DIY insulate steel garage door

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Insulation is a building material used to reduce thermal transfer between exterior and interior areas of the home. By adding insulation, you can keep your home more comfortable, lower your energy bills, and reduce your impact on the environment.

While many homes already have insulation in the walls and roof, an uninsulated garage door can be the perfect opportunity to increase your insulation levels. Adding insulation to a steel garage door is a simple task for DIY homeowners, and can have a big impact on your family's comfort.

Choosing materials

Before insulating your garage door, it can help to understand how much insulation you need based on your local climate. Insulation levels are measured using R-value, which represents the thermal resistance of a product or assembly. Higher levels of thermal resistance are associated with higher R-values. A garage door should have an R-value of 5 in moderate climates, and an R-value of 10 in colder areas.

To choose the right insulating material for your garage door, compare the R-value of each to the recommended levels for your home. According to Energy Savers, fibreglass batts have an R-value between 2 and 3 per 2.5 cm (1 inch). Polystyrene foam board has an R-value between 3.8 and 5, while polyurethane foam board can range from 7 to 8 per 2.5 cm (1 inch).

If you live in a very hot region, consider using insulation faced with reflective foil to help reflect sunlight and heat energy.


Many different manufacturers sell garage door insulating kits that are sized to fit garage doors. You can find these kits at your local home improvement or hardware store, and both foam and fibreglass varieties are available. Remember that a double garage will require two kits.

Start by cutting the insulation to size using a utility knife, if necessary. Remove the paper backing from the insulation and press the foam or fibreglass to the garage door. Use a single piece of insulation for each section of the door. Add the retaining clips from the kit and use them to tuck the edges of the insulation into the frame of the door.

If you can't find a kit, consider buying your own insulation and fastening it to the door using a heavy-duty tape or adhesive. You can cover the entire width of the garage door with a single piece of material, or break the insulation into two sections to fit around locking devices or other vertical bars or chains.

Adding seals

To fully insulate your door, it's important to add appropriate weatherstripping and seals. This will minimise drafts and prevent cold air from seeping in from under the door. Use a vinyl or neoprene seal to line both sides of the door. You can choose a more economical stick-on seal or a more durable screw-on version.

For the bottom of the door, look for a large, flexible neoprene seal. Vinyl tends to be too rigid for this type of application, but neoprene is soft enough to hold up against frequent use. Stick-on versions are the easiest to install, while screw-on door bottom seals tend to last the longest.