What are the most popular flat roof build-up types for mission-critical environments?

Mission-critical low slope and flat roof systems protect some of the world’s most important buildings. These include museums and libraries that house valuable documents and irreplaceable artefacts. Data centres, biotech facilities, manufacturing centres and other crucial infrastructure buildings such as airports are also more frequently referred to as mission critical environments.

The building performance requirements for each of these buildings are different, and so the driver for specification of roof types also differs. The emphasis for data centre roofs and biotech building roofs is on functional, durable, and robust roof build-ups that minimise the risk of any operational downtime. The building envelope must offer enhanced protection for the often-expensive equipment within these buildings. Installation speed is also of the essence. The sooner the data centre is weatherproofed, the sooner it can operate and create revenue. Flat or low slope roofs with a build-up of metal decks with single-ply or reinforced bituminous membranes and metal top sheets are the most specified roof types.

Manufacturing facilities have similar drivers, but there is often the need for acoustic control, especially if the building is in close vicinity to a residential area or in a place where protection of the environment from outbound noise is critical. The roof specification is similar to that of data centres, but additional elements are required to increase the acoustic performance of the roof system.

Airports roof build-ups combine some of the requirements for robustness and longevity with pivotal drivers: aesthetic appeal and user comfort. Acoustic comfort is of specific concern in this environment. Airport roof build-ups tend to vary. Standing seam metal roofs over metal deck, especially stainless steel, and aluminium as a top covering, are perhaps the most commonly specified build-up. Standing seams roofs offer excellent scope for visually attractive designs.

What are the main hazards in mission critical environments

Anything that interrupts the operation of a mission critical facility can be qualified as a hazard. Data centres, biotech, and critical manufacturing centres operate 24-hours a day, seven days a week. Any operational downtime could mean that the mission-critical facility and all the businesses that rely on its uninterrupted service will fail to achieve their business objectives. In the case of airports, the need for continuous service is accompanied by the requirement to create a healthy and comfortable space and protect both public and employees. We will consider some of the main areas where roof build-up performance can help with risk management and potentially prevent downtime:

• Fire performance
• Robustness
• Weather protection
• Roof access
• Acoustic Performance

Specifications for roof build-ups in relation to fire performance, have seen a considerable shift in recent years. This is likely caused by the unfortunate events of recent high-profile fires in buildings across the world. Whilst these mainly were related to cladding, roof specification has seen a shift to ensure the best possible fire rating. Mineral wool is preferred in roof assemblies for thermal insulation. Fire rated vapour control layers are now being specified. Specifications will invariably state standards for fire classification and require evidence of compliance.

Acoustic performance is another crucial performance marker. This is especially the case in mission-critical sectors where a steel deck, rather than concrete, is specified to keep the capital cost down and help speed up the construction of the building.

Regarding robustness and weather protection, there is a risk of wind uplift that could cause severe damage to the roof. Hail strikes in some locations and accidental damage by flying debris pose a risk to roof systems that use roof membranes. Roof access is pivotal in data centres and buildings with many building services that require regular maintenance placed on the roof. The use of a rated insulation will often lower compressive strength causing a design challenge.

The demand for roof system performance in mission-critical settings is increasing, and roof/cover boards are becoming a crucial part of a roof system. We will now consider what the benefits of roof and cover boards are.

How can specification of roof and cover boards enhance the performance of low slope roofs in mission critical buildings

There are various types of roof and cover boards available on the market. Glass fibre mat faced gypsum boards, such as DensDeck® Roof Boards, are fast becoming the preferred choice for specifiers because of performance, and contractors, because of the installation benefits. They are light and relatively easy to manoeuvre on site and install in situ without specialist tools when compared to other non-combustible products such as cement boards.

DensDeck® Roof Boards can be used as cover boards, placed above the insulation layer and below a roof’s waterproofing layer. Alternatively, they can be used as roof boards, on top of the roof deck and below the insulation. The performance benefits of each position are slightly different, but in mission-critical buildings, they are often specified in both placements.

DensDeck® Roof Boards can be installed as fire resistant roof cover boards. They have been tested and classified to have an A1 reaction to fire in accordance with BS EN 13501-1. When installed as roof boards, they protect the roof from internal fire spread. The board’s function is to help shield the roof from external fire sources.

Specification of DensDeck® Roof Boards can help mitigate the risk of damage to flat and low slope roof from adverse weather events. They can be used as a strong and firm substrate for mechanically fixed membranes. The gypsum cover boards with mat facers increase the material compatibility with various adhered and part adhered roof membranes. The addition of glass mat facers also encourages even spread of adhesives for much improved bond. As 90% of all data centres use adhered roofing systems, specification of cover boards is critical to achieving maximum roof system performance.

DensDeck® Prime Roof Boards have been enhanced, with the introduction of EONIC® technology, to improve the vertical pull strength of both top and bottom glass mat facers. With the increase in the vertical pull strength, DensDeck® Prime Roof Board help to improve the wind uplift resistance of the roof build-up. Cover boards can also help protect the waterproofing membrane from hail strikes and flying debris that could otherwise penetrate through it.

Installation of DensDeck® Roof Boards means the cover boards can help improve the resistance of the often most expensive roof build-up component, the insulation layer, from compression that could compromise its performance. This allows for roof access by supporting the insulation layer as well as the membrane, the cover board can help mitigate the risk of damage caused by people accessing the roof for maintenance. The boards can withstand static and dynamic loads and are ideal for strengthening the roof build-up and reducing stress on the waterproofing membrane caused by heavy equipment such as heating, cooling, and ventilation (HVAC) or solar panels.

We already mentioned that some facilities emphasise the acoustic performance of the roof build-up. As is the case with fire performance improvements, the roof or cover boards can be installed in two positions within a roof assembly, and each will have a different impact on the acoustic performance. Positioned as roof boards directly on the roof deck, they help reduce noise transmission through a roof. To help with acoustic absorption, cover boards are often installed over the insulation layer. The exact design of the roof build-up and placement of the mat-faced gypsum board will reflect the specific acoustic requirements of the project. Acoustic testing will confirm that the roof build-up satisfies the design requirements.

Contact us to find out more about the benefits of DensDeck® Roof Boards for your mission critical project.