Street smarts

Chris Hodson of the trade association Interpave discloses how precast concrete paving can help to meet planning requirements while adding kerb appeal to a development.

The use of segmental paving to create a hard surface can be traced back over 6,000 years, and precast concrete paving continues this tradition today. But, unlike extracted materials such as stone and clay, precast concrete block, flag, kerb and related paving products are fully engineered and manufactured under modern, controlled conditions. This consistently ensures accurate joint size, colour, texture, slip/skid resistance, and other performance characteristics. Because of this, precast concrete paving can offer a unique level of predictability with consistent, trouble-free performance over the longer term.

Planning requirements

Precast concrete paving helps to meet local and national planning demands for high quality external space, improving appeal to house purchasers as well.

For example, the National Planning Policy Framework (NPPF) seeks safe and accessible developments, containing clear and legible pedestrian routes with attractive public space, and design codes are used to deliver high quality outcomes – covering landscape, layout, materials and access. Intended to augment the NPPF, guidance such as the Manual for Streets continues to inform the development of local policy and design codes for external public spaces.

Summarised from these guidelines, the key requirements for paving materials include visual appeal and the ability to deliver distinctive local character, with a capability for visual or tactile differentiation between distinct areas. Paving should be durable and maintainable, with reliable product supply, safe and accessible to all, with consistent slip and skid resistance characteristics and good drainage to avoid standing water. Sustainability – in the widest sense – is essential, as is compatibility with Sustainable Drainage Systems (SuDS).

Visual appeal

Precast concrete paving is uniquely placed to satisfy these demands. Distinct modular units with varied colours, textures and shapes break up areas, providing a visual interest not possible with formless materials such as asphalt. In recent years, manufacturers have transformed this concept, moving away from the simple, regular patterns and colours of the 1970s and 1980s. Today, precast concrete paving offers an extensive palette of styles, shapes, colours and textures can be used to meet current urban designs, matching – and often exceeding – the visual qualities of materials such as stone.

In terms of design potential, pigment technology today allows for a much wider choice of colours, ranging from vibrant or muted tones, to mixes that can emulate other materials. Surface treatments can also be applied to paving blocks, flags and kerbs to give different textures, some exposing the inherent aggregates. Surfaces can be honed for a flat finish, polished, shot blasted to look weathered, or tumbled for a more rugged, naturalistic appearance. Combining these attributes with the range of shapes and sizes available enables designers to select paving styles, whether traditional or contemporary, that can enhance any development.

Sustainable Paving

Precast concrete paving from reputable manufacturers is often demonstrably sustainable in every sense. As well as a low environmental impact, with such products frequently achieving a host of ‘Green Guide’ A+ and A ratings, precast concrete paving may be to be locally manufactured, making a vital contribution to the economy and community.

Local material sourcing and product supply is also a key element, and equivalent paving products shipped into the country bear a substantial CO2 emission load over those locally supplied.

Concrete block permeable paving is a key SuDS technique, helping in the fight against flooding and pollution. It can also supply a controlled flow of clean water to other SuDS features for amenity use in the landscape or recycling. It is one of the most space-efficient SuDS components available and does not require any additional land-take, making it an ideal solution for urban areas. In fact, it can handle runoff from roof drainage and adjacent impermeable surfaces around double its own area.

Easily reinstated

The ongoing availability of a complete range of products and accessories in a single, predictable material is also essential over the long-term. Organisations working within the UK’s framework of established standards and regulations can easily achieve this aim. Precast concrete paving can be simply reinstated following excavation works, to access services for example, leaving minimal evidence with any replacement product readily available. It is also worth remembering that all these benefits of precast concrete paving are often available at an economic cost – in both initial and whole-life terms.

The key to cost-effective design with precast concrete paving products is to optimise their modular nature, by dimensioning areas to minimise cutting and combining compatible products to avoid it. As with any construction operation, detailing of edges, insertions, level changes and junctions within paving should not be left to site operatives, but resolved by designers.

Inevitably, installation quality is key to the success of any project and Interpave, along with its sister association Interlay, supports NHSS30: ‘The Quality Management of the Installation, Maintenance and Repair of Modular Paving’. It assures the installed quality of modular paving products by providing an industry benchmark and a foundation for ongoing improvement, while highlighting the importance of a suitably trained workforce.

Chris Hodson is consultant to trade association Interpave