Building Insulation Products Fabricated EPS

Holey Board

Cellofoam's Holey Board is a premium expanded polystyrene (EPS) insulation installed on a roof as part of a lightweight insulating concrete roof deck system. This product is made of a rigid, closed cell, foamed EPS plastic with fire retardant that is molded and cut with specified hole patterns into finished board sizes to meet LWIC roofing system specifications and project requirements. Cellofoam Holey Board is fully encapsulated in the lightweight concrete and is often installed in stair-step manner to help create a slope to meet roof top drainage requirements. A supplier of many leading United States LWIC systems, including Elastizell, Concrecel, Siplast, and Celcore, Cellofoam Holey Board provides a long-term, stable R-value, superior compressive strength, moisture resistance, and energy and cost efficiency. Unlike the products of some of our competitors, all Cellofoam Holey Board meets or exceeds ASTM C578, Standard Specification for Rigid, Cellular Polystyrene Thermal Insulation.

Photo of holey board EPS insulation / void fill
Sketch of holey board EPS insulation / void fill in a light weight concrete deck roof
Holey board EPS insulation / void fill being installed in a light weight concrete deck roof


Cellofoam Holey Board is typically manufactured in 2 x 4 ft boards with thicknesses from 1 to 16” and nominal densities of 1.0 lb/ft3. Higher densities (1.25, 1.5, and 2.0 lb/ft3) are available per LWIC system approval. Custom sizes and configurations are available; number, diameter, and location of holes vary by LWIC system and project.

About Lightweight Insulated Concrete (LWIC)

LWIC is a material used as an insulation and substrate for support and attachment of roofing membranes, particularly on industrial and commercial buildings with low slope roofs. LWIC is composed of either aggregate or cellular concrete that is specially formulated to weigh less than standard concrete. An LWIC roof system is composed of a bottom substrate of lightweight insulating concrete, generally in a slurry coat. This slurry coat is applied to the roof deck to create a flat surface into which a layer of expanded polystyrene (EPS) foam insulation board is embedded. The EPS boards are typically 1 to 16 inches thick and are manufactured with a pattern of holes (hence the name “Holey Board”). A top layer of LWIC is poured over the EPS, filling the holes in the EPS and binding the top LWIC layer to the bottom LWIC layer as well as to the EPS. Slope is created by embedding EPS boards of varying thicknesses in a stair-stepped fashion in the concrete slurry and shaping the topcoat thickness of LWIC to the final positive slope. The roof deck may a galvanized metal deck, a structural concrete (either poured-in-place or pre-cast), or an existing built-up roof membrane.

Used for over half a century, LWIC systems are proven performers in the market. LWIC roofing systems have high compressive strength and provide a solid base for built-up, modified, and single-poly roofing membranes for both new and re-roofing applications. LWIC roofs have high fire resistance, wind uplift, seismic values, thermal insulation, and sound attenuation, and consequently these roofs are often used in coastal areas for resistance to high wind loads. LWIC roofing systems also have high dimensional stability that minimizes stresses on the roof membrane system from dimensional movement.

Not all EPS is Created Equal

Because it is embedded in concrete, some EPS manufacturers unfortunately provide very low-quality EPS to LWIC producers. This can run afoul of building codes such as Florida Building Code or Miami-Dade Building Code, as well as certifications and listings by UL, FM, and others. Cellofoam manufactures premium EPS Holey Board strictly to ASTM C578 specifications and under a rigorous quality control program independently audited and inspected in all locations by UL.


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