A Tested Mitigation Layer Cover Board

UK commercial roofs are carrying more than they used to. As standards evolve, roof assemblies hold more equipment, and the margin for error in roof build-ups has narrowed. DensDeck^® Prime Roof Boards are manufactured specifically for roofing applications, providing a resilient roof board layer that helps strengthen and helps protect the roof assembly.

Its glass-mat-faced gypsum core is fire-resistant*, and can add compressive strength and resistance to the demanding conditions modern roof systems are exposed to. DensDeck Prime Roof Boards address fire and wind resistance, while helping to provide long-term durability as a single layer within a roof assembly.

Benefits

DensDeck Prime Roof Boards act as a durable mitigation layer within the roof assembly, adding a layer of fire resistance into the roof assembly and helping to protect insulation and membrane components beneath them. Compressive strength supports footfall and rooftop equipment loads without compromising the layers below. In assemblies comprised of a membrane, a cover board and the insulation underneath, the resistance of the assembly to puncture increases when DensDeck Prime Roof Board is an added component**. Acoustic control reduces noise transmission, and dimensional stability keeps the board performing consistently across varying temperature and moisture levels throughout its service life.

DensDeck Prime Roof Board is included in over 200,000 roof assemblies with FM Approval. Its properties support efficient installation and long-term durability on critical projects where re-access after completion is difficult or costly.

DensDeck Prime Roof Boards Application

DensDeck Prime Roof Boards are versatile additions to a variety of commercial roof systems:

1. Cover board: DensDeck Prime Roof Board provides a resilient layer

2. Substrate board: DensDeck Prime Roof Board can help provide acoustic and fire resistance

3. Recovery board: over existing roof systems, a layer of DensDeck Prime Roof Board mechanically fixed to the structure offers a flat surface for insulation layer installation

4. Parapet wall: DensDeck Prime Roof Board can be used to support Vapour Control Layer (VCL) and waterproofing layers

DensDeck Prime Roof Boards are suitable for commercial buildings and can be incorporated into a wide range of roof systems and applications, including assemblies designed to support rooftop solar (BAPV) installations. DensDeck Prime Roof Boards are non-combustible* and certified to support fire resistance over combustible and non-combustible decks.

In testing conducted by ZAG Slovenia, thermocouple readings showed significantly lower heat transfer through the roof system when DensDeck Prime Roof Board was included, indicating improved protection of the insulation layer. The gypsum core helped contribute to water evaporation within the roof board, resulting in cooling of the underlying layers within the roof assembly.

The Core Material

Gypsum is a mineral widely used in building materials because of its natural fire-resistant and stable properties. In DensDeck Prime Roof Board, the gypsum core is manufactured specifically for exterior roofing applications to perform within demanding commercial flat roof systems. A gypsum core provides dimensional stability and resilience for the life of the roof. Glass mat facers on the front and back give the board composite strength, which can help to reduce the effects of impacts and foot traffic.

With its enhanced gypsum core, coated face and back glass mats, DensDeck Prime Roof Board continues to provide broad compatibility and high performance with many roofing adhesives, and in many cases, no primer is needed when bonding directly to the coated face. Suitability for direct bonding or torching to DensDeck Prime Roof Board should be assessed by the system designer.

Installation

DensDeck Prime Roof Board is relatively lightweight compared to cementitious alternatives, and its low linear expansion means it can be installed tightly butted with staggered joints, over or under the existing insulation layer. To cut it, score with a sharp knife and snap – no heavy-duty tools required.

In modified bitumen roofs or roofs with liquid-applied waterproofing, DensDeck Prime Roof Boards may reduce the amount of adhesive needed. Consult a system designer for priming requirements and coating weights before installation.

For full technical data and guidance on specifying DensDeck Prime Roof Board for your next project, speak to our UK specification team now.

*as described and tested in accordance with ASTM E136 **modified ASTM D4833 and modified ASTM D5635

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