A cold garage is one of those problems Chicagoland homeowners tolerate for years and then fix in a single weekend of frustration — usually the first January morning the car won’t start or the workshop is too cold to use. If you are in Evanston, Northbrook, or anywhere in the north suburbs and thinking about heating your garage, there are four realistic options and they are not equally good.
This guide covers what each option costs to install, what it costs to run through a Chicago winter, and which one fits your garage.
First: Decide What “Heated” Means to You
The right system depends entirely on your target temperature, and homeowners often skip this step.
- Freeze protection (40–45°F): Keeps pipes safe, keeps the car above freezing, keeps stored paint and batteries from ruining. Modest equipment, low operating cost.
- Working comfort on demand (60–65°F): You want to spend two hours in the garage on a Saturday. Needs fast recovery, not continuous operation.
- Full-time conditioned space (68°F+, plus cooling): A gym, workshop, studio, or hobby space used daily. This is really a room addition in HVAC terms.
A garage aiming for freeze protection and one aiming for a year-round gym need completely different equipment. Be honest about which you are.
Option 1: Gas Unit Heater (Ceiling-Mounted)
The classic garage heater — a boxy unit hung from the ceiling, vented through the wall or roof, running on natural gas.
How it works: A sealed-combustion or power-vented burner heats a heat exchanger, and a fan blows warm air across the space. Sizing is straightforward: roughly 45,000 BTU for a typical insulated two-car garage in our climate, 60,000–75,000 for a three-car or poorly insulated space.
| Factor | Gas Unit Heater |
|---|---|
| Installed cost | $2,200–$4,500 (includes gas line, venting, thermostat, electrical) |
| Heats fast? | Yes — the fastest option |
| Provides cooling? | No |
| Operating cost | Low per BTU; gas is cheap in Illinois |
| Requirements | Gas line run, exterior venting, adequate ceiling height (7 ft clearance minimum) |
Best for: Detached garages, workshops used intermittently, and anyone who wants heat fast and cheap to run. This is the workhorse answer for most Evanston and Northbrook garages.
Watch out for: Combustion air and venting requirements are not optional. A garage heater installed without proper venting is a carbon monoxide risk, full stop. It also requires a permit in nearly every north suburban municipality, and a licensed gas line installation. This is not a DIY project.
Option 2: Ductless Mini-Split Heat Pump
A wall or ceiling cassette connected to an outdoor condenser — the same technology used to condition finished attics and additions.
| Factor | Ductless Mini-Split |
|---|---|
| Installed cost | $4,500–$7,500 for a single head |
| Heats fast? | Moderate — steady rather than blast heat |
| Provides cooling? | Yes, and dehumidification |
| Operating cost | Very efficient (250–350% efficient); no gas line needed |
| Requirements | Dedicated 240V circuit, outdoor unit location, reasonably tight garage |
Best for: Attached garages you want to use year-round, home gyms, studios, and anyone who also wants summer cooling. Cold-climate models from Carrier and Midea maintain meaningful capacity below 0°F, so they work in real Chicago winters — not just on paper.
Watch out for: A mini-split in an uninsulated, drafty garage will run constantly and disappoint you. Insulation is a prerequisite, not an upgrade. Also budget for the electrical work — many garages have a single 15-amp lighting circuit and nothing else, so a dedicated circuit or sub-panel is part of the job.
Option 3: Electric Resistance Heaters
Hardwired ceiling or wall units that make heat with electric elements.
Installed cost: $600–$1,800 including a dedicated 240V circuit.
The catch: Electric resistance heat is 100% efficient at converting electricity to heat, which sounds great until you compare it to a heat pump that delivers 300%. In ComEd territory, running a 5,000-watt electric heater for a few hours a day through the winter can add $60–$120 a month. It is the cheapest to install and the most expensive to run.
Best for: Small garages, occasional use, or as spot heat at a workbench. A good budget answer if you use the space a few hours a month, a bad one if you use it daily.
Option 4: Extending Your Home’s Existing System
Homeowners ask about this constantly, and the answer is almost always no — for a reason that surprises people.
Building and mechanical codes prohibit ducting your home’s forced-air system into an attached garage. The garage contains vehicles, fuel, and stored chemicals; a duct connection can pull carbon monoxide and gasoline vapor into your living space. Even in a detached garage, extending the home system means your furnace was never sized for the added load, and your house comfort suffers.
The exception: if the garage is being fully converted into finished, permitted living space with a proper fire separation, then a dedicated zone or separate system becomes appropriate — but that is a remodel, not a heating project.
Insulation Comes First (Really)
Whatever equipment you choose, insulation determines whether it works. A typical uninsulated attached garage in Evanston loses heat so fast that a 45,000 BTU heater struggles to hold 55°F on a 10°F day. The same garage insulated and air sealed holds 65°F comfortably with the same unit.
Priority order for a garage envelope:
- Weatherstrip and seal the overhead door — the single biggest leak. A new insulated door with fresh bottom seal is often the highest-value item on the list.
- Insulate the ceiling — especially if there is living space above, where you get comfort benefits in both rooms.
- Insulate the shared wall to the house (also a fire-rated assembly in attached garages).
- Insulate exterior walls and seal the rim joist.
Typical cost to insulate and air seal a two-car garage: $2,000–$5,000. It reduces both the equipment size you need and every future utility bill.
Which One Should You Pick?
| Your Situation | Recommended |
|---|---|
| Detached garage, want warm fast, gas available | Gas unit heater |
| Attached garage, want year-round use + cooling | Ductless mini-split |
| Just freeze protection, small space | Electric heater or small unit heater |
| Home gym or studio, daily use | Mini-split + full insulation |
| No gas service to the garage | Mini-split (avoids trenching a gas line) |
| Converting to living space | Design as an addition — call us first |
Permits and Safety in the North Suburbs
Evanston, Northbrook, Glenview, and Skokie all require permits for gas-fired heating appliances and for new electrical circuits. Inspections typically cover gas line pressure testing, vent clearances, combustion air, and electrical grounding. We pull permits as part of every garage heating project — an unpermitted gas appliance is a real problem when you sell the house, and an uninspected vent is a real problem long before that.
Regardless of which system you choose, install a carbon monoxide detector in the garage and in the adjacent living space. Illinois requires CO alarms within 15 feet of every sleeping area, and a heated attached garage makes that more important, not less.
Frequently Asked Questions
Can I heat my garage with a space heater?
Portable propane and kerosene heaters produce combustion byproducts and moisture in an unvented space, which is dangerous in a closed garage. Portable electric heaters on extension cords are a fire risk. If you are heating regularly, install permanent equipment.
Will heating my garage raise my home’s heating bill?
An insulated, heated attached garage typically reduces heat loss from the house through the shared wall. The garage system’s own operating cost is the real addition — usually $25–$70 per month for a gas unit heater used intermittently.
Do mini-splits actually work in Chicago winters?
Cold-climate models do. Standard models lose significant capacity around 15–20°F; cold-climate units are rated to maintain most of their capacity down to -5°F or lower. Specifying the right model matters more than the brand.
How long does installation take?
A gas unit heater is typically one day once the gas line route is set. A ductless mini-split is generally one day, plus electrical work. Insulation runs one to two days.
Is financing available?
Yes — we offer financing through Sunbit and PowerPay so you can spread the cost over time.
Let’s Get Your Garage Usable
MMDS handles the HVAC, gas piping, and electrical work for garage heating projects in Evanston, Northbrook, and across the north suburbs — one company, one permit set, one point of accountability.
Call (847) 221-6280 or request a quote online and we will walk the space with you and price the options honestly.