Garage insulation – different ways to insulate garage doors, walls and floors

The different benefits of insulating garage doors, walls and floors. Installing cellulose, fiberglass or foam panels can all achieve good results according to experts.

Insulating a garage with reflective foil
(Image credit: Getty Images: Boris SV Creative 1293913446)

Wondering if garage insulation for doors, walls and floors makes a difference? If yours is heated or air conditioned – either all the time or as and when needed – so it’s a comfortable and usable space, insulating a garage as well as air sealing it will help maintain the desired temperature. 

Meanwhile, if you insulate the floor of a conditioned room above an unconditioned garage, you can save both energy and money, according to the US Department of Energy. This is definitely an ideal job to target when you're dealing with the likes of attic insulation and more ways to generally improve your home's energy efficiency.

Insulating a garage door

Insulating a garage door can be a good strategy if yours tends to overheat, as well as to stop the space becoming too cold. It is possible to fit garage door insulation yourself, or call in an experienced professional to take on the job for you.

Rigid foam insulation is one option for insulating different types of garage doors. Rigid foam has a high R-value – the measure of an insulating material’s resistance to conductive heat flow. 

Want something easier to fit? ‘The best option for the garage door is a reflective foil,’ says Sean Chapman, founder of Tools‘n’Goods. ‘It’s a cost-effective and compact material that any DIYer can install using a basic garage door insulation kit.’  

Take a look at this Reach Barrier design if you like the idea of using a kit for easy installation.

‘If you do decide to insulate your garage door yourself then it is important to apply the insulation evenly across the entire garage door,’ advises Dave Krzyzak, owner of Palm Valley Garage Doors. ‘Applying unevenly can cause your garage door to go off balance and not open properly. I would recommend hiring a professional to apply your insulation unless you are really good with your hands.’

sustainable home improvements - rockwool insulation installed in home - GettyImages-1060518474

(Image credit: Getty)

Insulating garage walls

As well as insulating a garage door, consider insulating its walls especially if you're considering garage conversion or another way to turn this into liveable space. Fiberglass batts are a popular option, and can be fitted in between the wall studs. You can finish the walls with either drywall or plywood. 

Make sure you don’t compress the insulation and be aware that fiberglass can irritate skin, eyes and the respiratory tract. Always wear goggles, a mask and protective clothing when you are using this form of insulation. 

Cellulose insulation can be blown into the cavities of finished garage walls as an alternative. You will need to rent the blower as well as buy the insulation if you choose to do this yourself. 

Rigid foam panels are a further option for insulating garage walls. They need to be cut to fit inside stud walls. It’s important to avoid gaps when you’re fitting them to maximize their effectiveness.

Insulating floors over a garage

As well as knowing about garage insulation for doors and insulating a garage via its walls, a further insulating measure you might want to take is insulating floors over an unconditioned garage.

‘Installing continuous air and thermal barriers between an unconditioned garage and the conditioned spaces above can save energy and money, improve comfort, and safeguard indoor air quality,’ says the US Department of Energy.

You should air seal the gaps between the garage and the space above as well as those between the garage and the outside before you start. Pay attention to any gaps around the structure, and check weatherstripping on the garage door, any window, and door frames.

You can use blanket insulation for this project, which should be fitted between the joists. If you are using Kraft-faced insulation, which has a vapor retarder, this should face the conditioned side of the cavity you are insulating. The insulation should be in contact with the subfloor but make sure you don’t compress it.

How can I insulate my garage cheaply?

If you want to insulate your garage cheaply, consider fiberglass batts for both the walls and the ceiling. 

‘If you’re seeking a low-cost option, batt might be the ideal option,’ says David Sheppard, founder of HVAC Judge. ‘If your garage already has drywall, blown-in insulation is generally the best option, although it is more expensive. 

‘Batt insulation is inexpensive and simple to install. Depending on how handy you are and how excellent you want the finished result to seem, you may need the help of a garage contractor. It will increase your costs, but a professional will get the job done correctly.’

Considering blown-in insulation instead? ‘Blown-in insulation may be the solution if you already have drywall around your garage, but it isn’t insulated,’ he continues.

‘A contractor will come in and cut a hole in the wall, fill it with cellulose insulation, and then patch it up. Blown-in insulation is simple to install and can be completed in a matter of hours without the need for any further demolition or reinstallation. On the other hand, insulation might be more expensive because contractors typically charge a flat fee regardless of the size of the area or the amount of time it takes.’

Sarah Warwick
Sarah Warwick

Sarah is a freelance journalist and editor writing for websites, national newspapers, and magazines. She’s spent most of her journalistic career specialising in homes – long enough to see fridges become smart, decorating fashions embrace both minimalism and maximalism, and interiors that blur the indoor/outdoor link become a must-have. She loves testing the latest home appliances, revealing the trends in furnishings and fittings for every room, and investigating the benefits, costs and practicalities of home improvement. It's no big surprise that she likes to put what she writes about into practice, and is a serial house revamper. For Realhomes.com, Sarah reviews coffee machines and vacuum cleaners, taking them through their paces at home to give us an honest, real life review and comparison of every model.