How to Heat a Detached Garage


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When the temperatures dip below freezing, most garages become unbearably cold and uncomfortable. Whether your garage serves as parking, storage space, or workplace, you’ll want to avoid at all costs. Besides, the bitterly cold can damage your car, equipment, and other valuable tools inside the room.

To heat a detached garage, insulate the walls, ceiling and garage door, replace all worn-out weather-stripping on windows and doors, locate and seal air leaks around and through cracks, and install a garage heater.

While detached garages offer greater security, privacy, and safety than their attached counterparts, they can be trickier than that. If you’re wondering how to heat a detached garage in an efficient manner and what detached garage options are best, keep on reading.

How to heat a detached garage

Install caulking and weather-stripping.

The first thing you want to do is to identify and seal air leaks. Doing so will reduce drafts and cold spots while saving you about 10 percent of the total energy costs. Doors, knee walls, windows, plumbing vents, foundation, and wiring holes are the common points of air leakage.

However, air leaks can come from other sources that are buried under insulation. Look for signs of air leaks such as dirty spots in the insulation, and on the ceiling. You can as well feel drafts of air with your hand.  

If you can see the light between the bottom of your garage door and floor when closed, it’s time to replace the seal.

While it’s impossible to seal every crack in the garage, you can significantly reduce the air leakage by sealing the areas where the leakage is likely to be greatest, like the ones mentioned above.

How to heat a detached garage

Caulking and weather-stripping are the most common and effective air-sealing techniques. 

For garage doors, the easiest and most durable solution is to install a metal gasket channel in the gap areas. Vinyl and rubber gaskets tend to wear down quickly.

Before purchasing the weather stripping replacement, measure the gap and the width of the garage door. This will help you determine how much weather-stripping you need. Old, worn seals on the doorstop should be replaced as well.

Use a weatherproof caulk to seal gaps around windows and other smaller openings or cracks in the garage. You can tell if your window seal needs an upgrade when it rattles after you tap it.

For larger gaps like those found in plumbing vents and electrical wires, use expanding spray foam.

Install insulation (fiberglass or cellulose).

While it depends on how you use your detached garage, insulating it is essential to increase your heating system’s efficiency. Doors, walls, floor, and ceiling are the biggest sources of heat loss in garages.

So if these areas aren’t properly insulated, your garage heater won’t do much to heat your space. It will drive up your energy bills. 

If you use the garage as your work area or living space, make it as energy-efficient as possible. This means insulating the components stated above. Insulating only one part of the garage and neglecting other areas is not practicable unless you use it as storage or for parking your vehicles.

When it comes to insulating garage doors, it only makes financial sense if it is rarely used. If the door is used more frequently than average, insulation will only go so far. Warm air will keep escaping and cold air blowing in, every time the door is open.

This will leave you feeling cold even after supplying heat to space. You can still insulate your door, but it’s probably not going to change much. A much more effective solution is to insulate the door as well as the walls, ceiling, and floor.

How to heat a detached garage

Use a garage door insulation kit to insulate the door. You can either use fiberglass batting insulation with vinyl facing or expanded polystyrene rigid foam board. 

For the walls and ceiling, use fiberglass batt insulation. If your interior is not covered with plywood or drywall, opt for kraft-faced or encapsulated fiberglass batt. This type of insulation reduces the potential for mold and mildew problems.

If you’ve already installed drywall, it’s a good idea to use blow-in cellulose insulation. Made from green materials (recycled newspaper and wood fibers), the insulation provides a superior airflow barrier.

Contrary to popular misperception, cellulose insulation is not a fire hazard. It is treated with fire retardant, which slows the spread of fire when it happens.

Install a garage heater.

While sealing air leaks and adding insulation will help keep the cold air out, they won’t make much of a difference in warming your garage. So you need to supply heat to space by installing a garage heating system.

Before investing in one, consider the size of your space and temperature you want to maintain in the garage. This is to make sure the heater you want to buy is powerful enough to heat your garage.

There are different types of garage heating models available, but the most efficient include;

How to heat a detached garage

Ductless Mini-Split System

This unit is an excellent choice for detached garages. These structures are usually not connected to the central-ducted HVAC system. So installing a ductless system makes sense from a financial and efficiency perspective.

These systems consist of two components; an outdoor compressor and an indoor handler unit. A conduit that runs through the wall via a small hole connects these two units.

Ductless mini-split systems are usually available in single and multi-zone units. For free-standing garages, single systems are the best option.

While purchasing and installing these units don’t come cheap, the operational costs are lower due to their small size. Besides energy efficiency, ductless systems filter out contaminants, thus improving air quality. Another perk is that you can operate it using a thermostat.

Natural Gas Heaters

Natural gas heaters are arguably one of the most economical methods of heating a garage. Natural gas is not only inexpensive but also environmentally friendly. The biggest advantage of these heaters is that they are hooked directly to your existing gas line.

However, since gas is involved, it’s not a good idea to install it yourself. Let the licensed technicians handle it. Also, remember you need permits and inspections before installing.

Natural gas heaters come in various types, and some are more efficient and compact than others. The units include forced air systems, conventional heaters, and radiant heating.

To find a heating unit that’s the right fit for you, consider what you need them for, the size of your space, and the temperature you want to maintain in your garage.

Like other gas-fired heaters, ventilation is crucial for safe operation; otherwise, carbon monoxide can build up inside your space. If you can get one with a separate combustion chamber, the better. These units burn outside air, thus keeping room air separate from combustion air.

Electric Ceiling Heating Panels

This heating source is another great alternative for stand-alone garages. Electric heating panels are mounted between the ceiling joists above the finished ceiling. This conceals their function without, of course, compromising heat distribution. However, for this unit to be effective, the ceiling must be well insulated.

Besides saving energy, these systems spread heat quickly and evenly throughout the space. Unlike forced air systems, radiant panels don’t distribute dust and other substances. 

Installing these panels is a DIY project if you have great electrical skills and tools.

Wrap Up

You don’t have to pause your projects or avoid your garage when winter comes calling. You can easily turn your detached garage into a warm and toasty space if you follow the steps above.

Alanna Greene

Alanna is an avid traveler who lives in Michigan. In addition to writing for Temperature Master, she also sells crafts on Etsy and takes long walks through the forests near her home.

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