Lawrence Hall - Restoration of a unique roof space in London

Lawrence Hall is a Grade II listed property. A brown and brick stone building sits in front of a concrete framed hall featuring high vaulted ceilings with circular skylights made from Georgian wired glass.

The existing warm roof construction had reached the end of its serviceable life causing water ingress throughout the building.

A new warm roof system was installed featuring Wecryl 230 for the waterproofing layer. This high-grade PMMA-based resin is cold applied with a Weplus fleece reinforcement resulting in a durable waterproofing membrane that is highly flexible and permanently weather resistant.

The thixotropic version of Wecryl 230 was used to waterproof around the large circular rooflights situated on three levels of the building. With a thicker consistency and rapid curing time, this PMMA resin was ideal for the vertical upstands. 

Wecryl 230 was also applied around the windows at all roof levels combined with Wecryl 815, a highly flexible, fibre-filled waterproofing product for sealing minor penetrations.

Running the length of the main hall is a considerable amount of glazing with small upstands. After removing the existing asphalt from below the windowsills, the substrate was repaired before applying Wecryl 810, a rapid curing putty, which can be used to quickly fill small cracks and joints, and to smooth out uneven areas.

A small high-level terrace area was also stripped and replaced with a new warm roof and protective cement board. The waterproofing membrane was installed with a trowel on wearing layer and topped with quartz sand to increase slip resistance.