Long-term energy savings through cavity wall systems

Words: Chris TobiasMason contractors are all too familiar with the fact that not all cavity wall products are created equal. Building the exterior wall from the framing out not only requires trade expertise, but knowledge of manufacturers and project intricacies.

A masonry structure built with a cavity wall system generally includes a series of components including gypsum sheathing, air and vapor barrier, continuous insulation (CI), water-resistive barrier and flashings.

A cavity wall system has been created by Firestone Building Products. The line of Enverge Cavity Wall Products includes continuous insulation (CI) exterior wall insulation, an air and vapor barrier and thru-wall flashing. These individual products work together to improve thermal performance and prevent thermal bridging in commercial buildings.

The line was developed to meet the needs of industry professionals, including mason contractors, who are working specifically to achieve long-term energy savings. It also was developed in response to advancements in building requirements for new and existing buildings as codes are refined and made stricter.

Contractors install a Firestone Building Products Enverge Cavity Wall insulation system at the University of Colorado’s new Academic Building in Denver.
Contractors install a Firestone Building Products Enverge Cavity Wall insulation system at the University of Colorado’s new Academic Building in Denver.

Air and vapor barrier

When it comes to selecting an air and vapor barrier for a wall assembly, the key is combating uncontrolled air movement and moisture. A proactive approach will not only aid in energy conservation, but guard against mold.

The Enverge Air and Vapor Barrier is an asphalt-based, self-sealing wall barrier that provides energy savings and contributes to better air quality for building occupants. Mason contractors have found that the products provide a sustainable option for building projects, due to reduced maintenance costs attributed to moisture, mold and draft control.

Engineered and manufactured to create an impermeable barrier, Enverge Air and Vapor Barrier has a consistent membrane thickness and allows up to a 90-day construction stage exposure during installation. It is self-sealing around mechanical fasteners to minimize open gaps, though foil flashing tape also can be used to seal penetrations.

The air and vapor barrier meets or exceeds several ASTM International codes including D5602, D1876, D903, E283, E96 and E330. It can be installed in temperatures as low as 14 degrees Fahrenheit.

Some general installation considerations include:
  • Surfaces should be primed using an Enverge primer.
  • Release liners must be removed at a 45-degree angle and in three-inch increments to promote correct alignment and installation continuity.
  • The membrane should be firmly rolled from the center to the outside for maximum adhesion strength.
  • Seams should overlap a minimum of two inches to ensure the most effective coverage.

Thru-wall flashing

Enverge FlashGard Thru-Wall Flashing is a flexible membrane used to protect masonry walls from water damage. The EPDM membrane was developed to maximize thermal and dimensional stability, as well as provide superior resistance to weathering, ozone and ultraviolet (UV) radiation, even when left exposed. Its flexibility in various temperatures allows for year-round installation and adaptability to irregular shapes and contours.

FlashGard also offers puncture and tear resistance; delivers expansion and contraction characteristics; offers long-lasting durability and resistance to corrosion; and yields labor and material cost savings when compared to metal flashings without compromising longevity.

Offered in a standard membrane as well as self-adhered technology, the thru-wall flashing can be installed in the mortar bed or attached to a variety of substrates using standard construction tools.

A Firestone Building Products Enverge Cavity Wall insulation system was selected for the University of Colorado’s Academic Building in Denver because of its flexibility, ease of installation, dimensional stability and significant energy savings.
A Firestone Building Products Enverge Cavity Wall insulation system was selected for the University of Colorado’s Academic Building in Denver because of its flexibility, ease of installation, dimensional stability and significant energy savings.

Continuous insulation

According to ASHRAE, continuous insulation is required in order to stop thermal bridging and help improve thermal performance of the wall assembly.

The continuous insulation offered in the Enverge Cavity Wall System line is available in coated fiberglass mat facer or aluminum foil facer — specifically, Enverge CI Glass Exterior Wall Insulation and Enverge CI Foil Exterior Wall Insulation. Each option offers the highest R-value per inch. R-value represents the capacity of an insulating material to resist heat flow. The higher the R-value, the greater the insulating power. That power is essential when it comes to long-term energy-efficiency and savings.

The Firestone Building Products continuous insulation options are developed using inorganic facers and closed-cell technology. They are formaldehyde-free and feature HCFC-free proprietary foam technology that does not contribute to ozone depletion. The thin design allows for increased gross lease space and provides low global warming potential, due to the high-embodied energy of manufacturing, as well as the aforementioned high R-value.

Enverge CI Exterior Wall Insulations also offer a Class A, FSI ≤ 25 SDI ≤ 450, ASTM E 84 performance and meet code compliance wall assembly testing under NFPA 285. Enverge CI insulation boards can be scored to 16- and 24-inch dimensions for ease of installation working around brick ties.

All Enverge Cavity Wall Products are covered by the Enverge Building Envelope Assembly Compatibility Warranty. With proper installation detailing and project management by a mason contractor, the cavity wall system will serve as the thermal, air and water resistant barrier, as well as the vapor retarder in the exterior wall assembly while complying with energy codes in virtually every climate zone.
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