Although primarily designed to waterproof basements, the range of Delta products were used at ground level on a semi-detached property in Hertfordshire that suffered from severe flooding. This is not the first contract where the Delta system has been selected for ‘Flood Recovery’ and Delta has long been highlighting the economic and speed of application benefits for the products in such situations.


After the flood at the Grade II listed property in Long Marston, restoration experts DJ Hutchings of Towcester was called in, and – in turn – they called upon the services of Peter Cox … a company that has made use of the Delta range over many years. Peter Cox were chosen because of their experience in this type of work, and a survey carried out by one of the company’s experience surveyors showed that flood water had entered the building and caused horrific damage internally.

The surveyor consulted with Delta technical experts to come up with the installation solution. The householders are looking forward to returning to the property in the knowledge that the Delta system allows fast reoccupation thanks to the installation which had been carried out by a Delta approved installer.

Work includes the full strip-out of all wall finishes and the solid floor on the ground floor. Mass underpinning is taking place to all the external walls. Included in the materials supplied by Delta Membrane Systems is the MS500 range – an 8mm studded membrane that will be applied to all ground floor walls. These studs create a drainage path – allowing up to 135 litres/minute/metre of incoming water to be drained – well in excess of the likely demands. MS500 is made from 0.6mm virgin thick high density polyethylene.

The new floor slab will incorporate Delta MS20 – an hdpe membrane with 20mm studs that offer an impressive compressive strength rating of 150kN/m2, and high capacity drainage to easily cope with heavy demands. Typically, it is used in applications where extra drainage capacity is required, such as deeper structures or where a larger flow rate is likely … so it easily copes with this particular installation.

In line with the considerations of BS8102:2009, a network of serviceable 100mm underground
pipes is laid throughout the oversite and turned up 90 degrees through the new concrete slab. These are protected by a Delta puddle flange and cut off level with the slab positioned at 12m2 centres. This aids for fast collection of groundwater that was notable rising up through the slab due to the high water table.

This network of maintainable pipes are connected to two Delta Dual V3 sumps and then pumped away from the property. The sumps are able to evacuate any ground water at a rate of 8 litres per second. Two battery back-up systems will be installed with the new Delta AlertMaxx high level alarms.

Delta also supplies the Köster collection of waterproofing applications. On this project, three of the products from an extensive range have been selected. These include Köster NB1 which is an ‘active’ crystalline slurry that will be used and applied between the underpinning stalls or interfaces to create a watertight seal between all these critical joints. This material along with Köster Repair Mortar Plus will also be applied at the areas where the walls meet the floors to act as a first line of defence. Köster Quellband hydrophilic waterbar has been deployed which will be used between the slab and the wall underpin junction to form a watertight seal.

In addition to the internal “Negative side” waterproofing and protection, a positive approach has also been adopted with the use of Koster Deuxan 2C externally on the “Positive side” of the structure. This is a two-coat polymer modified fully bonded material applied to the underpins backed up by Delta Geo drain Quattro drainage and protection layer.

Case Study Results

The range of products from Delta Membrane Systems is well known to contractors involved with the renovation of damp, dingy basements, and to those creating basement areas in new-build products.

Using the products for the refurbishment of areas adversely affected by flooding is not new to Delta, and the company sees this as being a market sector that would really benefit in terms of time and cost.

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