Converting damp basements and other spaces below ground level into dry rooms can be a cost effective and highly rewarding way of extending a home or utilising space within an existing property.
Many members of the Property Care Association specialise in the provision of waterproofing systems that are employed to upgrade existing basement rooms, waterproof new buildings or convert damp, unused spaces below ground into dry habitable rooms.
Structural waterproofing below ground is a highly specialised operation and must be undertaken by contractors and designers who have the requisite levels of skill, understanding and experience. Failures resulting from inadequate specifications or poor workmanship can be very costly. PCA members who specialise in structural waterproofing are able to work with the client to design a suitable waterproofing solution.
Waterproofing in existing underground structures is usually undertaken by applying waterproof membranes to the inside walls and floors or by using drained cavity technology.
Waterproofing techniques are defined in BS8102, the British Standard for “Protection of structures against water from the ground”. Members of the PCA must demonstrate an understanding of this standard and the Association’s code of practice for underground waterproofing. The PCA also requires that surveyors providing guidance on waterproofing must demonstrate their competence by gaining the “Certificated Surveyor in Structural Waterproofing” (CSSW) qualification.
The two types of waterproofing system commonly used in existing structures are:
Adhered waterproof membranes or “Type A” waterproofing systems (as defined in BS8102) are commonly multi coat renders, cement based coatings, bituminous paints or epoxy coatings. This form of waterproofing provides an unbroken barrier to water. These systems are applied to clean walls and floors and are usually protected and held in place by floor screeds, renders, plasters or other “loading coats”.
Cavity drainage systems or “Type C” waterproofing usually utilise pre-formed high density drainage membranes, channels and sumps. These are designed so as to direct any water entering the structure back out in a controlled and managed way.
Typically cavity drain membranes are installed to the walls and floors these direct water into drainage channels. The channels then allow water to be directed to sumps or drains so that it can be removed safely from the building.
Members of the PCA who specialise in structural waterproofing are able to consider the nature of the building and the clients design requirements to ensure that the correct method of waterproofing is selected and executed to the highest standard.