Costs: Liquid roof waterproofing systems | Features

Liquid-applied waterproofing systems
Specification options	Capital cost £/m²	Net present value for 60 years	Service life years
Modified bitumen
Liquid modified bituminous system, minimum 3 mm thick, surface reflective coat	40	141	Oct-20
Inverted roof: hot applied bitumen liquid membrane in two coats minimum 6 mm thick with reinforcement, protective sheet, insulation board, separation layer and 50 mm thick concrete paving slabs	131	131	60
Polyester-based system
Polyester-based system, minimum 1.5 mm thick applied in two layers with pigmented top coat. Third-party assurance for 20 years’ life expectancy	42	116	20
Polyester-based system, minimum 1.5 mm thick applied in two layers with pigmented top coat. Third-party assurance for 25 years’ life expectancy	48	113	25
Polyurethane-based system
Polyurethane-based system, minimum 1.4 mm thick two layers. Third party assurance for 15 years’ life expectancy	40	131	15
Polyurethane based system, minimum 2 mm thick, three layers. Third party assurance for 25 years’ life expectancy	50	114	25