so you can still get up to use the rafters (above the insulation) for storage. It won't be heated up above the insulation but I don't get the impression that it matters to you.

Spend the money on a metal ladder version of the pull down ladder as the wood ones can become dangerous after some time (not even sure they still sell them). I just bought mine from Menards for $129. Also, be careful how much you load the rafters up if you don't have attic storage trusses.

 

[Baada]

You can but with what you have to work with and your location, it'll have to be spray foam.

Or you can build out a support system on the trusses for regular bat insulation that has a gap to allow airflow from the eaves in between the insulation and the roof underlayment material. That would only be necessary if you wanted the rafter storage area heated also.

 

[theoldwizard1]

I'm not sure how much it will cost to heat without insulation, but insulation will probably pay back in a year or less of operation if it's currently not insulated.

Yep ! I have an uninsulated garage. With my tank top, 2 burner heater, I can be warm if I stay less than 15 feet away.

Cheapest to most expensive cost of operation (fuel)

1. Wood stove, especially if you can supply your own wood or buy in "bulk" (40' trailer load)
2. Mini-split heat pump
3. Natural gas
4. LP
5. Oil
6. Electric resistance

A mini-split heat pump will beat all others on a YEARLY basis assuming you live in climate zone 7 or less. Not all heat pumps work below 32F, so read the specs ! A backup heat source is a good idea for zone 5 - 7, unless you don't care about things freezing solid during a power outage. Bonus is A/C !

LP versus Oil depends a lot on where you live.

Electric resistance is usually the most expensive unless you live near a cheap power source (Niagara) and/or your POCO has special rates for electric heat.

 

[Showkey]

^^^^^^^^^^^
Nat gas in Northern Wisconsin is very reasonable ( Dirt cheap) and NG heater can be purchased and installed for $800 to $2000 all in depending on DIY or full HVAC contractor install.

Mini Split for Northern Wisconsin would **** as a heater...... plus high cost of install and equipment purchase and no real need for garage AC in N. WIS? Mini split are slow to recover so if if you heat the garage to 40-45* when not in use, getting it to 65-70* might take hours. In prolonged cold periods below 32* and months below 0* with lows often -25* mini splits will **** even more. Yes Mini splits have improved but for the OP application they ****.

Electric rates in N. wis will vary with location and supplier but do not think anyone would say they are low.