TerraSmart® Rail Paving System

Not necessarily. Whether a double rail system is more expensive than a single rail system depends on the specific project requirements.

For larger, regular-format paving, such as 600 x 600 mm slabs, a single rail system can often be the most cost-effective solution. However, single rail systems typically lack the same level of system integration as a lattice-frame solution and are more heavily reliant on perimeter detailing and the quality of installation to achieve long-term performance.

For smaller format pavers, staggered layouts, or more complex paving patterns, the lattice framework created by a double rail system can deliver greater efficiency and may offer overall cost savings. The double rail system also provides increased flexibility for accommodating complex detailing, alternative surface finishes, and future design requirements.

Project costs are influenced by a range of factors, including the terrace layout, the shape and size of the area, and the paving type and format being used. As a result, there is no one-size-fits-all answer when comparing the two systems.

For the most accurate assessment, we recommend obtaining project-specific pricing for both options. This allows the most suitable and cost-effective solution to be identified before a final decision is made.

Not always. In many applications, a double rail system can provide installation efficiencies by creating a stable lattice framework that can be levelled and adjusted before the pedestals are installed beneath it. This approach can reduce the need to individually level large numbers of pedestals, helping to simplify the installation process.

Installation speed is influenced by a number of factors, including the experience of the installer, the size and complexity of the terrace, and any additional integrations or detailing requirements within the scheme.

While a single rail system may involve fewer components, a double rail lattice framework can often offset this through improved adjustability, greater installation flexibility, and a more structured approach to achieving a level finished surface. As a result, installation times should be assessed on a project-by-project basis rather than assuming one system will always be faster than the other.

The lowest achievable build-up height with the TerraSmart rail-lattice frame system is 45 mm from the substrate to the underside of the paving finish.

This ultra-low profile is achieved using the RST27 top rail (27 mm), DS15 lower joist (15 mm), and the ADC-0 low-height support cleat (2 mm+).

This configuration allows the benefits of a fully integrated rail-lattice support system to be utilised in areas where build-up height is extremely limited, making it suitable for refurbishment projects, threshold-sensitive details, and other applications where minimising construction depth is critical.

In addition, the RST27 top rail can be installed directly into the low-height support clip, providing further flexibility around challenging details such as upstands, parapets, and perimeter interfaces. In these situations, the build-up height can be reduced even further, achieving heights as low as 30 mm from the substrate to the underside of the paving finish, helping to overcome some of the most restrictive site conditions while maintaining the benefits of the rail system.

Yes, a rail-lattice frame system can be combined with a pedestal-only paving support system within the same project. This approach can be used to accommodate different paving types, unit sizes, build-up heights, or to optimise overall project costs by using the most appropriate support solution in each area.

The flexibility to interface between the two systems can be particularly beneficial on complex roof terraces and podium decks where project requirements vary across the space.

However, it is important to consider the transition between the rail-lattice frame system and the pedestal-supported paving area. The lattice frame provides a continuous, integrated support structure, whereas a pedestal and paving system consists of individual, independent supports. As a result, there is a greater potential for differential movement over time at the interface between the two systems.

For this reason, careful design and detailing of transition areas is recommended to ensure long-term performance and maintain a consistent finished surface across the project.

While the finished appearance of a rail-lattice frame system and a pedestal-only paving system may look very similar, the key differences lie beneath the surface and relate to performance, flexibility, and suitability for the intended use of the space.

A rail-lattice frame system is designed to provide superior rigidity, continuous support, and greater flexibility when dealing with complex layouts. It is particularly well suited to projects that involve varying paving sizes, intricate paving patterns, ramps, steps, or challenging detailing. The lattice framework also enables seamless integration with alternative surface finishes, such as artificial grass, resin-bound gravel, and wet-pour rubber, through the use of a dedicated baseboard support system.

In addition, the rail-lattice framework can be designed to accommodate higher design loads and is often the preferred solution for communal roof terraces, public spaces, and heavily used external areas where increased structural performance and long-term stability are important considerations.

