Internal Cavity Drain Basement Waterproofing System

Internally-applied Cavity Drain systems such as Oldroyd Xv are a popular method for waterproofing of new and existing basements.

This waterproofing system works by diverting any water entering the basement structure towards a sump and pump (Sentry Sump System). The Oldroyd Xv drainage membrane is fixed to the walls using special sealed plugs. These plugs also allow plasterboard to be fixed over the system using a wooden batten or aluminium frame system.

Cavity Drain waterproofing systems can be fast to install. In contrast to internally-applied cementitious tanking systems they do not require extensive surface preparation.

Cavity Drain basement waterproofing systems are dependent on the basement structure providing “primary resistance” to water ingress. This is acknowledged in BS8102 which states that where cavity drainage is to be used “the outer leaf of the exterior wall should be capable of controlling the quantity of water that can pass through it, in order not to exceed the drainage capacity of the system.” For this reason internally applied cavity drainage systems are often combined with the use of an externally applied primary waterproofing system – see internal/external combination waterproofing system. In refurbishment projects the resistance of the wall structure might need to be upgraded – (e.g. by patch application of Vandex Unimortar 1) prior to the installation of a cavity drainage waterproofing system such as Oldroyd Xv.

Regular maintenance of the sumps and drainage channel are essential for the long-term success of any basement waterproofing system based on cavity drainage.

Related CAD drawings

Preview	Description	DWG	TCW	PDF
	Standard cavity drainage (Type C) detail showing a perimeter channel incorporating Aquadrain into which Oldroyd Xv directs incoming ground water. Finished with a floating timber floor and Fastframe Dry lined plasterboard wall.
	Basement installed with Oldroyd Xv to walls and floors incorporating a Sentry Sump System and screed floor.
	Perimeter drainage detail incorporating Aquadrain where it is not possible to form a channel in the slab. Closed-cell insulation is used to build up the floor level to allow for a screed or timber floor finish.