Low slope roof build up

Low slope roof build ups are designed with a pitch between 10° and 30°. They are generally specified for domestic extensions where a traditional pitch of over 30° could block windows on the floors above or the views from surrounding buildings, limiting access to daylight. Low pitch roof build ups are a great alternative to flat roofs or for larger commercial applications.

Low pitch roofs are in many cases specified because they are often aesthetically the best option. They also cost less than traditional roofs as they use less material and are quicker to install. Specialised materials are available for this type of roof build ups to improve drainage capabilities.

What are the benefits of low slope roof build up

• Low installation cost
• Ease of access
• Low maintenance
• Ideal for installation of solar panels and rooftop gardens

What are the benefits of DensDeck® Roof Boards for a low slope roof build up?

The most important consideration of low slope roof build ups is drainage, especially if the roof needs to accommodate runoff from another roof above it. Due to gravitational forces, the water on a lower pitch roof travels downwards at a slower rate.

There is an increased risk of water collecting in pools, and the water could find its way through the waterproofing layer. As a result, the sublayers, including the often-expensive insulation layer, can be compromised and water could eventually penetrate the building envelope.

DensDeck® Roof Board cover boards are an ideal substrate for a stronger bond with the waterproofing membrane and they can also protect the membrane from damage caused by debris or hail penetrating. The same level of protection extends to the insulation layer, as the cover board prevents compression caused by foot or vehicular traffic or the weight of the plant on the roof. In commercial low slope roof build ups, cover boards and roof boards also significantly improve the acoustic performance of the roof system.

Key benefits of DensDeck® Roof Boards for low slope roof build ups

• Bond strength
• Fire protection
• Acoustic performance
• Extended roof design life

technical data & downloads

DensDeck® Prime Roof Board
Thickness (mm)6.4 (¼ inch)12.7 (½ inch)15.9 (⅝ inch)
Length (mm)243824382438
Width (mm)1219


Datacentre construction has a unique set of demands on the building envelope performance. The roof system must be robust and waterproof. Any moisture penetrating through the building envelope could cause service disruption with considerable commercial impact or even damage the expensive equipment. Specification of fibreglass mat face gypsum cover boards is ideal for both new datacentre projects and roof renovations that seek fast project delivery times and exceptional building performance.

Heritage buildings

Conservation and refurbishment of roofs for heritage buildings demands attention to detail. They often use roof coverings made from traditional materials, making installation more time and labour intensive.

Heritage roofs may have areas that are difficult to access, posing a challenge when it comes to the installation and the performance of the roof system. Cover boards are specified to make roof refurbishment easier. They also help increase the building performance of traditional, heritage buildings.

Museums & libraries

Roofing systems for museums and libraries have the important function of protecting valuable collections and creating a safe, comfortable space for the public visiting the facilities. Museums and libraries often combine traditional heritage buildings and striking modern extensions.

This allows architects and designers to blend high performing heritage roof refurbishments with modern green, metal, solar panel roofs, roof terraces with parapet systems or a fusion of the various roof types. Cover boards are a crucial part of these roof build ups capable of enhancing their performance and extending their design life.


Airports, hangar and maintenance buildings, car parks and other buildings in the aviation sector present their own set of challenges. These projects have intensive schedules and once finished, the highest level of building performance is expected to keep passengers comfortable and safe.

The performance enhancing capabilities of fibreglass mat face gypsum cover boards are ideal for specification in the aviation sector.


The construction of biotech centres must overcome a very specific set of challenges. These buildings fall within the critical sector and the expectation is that their roofing systems must be very robust.

Specification of fibreglass mat facer gypsum core cover boards enhances the performance and longevity of roof systems for biotech centres. It can also target improvement in specific areas of building performance, as required by each project.

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