How to Insulate a Garage

If your garage feels freezing in winter or uncomfortably warm in summer, you’re definitely not alone. Garages are often one of the least insulated areas of a home, which means they can lose or gain heat very quickly. Whether you use your garage for storage, as a workshop or you’re planning to turn it into a more usable space, adding insulation is one of the simplest ways to improve comfort and efficiency.

Insulating a garage does more than just keep the space warm. It helps protect stored items from damp and temperature changes, reduces noise and improves your home’s overall energy efficiency. With the right materials and a bit of preparation, it’s a project that’s well within reach. Here’s a simple guide on how to insulate your garage properly.

Why Insulating a Garage Matters

Garages are usually built very differently from the rest of the home. Walls are often single skin brick, roofs may have little or no insulation and floors commonly sit directly on a cold concrete slab. Because of this, heat can move in and out of the space very quickly, making garages uncomfortable to use and difficult to keep at a steady temperature.

Adding insulation creates a thermal barrier that helps slow heat loss in winter and reduce heat build-up in summer. This makes the garage more comfortable to work or spend time in and can also help stabilise temperatures in nearby rooms. Insulation also plays an important role in moisture control by reducing condensation on cold surfaces, which is especially useful if you store tools, equipment or other items that could be affected by damp.

How to Insulate a Garage Floor

Garage floors are usually solid concrete, which means they absorb and transfer cold very easily. Insulating the floor can make a noticeable difference to comfort, especially if you plan to use the space regularly.

1. Using Insulation Boards on Concrete Floors

Rigid insulation boards are one of the simplest ways to insulate a garage floor, particularly when working over an existing concrete slab. XPS boards are commonly used because they are strong, moisture-resistant and cope well with load, and they can be laid over the concrete before adding a chipboard or plywood floor finish.

For projects where higher thermal performance is needed, PIR insulation boards can also be used, offering strong insulation values with less thickness.

2. Dealing with Height and Clearance

Floor insulation will raise the finished floor level slightly, so it’s important to check door clearances and thresholds before you start. Where space is limited, thinner PIR insulation boards can help improve performance without causing access issues.

3. Preventing Heat Loss Into the Ground

A surprisingly large amount of heat can escape into an uninsulated slab. By adding insulation beneath a new floor covering, you create a barrier that helps keep warmth inside the garage rather than letting it dissipate into the ground.

Insulating the Garage Roof or Ceiling

Insulating the garage roof or ceiling is one of the most effective ways to improve comfort, as a significant amount of heat is lost through this area. The right approach depends on how the roof is built, as some garages have exposed rafters while others feature flat or pitched roof structures that need different insulation methods.

Where rafters are exposed, insulation can usually be fitted directly between them, helping to retain heat without taking up too much headroom. Flat garage roofs are typically insulated either above or below the roof deck, depending on the construction, while pitched roofs often involve installing insulation between or beneath the rafters. Whichever setup you have, insulating the roof helps maintain more stable temperatures and makes the garage more comfortable to use all year round.

Insulating Garage Walls for Energy Efficiency

Garage walls are a common source of heat loss, especially in older properties or spaces that were never designed to be insulated. Adding insulation to the walls helps maintain more stable temperatures, making the garage far more comfortable to use throughout the year. The best method will depend on how the garage is constructed and the type of wall you’re working with.

Some garages have timber-framed walls, which allow insulation to be fitted neatly between the studs. Others are built with solid brick or blockwork, where insulation is usually added to the internal face before being lined. In either case, insulating the walls can make a noticeable difference to comfort and energy efficiency, particularly if the garage is attached to the house or sits below a living area.

Choosing the Right Insulation for Your Garage

The best insulation for your garage depends on a few key factors, including how the space is built, how you plan to use it and whether moisture could be an issue. Available depth in the walls, floor or roof will also influence your choice, along with the level of comfort you’re aiming for.

As a general guide:

• Stud walls: Loft rolls or mineral wool slabs

• Brick or block walls: PIR insulation or internal wall insulation

• Floor insulation: XPS boards or PIR boards

• Roof insulation: Between-rafter insulation, flat roof insulation or pitched roof insulation, depending on roof type

• Damp-prone areas: XPS insulation

Our range includes options suited to both DIY projects and professional installations, making it easier to find a solution that fits your garage and how you want to use it.

In summary, insulating a garage is one of the most effective ways to improve comfort, reduce heat loss and make the space more practical all year round. Whether you want a warmer area for regular use or better protection for stored belongings, insulation helps stabilise temperatures and supports improved energy efficiency throughout the home.

If you’re planning a garage insulation project, explore our full range of high-quality insulation products to find the best fit for your space. For tailored advice on insulating your garage, contact us and our team will be happy to help you choose the most suitable options.