Solar panel flat roof

Specification of solar panels on flat roofs is rising as we construct more energy efficient buildings that increasingly rely on on-site renewable energy generation. In the UK, the optimal angle for the installation of solar panels, also referred to as photovoltaic or PV panels, is 30-40 degrees. This is a challenge for PV panel installation on a flat roof. Stands or arrays are usually required to achieve an optimum installation angle.

There are typically two options for fixing the PV system onto a warm roof build up, ballasted or mechanical. Mechanically fixed systems are either fitted to the roof deck, requiring penetration of the roof covering, or are fixed via mounting plates that are welded onto the roof membrane. Ballast is used to weigh down the system. In some instances, instead of ballasted, a green roof can be considered. This would use the weight of the growing medium or another substrate to secure the solar PV panel assembly.

Warm or inverted roof systems can be used for roof mounted solar panel flat roofs. The difference is the sequence in which roof layers are laid. A warm roof places the insulation below the waterproofing layer. In an inverted roof system, the position of these two layers is reversed.

What are the benefits of a solar panel flat roof?

• Increased site source renewable contribution
• Effective energy source for any building type
• Safe and relatively easy to install
• Hidden from view

What are the benefits of DensDeck® Roof Boards for a solar panel flat roof?

Similarly for terrace roofs, green roofs and single ply build ups, the design of solar panels on flat roofs must consider the weight of the installation, drainage design and the type of fixings for the PV panel technology. Cover boards are recommended to add strength to the roof system and protect the insulation layer from compression and provide an airtight barrier that improves the acoustic performance of the roof system.

DensDeck® Roof Board cover boards are ideal substrates for a strong bond with the waterproofing membrane. They also protect the membranes from penetration by tools, gravel, or damage that roof traffic can cause.

Installation of cover and roof boards can help increases the fire performance of the roof system. Solar panels pose a fire risk and cover boards can be installed to mitigate this risk and protect the insulation layer in the case of a solar panel malfunction.

Key benefits of DensDeck® Roof Boards for solar panel flat roofs

• Dimensional strength
• Puncture resistance
• Bond strength
• 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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