Background
Cambridge Roofers were appointed by Princebuild Limited to refurbish the main flat roof at The Trinity Centre, Cambridge Science Park, Milton. The existing roof covering had weathered over time, with visible surface contamination, moss and debris build-up, and redundant flashing fragments left over from previous repairs. Rather than a full strip-out, the brief called for an adhered single ply overlay system, providing renewed waterproofing performance while working with the retained existing roof build-up.
The Challenges
Overlay systems place particular demands on the existing roof covering, since the retained substrate has to be sound, stable and properly bonded before a new membrane can be adhered over it. The roof needed to be thoroughly inspected and cleared of loose debris, vegetation and surface contamination, and any localised areas of loose, blistered or unstable material identified and made safe before installation could begin. Working across a large, fully open roof area also meant careful sequencing of the membrane laying and welding to maintain a weathertight surface throughout the works.
Cambridge Roofers’ Approach
Work began with a full inspection and preparation of the existing roof, clearing loose debris, moss and redundant material and checking that the retained covering was adequately bonded and dry enough to receive the new system. Localised areas of loose or unstable material were cut out and made safe, and adhesion trials were carried out to confirm compatibility between the existing roof and the proposed Sika adhesive.
Sikaplan SGK-18 fleece-backed PVC single ply membrane was then adhered across the main roof area using SikaRoof Adhesive-500, with all side laps hot-air welded to form a continuous, fully bonded waterproofing layer. Perimeters, upstands, rooflight kerbs and penetrations were detailed using compatible Sikaplan detailing membrane, pre-formed corners and coverstrips, with Sika termination bars and counter flashings installed to secure and weather all exposed edges. On completion, an electronic leak detection test was carried out to verify the integrity of the new membrane before handover.
The Works in Progress
Existing Roof Condition
The aerial survey shows the condition of the existing roof before works began, with visible surface staining and debris across the covering.
Close-up of moss and surface contamination on the existing roof covering
Redundant flashing fragments and debris cleared from the existing roof during preparation
Perimeter Detailing
Termination bars and coverstrips were installed at the roof perimeter to secure and weather the edges of the new membrane.
New single ply membrane installed with termination bar detailing at the roof perimeter
Close-up of termination bar and coverstrip detailing along the roof edge
Completed Roof
The finished roof provides a continuous, fully welded single ply membrane across the whole roof area, restoring watertightness with a back-to-back Sika manufacturer warranty.
Completed Sika SGK single ply membrane roof at The Trinity Centre
Wide view of the completed single ply overlay roof at The Trinity Centre
Conclusion
The refurbishment at The Trinity Centre delivered a fully welded, watertight single ply overlay system across the main roof area for Princebuild Limited, restoring the performance of the roof without the disruption of a full strip-out. The completed installation was verified with an electronic leak detection test and is backed by a Sika manufacturer warranty for the new waterproofing system.