What is the Best Way to Insulate a Garage?

If you want to use your garage regularly through the winter, you will often find it to be freezing cold, with portable heaters proving ineffective. In these cases, installing thorough garage insulation will allow you to retain heat, making your space usable throughout the year and saving you money on energy. 

In this guide from Building Materials Nationwide, we’ll take a look through the best garage insulation options, covering roof, wall, and floor garage insulation. We’ll look at garage insulation options in both freestanding garages and attached garages, and we’ll also show you the best way to insulate your garage door.

What are the Benefits of Insulating My Garage?

Garage insulation offers key benefits if you are looking to use your garage space, either for working on cars or as an additional living space. If you are simply looking to store your cars, then you may not need garage insulation. But if you want your garage to be a workshop, a home gym, or a play area, then garage insulation will allow it to be used throughout the winter.

If your garage is connected to your house, properly insulating it will mean that less heat will be lost when you open the connecting door. Insulation is also essential for pipes within your garage, as an uninsulated garage could lead to them freezing. If you are looking to convert your garage into a living space then you will need to insulate it, in order to comply with building regulations.

The Best Options for Garage Roof Insulation

Garage insulation is available for both flat roofs and pitched roofs. A pitched roof in a garage can be insulated much like the roof of a house, using rigid insulation boards affixed to the joists of the roof. These can be combined with multifoil sheets, offering additional insulation and ventilation, with inbuilt vapour barriers.

Rigid insulation boards can be cut to size and fitted either between joists or above them, which should be a comfortable process for those with DIY experience. A properly insulated garage roof will offer great thermal support, minimising heat loss through your roof and reducing your energy bills.

Your flat roof will be either a warm roof or a cold roof, with warm roofs being the most common. This type of flat roof has a layer of waterproofing on top, followed by a solid insulation board, a vapour barrier, timber decking, wooden joists, and a plasterboard ceiling.

Cold roofs feature solid insulation boards further down, with a pocket of cold air above them. Adding additional garage insulation to a flat roof can be done by you, but will essentially involve taking your roof apart, and as such may be better left to a professional.

View All Insulation

The Best Options for Garage Wall Insulation

If your garage has cavity walls, then opting for blown-in cavity wall insulation will offer an effective level of insulation. This process involves drilling a small hole within your wall and filling it with one of several types of insulation material. This is something that must be done by a professional, requiring experience and specialist equipment.

Before filling your cavity walls as a method of garage insulation, you should first have your walls examined by a surveyor. Houses in certain areas are unsuitable for cavity wall insulation due to high rain levels, and damaged outer walls can have serious issues with condensation when insulated. If your cavity walls are unsuitable for insulation, you can insulate them much as you would a solid wall.

If your garage has solid walls, such as breeze blocks, your options will be internal or external garage insulation. For internal installation, constructing a stud wall around your garage with metal or timber frames can allow you to use traditional thermal insulation slabs and batts within the wall, snugly fitted between the studs. You can install thermal insulation boards on top of your stud wall, or insulated plasterboards. 

This will lose you floor space but will offer a high level of garage insulation. Another option is installing a combination of insulation and dry lining board directly to the wall. These are bonded with product-specific adhesives and mechanical fixings, and offer insulation, a vapour barrier, and a surface of plasterboarding. This will use less space and allow you to easily decorate it.

External wall insulation can be a better choice for detached garage insulation. External wall insulation boards can be fitted around the walls of your garage, which is then rendered over to ensure weatherproofing. This will insulate your garage without costing any floor space.

The Best Options for Garage Floor Insulation

When looking to insulate the floor of your garage, underfloor insulation is often too costly to justify, as it would involve excavating and relaying a concrete garage floor. A more reasonable garage insulation alternative is to lay foam insulation boards across the floor, over a damp-proof membrane. The thicker the insulation board you use, the better insulated your floor will be. The cost that comes with this is lost height, but it will be worth it for the insulation benefits. If you are going to install insulation boards on the concrete, you may need to use floor levelling to achieve a flat plane.

The Best Options for Garage Door Insulation

When looking for garage insulation, insulating the garage door should be a priority, limiting a great source of heat loss. Foil insulation rolls, affixed with foil tape to the inside of the door should help prevent heat loss, without interrupting your garage doors’ opening process. There are garage door insulation kits available, offering all supplies needed.

How Much Does it Cost to Insulate a Garage?

If you are looking to insulate a garage yourself, for instance using insulation boards in a pitched roof, dry lining insulation boards on internal walls, foil insulation rolls on a door, and foam insulation boards across the floor, then you will be looking at costs in the range of several hundred pounds. If you require a professional or are using an insulation option that can only be installed by professionals, like cavity wall insulation, the costs of garage insulation could reach the thousands. Having a concrete garage foundation replaced will be a costly process.