Flat roof waterproofing

The challenge

Top-floor flats had leaks that came back with every rainy season. The roof had been patched repeatedly and the patches no longer helped: the original membrane was spent and the falls were not draining properly towards the outlets.

The solution

The whole build-up was stripped back to the slab, new falls were formed in lightweight concrete and a polyolefin membrane was laid with insulation in an inverted roof arrangement. Outlets were enlarged and safety overflows added. The roof is now walkable, with floating paving on pedestals that gives access to the membrane without breaking anything out.

Services involved

• Refurbishment and conservation