Basement Waterproofing

Waterproofing a basement

Damp cellars and wet basements can be converted into dry, useable living spaces providing a suitable basement waterproofing system has been installed. As well as adding valuable space to your home, extending your living area can increase the value of your home by as much as 130-175% of the basement waterproofing project cost.

The choice of basement waterproofing system depends on the structure of the building, the condition of the basement walls and floor, the surrounding ground conditions and the intended use of the dry basement.

Code of practice for basement waterproofing

Biocraft designs its basement waterproofing solutions in accordance with BS8102, the code of practice for protection of structures against water from the ground.

BS 8102:2009 – the code of practice for the protection of below ground structures from water from the ground, defines three types of waterproofing systems. Type A, Type B and Type C. Any of these or a combination of two or more systems may be specified in a structural waterproofing project.

TYPE A basement waterproofing

This comprises of various categories of barrier system that are applied to vertical or horizontal concrete and masonry. It includes fully bonded systems such as TWS-EX100. This is a very effective self-adhesive sheet membrane with unique selvedge for fast and secure seal on all side edge laps. An easy to install water vapour barrier, it’s often used on foundations, basements, roofs, lift shafts and pits. It also acts as a barrier against radon, methane, carbon dioxide and other ground gases.

Liquid applied systems such as TT vapour membrane are a versatile, ready-blended waterproof coating which also acts as a barrier against methane and carbon dioxide.

Cementitious systems such as TT55 is a cement ‘tanking’ system and is highly effective as a damp proof membrane for brickwork, concrete or any cementitious substrate.

TT55 ME is a flexible water coating for use where vibration or cracking is anticipated. TT Super is an ‘active’ formulation that migrates into the concrete to form a waterproof barrier but still allows the concrete to breathe.

TYPE B basement waterproofing

BS 8102:2009 is used for concrete waterproofing where the structure itself is constructed as an integral water resistant shell. The water tightness of a Type B construction is reliant upon using a concrete of low permeability and appropriate joint detailing.

TT Admix is used at the time of batching. The chemicals react with fresh concrete to actively seal the concrete itself against the penetration of water or liquid and to protect it from harsh environmental conditions. Shrinkage cracks are constantly and automatically resealed during a life-long active protection system.

CEMflex VB Plate waterstop is a weatherproof, galvanised steel plate that only reacts with the water within the concrete and is therefore ideal for use in ICF or twin wall installations.

Waterstop is a hydrophilic, ready-to-use waterstop which swells up to 350% when in contact with water.

TYPE C basement waterproofing

Defined in BS 8102:2009 as ‘drained protection,’ this is achieved by the incorporation of a drained cavity within the new or existing basement structure. Water is collected in the cavity between the external wall and the cavity drain membrane and diverted to a suitable drainage point.

BBA approved, P8 membrane is manufactured from tough, high density polyethylene and is impermeable to water, water vapour and radon gas. It’s an easy-to-use, high capacity drainage membrane typically used within the basement floor build up.

External basement waterproofing CDM

Double Drain is for external use and is designed to protect external basement walls from backfill damage. The filter fabric layer ensures soil can’t enter the membrane cavities to impede drainage – therefore reducing external hydrostatic pressure.