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Solving the challenges of terrace retrofit projects


A challenging project to retrofit a Class A fire-rated decking system to the balcony of a city apartment with floor-to-ceiling curved glass windows and multiple levels has demonstrated the technical competence of Wallbarn’s substructure and decking solutions.

Timber decking mounted on timber bearers required removing from the balconies of the duplex London apartment and replacing with the selected Class A decking, Wallbarn’s Exadeck porcelain solution.

As is normal with many retrofits of this nature, the full extent of what lay beneath the outdated timber decking wasn’t fully known until it had been removed. And, with two levels of irregularly shaped terraces and a connecting staircase to replace, the project was complicated even before the strip-out revealed a roof deck with multiple levels and unexpected upstands.

A complex substructure utilising a range of Wallbarn products onto which the high-quality rectified Exadeck porcelain decking could be laid was provided by the Wallbarn design team, utilising MetalPad D adjustable height pedestals connecting to aluminium rails/joists. Both box rails and I-Plus beams were used due to very varied height thresholds.

The lowest height pedestals were fitted to 20mm box rails whilst in other areas the 100mm high I-Plus beam was fitted to itself and mounted onto larger MetalPad D pedestals. Using MetalPad D in conjunction with the I-Plus and double box rails offered a distinct advantage; the profiles of these rails fit neatly between the lugs on the pedestal headpiece, ensuring a secure fit without the need for mechanical fixings. This design allowed the decking system some flexibility, permitting slight movement in the rails for optimal performance. It also speeded up installation.

To further complicate the project, the Exadeck was to be laid on a diagonal plane to the building so the top layer of aluminium rails needed fixing at this angle to allow decking fixing clips to be mounted at right angles to the rails. Connector brackets were used where rails met to add structural strength and stability.

Exadeck’s profile allows hidden wing clips to be fitted to hold the boards in place and provide an even drainage gap between each. importantly, the boards are ‘rectified’ during manufacture to ensure complete flatness, uniformity and straight lines across all planes with no risk of curling, bending or changes in thickness/width. The under surface is also completely flat so they sit securely on the rail surface and do not rock.

The variety of rail heights and type meant Wallbarn could accommodate complicated requirements to deliver a high-end, fire-safe, finish.


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