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Premier Guarantee highlight the importance of perimeter drainage channels to ‘type C’ basement waterproofing systems

Our technical team have recently observed some cases of basement waterproofing systems being installed that are not in accordance with the Building Standards. The following information should assist with this type of installation.

BS8102 (Waterproofing Regulations) defines the following methods of basement waterproofing that are accepted:

-          Barrier protection (Type A)

-          Structurally integral protection (Type B)

-          Drained protection (Type C) 

All of the above methods require a certain level of both serviceability and maintainability to ensure the system continues to keep the basement waterproof over time. Type A and B arguably have fewer maintenance issues, however Type C requires more attention to help prevent the build-up of lime scale behind the membrane. This is usually in the form of a perimeter drainage channel in order to catch any lime and prevent blockage in the membrane beneath the floor.

Perimeter Drainage Channels allow lime scale to be cleared by either dissolving, flushing or using drain rods to ensure the waterproofing system functions for a long period of time. It is important to note that a maintenance programme should be complied with.

In order to comply with BS8102, the type C cavity drainage system must be accessible for servicing and maintenance, the best way to achieve this is by using perimeter drainage channels which must be maintained in order to prevent blockages. Failure to use this solution could result in the cavity drainage system failing to perform and in most cases, requiring a full system replacement. 


For more information on Substructures see Chapter 6 of our Technical Manual