To view a sample EPS Direct-to-Deck Specification, click here.

Direct Deck Illustration, click here.

Polystyrene foam roofing insulation applied directly to steel roof decks without a thermal barrier in single-ply membrane roofing systems is recognized by UL and ICC-ES. As long as it’s covered by a current ICC-ES Evaluation Report, EPS insulation can be applied directly over steel roof decks as a component of a Class A, B or C roof covering without the use of a code specified thermal barrier.

Direct-to-Deck EPS insulation is a cost-effective, durable and energy efficient solution for roof insulation. It is compatible with all major roofing materials and assemblies and available in flat, tapered and compound tapered panels in densities ranging from 1.0 to 2.0 pcf.

EPS insulation’s thermal and mechanical properties are ideal for commercial and industrial applications where R-Value and moisture resistance are important. Available in a full range of densities, in standard and custom-cut sizes, EPS insulation provides a cost effective solution for specifiers and roofing contractors without the added cost of a thermal barrier.

The benefits of EPS insulation in direct-to-deck roofing applications include:

• Energy Efficiency
  • High R-Value
  • Stable R-Value with no lost of thermal protection over life of the roof
  • Lowest unit cost per R-Value of any rigid insulation board
  • Reduced labor and material costs since no thermal barrier necessary
  • Dimensional stability – no shrinkage, tight roof insulation
• Strength
  • Available in compressive strengths from 10 – 25 psi
  • Accommodates roof loads and traffic without damage
• Design flexibility
  • Vary density, thickness and size
• Easy installation
  • Smooth, non-abrasive surface
  • No special construction techniques or tools required
• Moisture resistant
  • No mold or mildew problems
  • Not vapor barrier so venting not necessary
• Resistance to termite damage

Members of the EPS Molders Association offer product warranties that ensure thermal performance, physical properties and termite resistance. Their products meet quality control standards and meet national building codes.

ICC-ES Code Acceptance
ICC-ES acceptance criteria, AC12, establish the requirements for foam plastic insulation for fire safety performance and code acceptance. Individual EPS insulation manufacturers and the EPS Molders Association have submitted product data for ICC testing. ICC-ES reports are available from ICC-ES, Division -07 Thermal and Moisture Protection, Roof and Deck Insulation at http://www.icc-es.org/reports/index.cfm?csi_num=07220&view_details=yes

ICC-ES Evaluation Reports for EPS insulation in direct-to-deck applications:

Approve EPS insulation applied directly over steel roof decks as a component of a Class A, B, or C roof covering.
Approve use in ballasted, mechanically attached and fully-adhered assemblies
Require the steel deck to have minimum 22 gauge and a maximum 45 mil membrane
Have maximum thicknesses of:

• 9.0 inches @ 1.00 pcf density
• 7.2 inches @ 1.25 pcf density
• 6.0 inches @ 1.50 pcf density
• 4.5 inches @ 2.00 pcf density

National Building Code of Canada

The National Building Code of Canada (NBC) requirements are somewhat different. Article 3.1.14.2.1 of the NBC addresses the use of EPS insulation in metal roof deck assemblies that form part of buildings required to be of non-combustible construction. This Article indicates that EPS manufacturers must demonstrate that the insulation component in a metal roof assembly has been tested as a component in a roof assembly complying with the conditions of acceptance in CAN/ULC-S126-M. However, the requirement to demonstrate compliance with CAN/ULCS126-M is waived if any of the following requirements included in NBC Sentence 3.1.14.2.(2) are met for the roof assembly:

(a) A 12.7-mm (1/2-in.) gypsum board or other thermal barrier meeting the requirements
of CAN/ULC-S124-M is located on the underside of the foam plastic insulation.
(b) The building is sprinklered throughout.
(c) The roof assembly has a fire-resistance rating of not less than 45 minutes.

In other words, the Canadian code allows EPS direct to deck application when a sprinkler system is installed under the metal deck. Since this is a common practice in commercial
construction, EPS insulation can be used without a thermal barrier in many projects.