How to

14 October 2016

How to Properly Insulate a Garage Door

With temperatures now dropping as we draw ever closer to winter, insulation is once again at the forefront of people’s minds. If you make regular use of your garage, keeping this particular area of the property at a consistent, comfortable temperature can be a real challenge, as the brickwork itself is typically left bare and the doors, often made of metal, do little to help conserve heat.

You could simply opt to replace your existing garage door with a pre-insulated model, but this carries a substantial financial cost, so often the better solution is to look at how you can improve the insulating properties of the door already in place. Doing so could cut down your winter heating bill by a substantial amount as well as creating a more comfortable environment; a properly insulated garage door could raise the internal temperature by as much as 10-12°F in winter and lower it by approximately 20°F during summer. It also helps in reducing noise pollution.

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So, where to begin? Many people save themselves both time and effort by purchasing an insulating kit for put together specifically for use on garage doors. These kits contain either vinyl- or foil-faced batts, or in some cases foil-faced rigid foam boards, which should fit snugly into the channels of your garage door. They start off fairly cheap, with more expensive kits available which also include many of the tools you may require during installation, such as adhesive, gloves, a utility knife and dust mask. Worthy of specific mention are the retainer pins typically included in such kits. These help to secure the insulation in place and are generally considered to be the best way of doing so.

If you would rather take the DIY approach, there are a few things you have to consider. Firstly, the type of insulation you are going to use. Most people engaging in DIY insulation will opt to use some form of foil-faced rigid foam board, which can be cut down to fit the individual channels of your garage door with minimal effort, but even within this category you have some choice.

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The most prominent types of foam board are expanded polystyrene (EPS), extruded polystyrene (XPS) and polyisocyanurate (known as ‘polyiso’, or simply ‘iso’). Any of these are perfectly applicable to this particular task, so there’s no need to worry about this one too much. What you do need to make certain of however, is that whichever type of board you choose, you make sure to purchase a variety that is both foil-faced and fire-rated. Failure to do so could lead to disaster as the highly flammable boards will produce dangerous fumes when burnt.

You should also take care to select boards which are slightly thinner than your door’s interior channels to ensure a good fit. A standard garage door is approximately 1.75 inches thick, so a board with a thickness of 1.5 inches should be ideal.

In some cases the boards won’t quite fit perfectly into the door’s channels, resulting in a certain amount of movement and headache-inducing rattling. To combat this, secure the boards to the door using a suitable adhesive and consider filling larger gaps with expanding foam filler. Be sure to check the compatibility of the products however, as some types of adhesive can actually melt foam board insulation.

Img source: CSIRO ScienceImage
I should take a moment to mention batt insulation, as it is generally the more readily available and cheaper alternative. However, it is not considered to be the best option when it comes to garage doors if you’re avoiding the use of a kit. This is largely due to the fact that the thinnest standardised batt is 3.5 inches thick, much too thick for use on garage doors, and thinner varieties can be difficult to source. Compressing the batts will greatly reduce their insulating capabilities, so don’t be tempted to force in over-thick insulation. If you insist on using batt insulation, plumbing supply stores often stock a 1.5 inch variety typically used for wrapping HVAC ducts which will be better suited to the task than standard batts. As with foam board insulation, make sure the insulation is foil-faced and properly secured.

While you’re on with upgrading the door itself, there are a few other related tasks that can help in greatly increasing the impact of your work. Look at replacing the rubber sweep located on the bottom of the door, as well as installing weather strips and draft excluders. If your garage still feels a little frosty you may have to consider upgrading the insulation of the garage itself, but that’s worthy of a follow-up article is its own right. 

Sam Bonson

Sam is an aspiring novelist with a passion for fantasy and crime thrillers. He is currently working as a content writer, journalist & editor in an attempt to expand his horizons.