Architectural visions of how completed urban regeneration schemes will look frequently form part of public consultations and early planning applications, with computer-generated images giving life to how designers imagine the street scenes will look. Often these projects are beautiful with large areas of paving linking commercial and leisure activities with transport hubs, housing and ‘centrepiece’ attractions such as fountains or garden areas. The aesthetics and performance of these areas are integral to their success and rightly considered early in the development programme. Yet, all too often the pedestal systems that form the unseen support to what can be hundreds of square metres of expensive and heavy paving are not given full consideration. So what do you need to consider?
Pedestals – the benefits
Pedestals are used to support paving or decking at street level or on roof terraces or balconies. There are a wide variety of products on the market, from entry-level fixed-height solutions to self-levelling, adjustable and heavyweight pedestal solutions. All provide a ‘floating floor’ with uniform, spirit-level flat surfaces and separate paving/decking from the base structure, improving drainage, protecting the surface beneath and avoiding the need for sand and cement.
For many specifiers and end clients, a huge benefit of using pedestals is quick installation, the ability to cope with complex shapes and pitches and ease of maintenance – flooring elements such as slabs and decking can easily be removed for inspection or repair and services can be run in the space beneath.
Selecting the correct system for a project depends upon its needs, complexity and weight of the paving. Consider if the site has differing levels, height thresholds or lightwells/roof windows/penetrations? For example, a roof deck may have blemishes or ridges where felt overlaps, or the thickness of paving slabs may differ slightly across a project. Both situations are perfect for self-levelling pedestals, which can also be used to create the required fall across a flat roof.
Adjustable pedestals with a self-levelling headpiece would, for example, neatly complete a ground floor area required to be flush with the doorway threshold of a house or building without compromising the DPC. When in doubt, specifiers and contractors are encouraged to refer to pedestal manufacturers for assistance with product selection; leading suppliers offer design software, layout tools and other technical support for clients unsure which pedestal system best suits their needs.
An easy way to spot hard landscaped areas supported by pedestals is to look for slim gaps just millimetres wide between pavers or decking strips. These gaps are formed when the slabs or decking are clicked into place on special lugs attached to headpieces. These lugs firmly hold the floor elements in position and the gaps facilitate drainage, with rainfall directed into established drainage channels beneath the hard landscaping, either at street or roof level.
This system also creates an opportunity to collect the rainwater for recycling.
Pedestals are particularly popular for roof and balcony projects because they require no penetrations of roof membranes (there are no mechanical fixings), protect the roof finish, are more lightweight than bedding into mortar and are a quick and cost-effective way to transform unused and unattractive flat roof areas into attractive, usable spaces. They are also future-proof as they can be lifted to allow quick and easy access to the roof deck, should an issue arise with it.
Challenges
Given that paved or decked public areas can be subject to high pedestrian traffic levels, it is really important to install a pedestal system that can withstand the required weight tolerance and elements long-term, offering suitable durability. It is a huge concern that we are seeing cheaper, inferior quality products enter the market which claim to be comparable to established, quality systems but which offer no independent testing, poor quality control, poor manufacturing provenance as well as doubtful proof of performance.
For Wallbarn, pedestals are our core product and a market sector we have more than 40 years of experience in. We are a market leader in the UK and have supplied projects around the globe, from the Canadian Arctic Circle to Australia, Dubai to Hong Kong, USA to Zanzibar, South Africa to Iceland. We know that failures can happen when an inferior product is installed. Not only is it expensive; it poses an untenable risk to the public. A good example is a city centre project we were asked to inspect following the partial collapse of raised paving over a roof area accessible to the public; a member of the public had been injured, and there was a water leak. On site, we lifted slabs around the affected area and discovered that the architect’s specification for quality pedestals carrying independent laboratory certification had been disregarded in favour of a cheaper alternative where the injection moulded plastic pedestals included a large proportion of chemical fillers leading to the product becoming brittle in cold temperatures and shattering. The contractor was held liable for the claim, which included a personal injury claim and major refurbishment/redecoration of the building. This is a stark example of what can go wrong and, while not common, demonstrates the inherent dangers in installing a cheaper product that does not offer clear evidence of proper independent product testing and certification or a track record of performance.
Conclusion
Suspended pedestal systems are a quick and cost-effective method of boosting a building’s footprint by helping to repurpose unused and unattractive flat roof areas as well as providing an equally efficient and low-maintenance support solution to large areas of urban paving. Given the investment that goes into these projects, it pays to get it right the first time.
