The superb adaptability of a Sika-Trocal single ply waterproof membrane ensured its specification for a stunning new roof installation

In a challenge to industry norms, the Sika-Trocal SGK 1.5mm - traditionally a flat roof membrane – was applied to a pitched, lead-style mansard roof containing imitation standing seams. The installation formed part of a large residential development in Poole, Dorset. The town centre scheme, which occupies vacant space comprising two, three-storey blocks, was financed by social housing provider, Stonewater. It includes nine energy-efficient, one and two-bedroom affordable homes on a shared ownership and low-cost rental basis with associated parking, bin and cycle stores. 

For the mansard roof, the client required a lead-style effect and associated dormers in a material that was more cost-effective than lead, to suit their specification and budget. Sika-Trocal’s fully-bonded SGK system proved more than ideal for the task. The reinforced PVC waterproof membrane offers a durable solution for warm and cold roof construction. As well as supplying high tensile strength and superb resistance to mechanical installations, Sika-Trocal® SGK provides outstanding weathering and excellent flexibility in cold temperatures, which along with its easy-fit benefits; makes it the ideal membrane for exposed roofs.

Roofing specialists, Volsen, installed the SGK system. It was combined with imitation standing seams to mimic the mopstick effect of a lead roof. To complete the look, Volsen continued the Trocal over the dormers, completely encapsulating them in membrane; a cost-effective option compared to lead or cladding. This provided continuous waterproofing over the area and eliminated junctions between systems, which have could have led to future problems. This allowed cost savings for the client, as only one trade was required on site to complete the whole area.

The gutter profile was completed in powder-coated aluminium to the capping, fascia and soffits in a colour-match with the Trocal slate grey to seamlessly blend with the mansard roof. For thermal efficiency, 100mm-thickness Sika-Trocal INNOFix, foil-faced insulation board was laid onto the timber deck to create a warm roof. Sika-Trocal S-Vap 500E provided the system’s vapour control layer. As part of Sika’s all-round service offering, its technician made regular site visits to ensure quality and conformity throughout the installation. Such was the project’s success it was named ‘Highly Commended Best New Build’ at the 2019 SPRA Awards.

Thanks to the skills and experience of Volsen’s installers and the seamless, adaptable attributes of Sika-Trocal’s SGK system, the Poole development was supplied with a waterproofing solution that not only maintained the surrounding area’s historical aesthetic, it will ensure this much-needed social housing scheme will remain untroubled by the elements for years to come.