Waterproofing Grades Explained


The British Standards Institute’s performance grades define the level of performance needed from the waterproofing. We’ll help ensure your project is Type A, B and C compliant using the four grade definitions.

Waterproofing Grades Type A with Ancillaries Waterproofing Grades Type B with Ancillaries Waterproofing Grades Type C with Ancillaries

Performance Grades

The British Standards Institute’s BS 8102:2022 (Code of practice for the protection of below ground structures against water ingress) classifies basement waterproofing into four separate performance related Grades – Grade 1a, 1b, 2 and 3.

The performance grades, as outlined by BS 8102:2022 define the level of performance needed from the waterproofing and this should be agreed in advance in conjunction with the client’s expectations.

For example, in some instances within a commercial or industrial setting, some seepage or dampness can be tolerated. However, within a domestic or residential setting, a completely dry environment needs to be guaranteed.


Seepage and damp areas from either internal and/or external sources are tolerable, where this does not impact on the proposed use of the below ground structure.


No seepage. Damp areas from internal and external sources are tolerable.


No seepage is acceptable. Damp areas as a result of internal air moisture/condensation are tolerable, though measures may need to be taken to manage this.


No water ingress or damp areas are acceptable. Ventilation, dehumidification, or air conditioning necessary appropriate to the intended use.

Types of Waterproofing

The same British Standard categorises the methods for below ground waterproofing into three different types.

TYPE A: barrier protection

Pre or post applied ‘barrier’ waterproofing materials

Type B: structurally integral

Structurally integral watertight constructions

Type C: drained cavity construction

Drained cavity construction

These different types of classification are designed to make a clear distinction between the types and combinations of basement waterproofing available dependant on the intended use of the structure.

The various methods of basement waterproofing are categorised as Type A, B and C and can be used as stand-alone methods or in combination with each other depending on the grade of waterproofing to be achieved, though each still must be designed independently of the other.

Waterproofing Grades Type A with Ancillaries

barrier protection

Type A waterproofing is defined and described as ‘barrier protection’ by BS 8102:2022.

This method refers to either pre or post applied external barrier systems such as Hydroswell BentoGuard Membrane and internal or external systems such as slurries, renders etc.

Waterproofing Grades Type B with Ancillaries

structurally integral

The British Standards Institute’s BS 8102:2022 goes on to define Type B waterproofing as structurally integral through the design and construction of the structure itself.

Typically, this would be reinforced concrete with an Admixture combined with BBA approved hydrophilic water bar such as Hydroswell BentoStrip 2.0 used within construction joints.

Waterproofing Grades Type C with Ancillaries

drained protection

Type C is defined by BS 8102:2022 as the management of any water ingress into a structure by collecting it into an incorporated drained cavity system within the basement structure itself.

This usually comprises a cavity drain membrane on the walls and floor designed to collect and direct water into a drained void which is then removed.

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Quality Assured Waterproofing

BBA Certificate 21/5917
BBA Certificate 21/5901

The construction industry uses a ‘best in class’ certification issued by the BBA (British Board of Agrement) to indicate high quality, experience and reliability within either a product or a company.

BBA status is highly regarded and trusted by all professionals within the construction industry.

All of our key systems including Xypex C-Series, Hydroswell BentoGuard Membrane and Hydroswell BentoStrip 2.0 have been awarded BBA certification.

Our single point warranty backed, comprehensive waterproofing service

In addition to our industry leading products, SMR provide a comprehensive service backed by years of waterproofing expertise and construction industry knowledge.

CSSW Qualified Design Team
In House 3D CAD
Site Service
Single Point Warranty including PI
Dedicated Training Facility

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