Learn How To Insulate A Garage Like A Pro With Simple Steps

A garage isn’t just a room to park your car. It’s usually an extra storing space to place all the non-so-used items. And it’s probably the room that you don’t pay too much attention to. This is where insulation appears. Have you ever thought about the garage’s temperature? We bet that when it’s cold outside, your garage feels like Antarctica and when it’s hot it’s like taking a trip to the sun!

Open garage door in suburban family home

There are things you can do to improve your garage, from painting the garage door (even if it’s metal) and your garage floor to insulate it. You don’t need experts to take over your garage insulation. It can be a DIY project! And we can help you with it. Here’s all the necessary information you need, including a step-by-step guide.

Why you should insulate your garage

Insulating your property means that you’ll live in a house with no heat transfer and no moisture. The basic idea of insulation is to retain a certain temperature inside a building without it being affected by the temperature outside. When it’s cold outside, the inside of an insulated house will be warm and vice versa. But how can an insulated garage benefit you?

1. It will increase energy savings on your entire house and reduce energy bills.

2. It will minimise street and generally outside noises.

3. It will reduce carbon emission entering your house.

4. It will keep your car in good condition.

5. It will make the garage ultra-usable, especially during the winter.

Types of insulation

There isn’t just an insulation type. And it depends on what you’re about to insulate. You’re going to need different insulation materials if you want to insulate the garage door, the walls or the garage floor

  • Fibreglass insulation: It’s the most common garage insulation type. You get pre-cut batts and long blankets to fit between stud walls and roof joints. If there aren’t any drywall or plywood, you can use paper-faced or encapsulated fibreglass batts wrapped in a plastic film.
  • Cellulose insulation:  It’s loose-fill insulation made from recycled newspapers and treated with a fire retardant. You are going to need a special blowing machine to blow cellulose into the walls and roof. You better use this type if you have finished walls and roof. If your garage is unfinished, you can install it by cutting holes in the wall and spraying cellulose into the cavities and then patching the holes.
  • Rigid foam panels insulation: This type is available in 1.2 x 2.4m sheets and 1.27 cm to 10.16cm thick made up of polystyrene, extruded polystyrene and polyisocyanurate. Rigid foam is probably the best option for thin walls and garage doors as it offers a high R-value per cm of thickness, plus you can cut it to fit everywhere.
  • Spray foam insulation: It’s for energy-efficient constructions as it’s great for R-value and air-sealing. This type seals leaks and gaps within the existing walls.

3 parts of an insulated garage door panels

What does R-value mean?

It is a measuring unit to calculate the thermal resistance for some insulating materials. In theory, the higher it is, the more heat resistance and better insulative qualities.

All insulation materials have a label with their R-value. When choosing one, you should know the R-value to help you find the best one for the place you live and the space you will insulate. Generally, if you live in a cold climate area, you need something with a higher R-value.

Step-by-step guide: How to insulate a garage

The first and most important step before insulating your garage is to ensure that it’s prepared. How? Clean it thoroughly and remove everything from inside to have access to the walls, floor, roof and door. You should also check for any damp issues or damages that you may need to repair. Now, let’s see how to insulate each surface in your garage.

A 2 floor beige brick house with a single garage covered with snow

How to insulate garage walls

Walls can be made of a single skin of breeze blocks or double skin breeze blocks surrounded by brick walls.

Cavity wall insulation (double skin garage)

If you have such a garage, you’ll have to address professionals as they have a boroscope and special equipment to inspect the cavity. If the cavity is empty, they will insert blown-in insulation through small holes drilled into the mortar. But, if the wall isn’t in such good condition, you’ll have to reconstruct it.

Breeze brick wall insulation

In case your garage walls are made up of a breeze block, then you’ll better construct a timber frame against the walls and install insulation slabs in between the sections of the timber frame. For extra protection, install a full multifoil insulation system over the slabs. This way, you’re going to make your living space more comfortable, improving the internal air quality.

However, fitting timber frame insulation slabs will probably minimise the floor space. Instead, you can use thinner, easily applied products with strong adhesion instead of nails and screws and apply them like wallpaper.

Just keep in mind that before applying these type of products, you might need to first apply a primer underneath and then move on to the insulation product with the foam side to the wall. Next, smooth it with a spatula and… Voila! Your garage walls are ready and insulated!

A man fitting insulation fibre in a wall

Insulate external walls

Don’t forget that you’ll have to insulate external walls, too, for better results. Fit insulation boards and render systems. You can do it using wooden shingles. You’ll create a weatherproof finish that will provide a brilliant space that can serve as a workshop, garden studio, or outdoor playroom.

Garage floor insulation

Floors are usually made from concrete slabs which tend to be very cold during the winter months. Thus, a layer of insulation is absolutely necessary! The best way to turn your garage into a comfortable living space is to use rigid foam panels insulation.

If you want to keep the existing slabs, you should lay a damp proof membrane first. Then apply the board. There are thin ones available in the market that will retain the same floor height. For floor acoustic insulation, install acoustic matting over the board. It will reduce echoes.

Garage roof insulation

The roof insulation depends on whether you have a pitched or a flat roof. In case you have a pitched roof, you’ll have to insulate it using PIR insulation boards and a multifoil system to prevent damp and mould development. These products have a great advantage because they’re quick and easy to install and don’t need special tools and skills. But, if you have a garage with a flat roof, then you have to choose whether you are going to build a warm or a cold roof.

Warm roof

To construct a warm roof, you’ll have to fit the insulation materials above it. Most homeowners prefer it as it retains the full ceiling-to-floor height and reduces the chances of condensation build-up. In case your roof isn’t fully water-resistant, you should install a vapour control layer.

A 2 floor red brick cottage house with a double car attached garage

Cold roof

Unlike a warm roof, cold roof construction needs to fit the insulator below the roof between the roof joints. It’s named like this because the outside part of it will be colder than the inside area. If you live in a cold climate with high levels of condensation, then this construction isn’t recommended. If you choose this construction, then first screw 50x50mm battens to the side of your rafters below the roof to maintain an air gap of  50mm. Leave a gap behind the fascia to ensure air will flow throughout.

Garage door insulation

 Finally, for extra insulation results, you’ll have to insulate the garage door as well. There are special garage door insulation kits available, or you can do it completely on your own by cutting a piece of foam insulation to fit within the panels.

If your garage is connected to your house, then an insulated garage door is essential to reduce heat loss. Plus, for extra insulation, you may consider replacing your existing door with a roller garage door.

How much does it cost to insulate a garage?

The cost to insulate a garage depends on the garage’s size, whether it’s finished or unfinished, labour fees, and the cost of the insulation products you’re going to use.

Lifting gates to the garage

Insulating your garage will improve the temperature and energy efficiency of both your garage and your home. It’s a bit time-consuming, but it doesn’t require any previous experience and special skills. If you have been occupied with other DIY projects, then you will manage to insulate your garage on your own! Take matters into your own hands!

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