Pedestal-only systems are typically best suited to simpler applications with straightforward geometry and limited interfacing requirements. They are commonly used on private balconies, small private terraces, maintenance walkways, and other areas with lower footfall and less demanding loading requirements.

Ultimately, the right solution will depend on the specific requirements of the project. The most effective way to determine the appropriate system is to follow the five-step design process outlined in The Art of Roof Terrace Specification, which considers factors such as loading, layout complexity, surface finishes, usage, and long-term performance requirements.

No. Our standard aluminium joists and top rails are supplied in a mill-finish aluminium as standard. However, where project requirements dictate, these components can also be supplied with a powder-coated finish.

If a powder-coated finish is required, this can be discussed during the design and specification stage to ensure the most appropriate solution is provided for the project.

Our steel pedestal components are protected by a high-performance zinc-nickel coating, which acts as a sacrificial layer to protect the underlying steel substrate, even in aggressive environmental conditions.

To validate their long-term durability, TerraSmart pedestal components have successfully undergone more than 3,000 hours of salt spray corrosion testing, demonstrating exceptional resistance to corrosion and weathering.

In some particularly challenging site environments, minor surface staining may occasionally occur. However, this is typically cosmetic in nature and does not affect the structural integrity, durability, or performance of the pedestal system, which continues to function exactly as intended throughout its design life.

Occasionally, light rust staining may be visible on pedestal heads or surrounding paving surfaces. In most cases, this is not caused by the pedestal itself corroding, but by tiny steel particles introduced during construction activities such as cutting, grinding or drilling nearby materials.

Rainwater can wash these particles through the gaps between paving slabs, where they settle on pedestal heads and other surfaces before oxidising.

It is important to note that:

• The staining is cosmetic only.
• The protective coating on the pedestal remains intact.
• The structural steel beneath remains protected.
• There is no structural or safety concern.

Yes. The TerraSmart rail-lattice frame system is inherently Euroclass A1 non-combustible, as it is manufactured from aluminium and steel components.

The system has been developed to support projects where the use of non-combustible materials is a key design requirement, including high-rise residential buildings, commercial developments, podium decks, roof terraces, and other external landscaped areas.

By utilising A1-rated aluminium and steel components throughout the primary support structure, the TerraSmart rail system provides designers and specifiers with a robust support solution that aligns with modern fire safety requirements while delivering the strength, flexibility, and durability needed for external paving and landscaping applications.

The TerraSmart rail-lattice frame system has been tested as part of a complete roof build-up in accordance with BS EN 13501-5 and has achieved a B_ROOF(t4) classification.

It is important to note that B_ROOF(t4) is a system-based fire performance classification, meaning the test result applies to the complete roof assembly that was tested, including the roof construction, insulation, waterproofing, support system, and surface finish. The classification does not apply to the TerraSmart rail system in isolation.

As roof build-ups vary from project to project, a project-specific assessment should always be undertaken to ensure compliance with the relevant building regulations and fire performance requirements. Where necessary, consultation with the project fire engineer and design team is recommended to verify that the proposed roof assembly satisfies the required fire classification.

The 2 mm shock-absorbent rubber gasket fitted to the head of the TerraSmart RST27 top rail is not classified as non-combustible.

However, under the Building Regulations, gaskets are generally exempt from the reaction-to-fire classification requirements. Specifically, Regulation 7(3), paragraph h, identifies membranes, seals, gaskets, fixings, sealants, and backer rods as exempt components when assessing compliance with the external wall and specified attachment requirements.

As a result, while the gasket itself is not A1 or A2-s1,d0 classified, its inclusion within the TerraSmart rail-lattice frame system does not prevent the primary support structure from being manufactured predominantly from non-combustible aluminium and steel components.

Where project-specific fire performance requirements apply, the overall roof build-up and relevant regulatory requirements should always be reviewed by the project design team and fire engineer to confirm compliance.