Door Cores

A garage door is usually selected for curb appeal and security reasons. Its structural integrity must be built to withstand constant exposure to the elements. It also receives a significant amount of wear and tear — going up and down thousands of times per year. As the largest “door” in the house, special consideration must be given to its thermal performance. Residential garages are no longer considered just for cats and bikes, but as an extension of living space. Even though building and fire codes may be significantly different for garages, they are getting increased attention because a large number are now temperature controlled. The insulation in the garage door now becomes a more obvious and important element. For commercial uses, this benefit is frequently necessary.

Expanded polystyrene (EPS) and polyurethane are the two most common types of insulation used in doors. Use of these materials provides increased energy efficiency, soundproofing and quieter operation for residential and commercial applications. EPS insulation offers several advantages over polyurethane, including stable R-value, decreased cost and ease of assembly. Insulated garage doors can be of ‘sandwich’ construction, in which the insulation is hidden between the inner and outer metal pans, or vinyl back construction, in which no metal pan is present on the inside of the door. Thickness of insulating cores for sandwich doors ranges from 1-3/8 to 3 inches thick. Vinyl back construction utilizes only EPS cores adhered to a decorative laminate which faces the inside of the garage. Such cores can also be purchased for non-insulated doors and installed by the homeowner. EPS is preferred due to its rigidity, which provides exceptional insulation and air infiltration qualities, as well as adding strength to the entire assembly. The ability to custom cut, rout or emboss the EPS to fit the exact dimensions provides a tight fit, eliminating thermal breaks.

The Door and Access Systems Manufacturers Association (DASMA) representing North American manufacturers of garage doors, rolling doors, garage door operators, vehicular gate operators and access control panels, developed ANSI/DASMA 107 “Room Fire Test Standard for Garage Doors Using Foam Plastic Insulation.” The ANSI Board of Standards Review approved the standard in

1997. Garage doors within one and two family dwellings are currently exempt from the thermal barrier requirement in the US model building codes. The National Building Code of Canada (NBCC) requires most foam insulation used in garage doors meet certain requirements. Foam plastics must be covered with a thermal barrier or meet performance based on a corner room fire test on accepted standards. The accepted standard, ULC/ORD-C263.7 “Room Fire Test Method for Garage Doors Using Foamed Plastic

Insulation,’” is expected to be incorporated into the NBCC prescriptive requirements. ULC/ORD-C263.7 recommends covering foam plastic insulation in lieu of testing. It states that two methods can be used to meet the standard: 

Foam plastic insulation must be covered with a minimum of .015” steel foil-faced foam insulation with a flame spread rating of 200 or less and the entire door assembly has a flame spread rating and no air spaces exist within the assembly.

The Canadian standard includes the following additional items not specified in the US version:

  • Use of “paper targets” as fire ignition indicators
  • Requirement of a secondary ignition burner
  • Requirement of the use of inorganic reinforced cement board 

Many DASMA members have adopted a performance-rating program to provide clear, precise and easy-to-read data about each garage door. The certified performance label was introduced in 2003 on new commercial and residential doors. Data on four key performance benefits based on standardized tests are listed: wind resistance, cycle life, thermal efficiency and fire compliance. This enables the consumer, building code inspector or contractor to easily identify if the door meets their needs and meets code requirements. With a rise in the need for insulated garage doors, thermal performance is under review. The National Fenestration Reporting Council (NFRC) has been working since 1992 via a mandate from the Department of Energy to help improve energy efficiency of all openings in buildings. In recent years, the result of their focus on windows is a universal rating system for window efficiency, with standardized performance labels. As with windows, the first step is to establish performance of current garage door products before developing rating systems.


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