Lift Pit Waterproofing

Leaking lift pits is a common problem. They are usually below the floor slab level and often below the subsoil drainage system, therefore they can be subject to hydrostatic pressure. They are usually small, externally tanked in difficult, often wet and confined working conditions. It is good practice to incorporate a small sump or low point in the base of the pit from which water can be pumped in the event of water ingress.

RIW LAC is a bitumen solution usually applied to the external face of the pit & walls, in conjunction with RIW Double Drain and a sub-soil drainage system. A high level of workmanship is essential to ensure all corners and angles are reinforced and sealed with RIW Sheetseal 226. RIW LAC is not suitable for use beneath the pit; RIW Sheetseal 226 or RIW Structureseal should be used in this case.

RIW Flexiseal is a flexible polyurethane lift pit waterproofing membrane with colour-coded coats for quality control. Additional reinforcing strips and corner fillets are not necessary, simplifying the application, which is therefore less likely to fail due to inadequate workmanship. RIW Flexiseal is an ideal choice of membrane for masonry construction. RIW Protection Boards or RIW Double Drain should be used to prevent damage from backfill operations. As a liquid applied material, it is not suitable for use below the floor.

RIW Toughseal is a polymer modified epoxy membrane that can be use in waterproofing lift pits when applied to the internal faces of a lift pit to enhance the performance of watertight construction by incorporating an oil resistant damp proof membrane. RIW Toughseal is available in grey, which improves the level of lighting for lift maintenance.

RIW Structureseal is a sodium bentonite composite sheet that is the ideal choice to externally tank a concrete lift pit because its self-healing waterproofing qualities are activated by ground water. It is simple to install and is usually laid into the excavated ground or against sacrificial shutters. Protection boards are not necessary and the product can be used in waterproofing lift pits in conjunction with other RIW membranes when required.

RIW Cementseal and RIW Cementflex are high performance cement based waterproof coatings that can be applied internally to prevent leaking lift pits in both new and existing lift pits. The coatings will resist up to 100m of negative water pressure, and can be used without the need for an internal loading coat, which is an advantage over other internally applied systems, when space is limited.

(Identify the most appropriate RIW product(s) for your specific application from the text above and click on the product icon on the right to access the product page for more information and downloadable data sheets).

For more information about lift pit waterproofing please contact the RIW Technical Department.