What is Type A structural waterproofing?

The British Standard for Waterproofing, BS 8102:2022, defines three 'Types' of waterproofing:

• Type A Barrier Protection where a barrier membrane, liquid or sheet, is applied to the structure, either internally or externally.

• Type B Integral Protection: the structure itself is the waterproofing.

• Type C Drained Protection: an internally-applied drainage system collects and removes the water that has managed to pass through the structure or the waterproofing as described above.

This article explores the requirements for Type A waterproofing systems using Newton's HydroBond system as an example.

Newton 403 Hydrobond is a high performance External Waterproofing Membrane, providing a Type A waterproofing solution.

Type A barrier waterpoofing

An example of high-performance Type A waterproofing is Newton's Hydrobond system which is designed to be applied to the outside of the structure.

The system is either pre-applied below the concrete raft / slab and wall building line, or post-applied where conventional formwork is removed to expose the outside of the basement walls. 

Once installed, and depending on the type of structure it is applied to, the combination of selected products within the HydroBond System can provide a continuous barrier around the full extent of the structure.

Depending on the products employed, Type A waterproofing systems can provide protection against water and gases.

The HydroBond System can be specified to provide protection against both groundwater and ground gases such as radon, methane and carbon dioxide, making it the ideal solution where protection from any or all of these elements is required.

View the products within the HydroBond System

The table below details which combination of products can be used together, dependent on project requirements.

Please note that in some cases, a combination of HydroBond 2K-Flex and HydroBond SA or HydroBond SAGM should be used together, especially where:

Depending on the many considerations within BS 8102, some of which are highlighted above, the Newton HydroBond System can provide high-performance protection against groundwater and ground gases, either as a standalone system for the lower grades of waterproofing performance or in conjunction with other Newton waterproofing systems where enhanced protection is required.

Design considerations for waterproofing systems

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The waterproofing design should be undertaken by a qualified waterproofing designer who is ideally included as part of the project design team. A geology and hydrology assessment should be carried out.

Groundwater removal

The removal or drainage of groundwater should only be considered if it is safe and practical to do so, which in most cases will be where the basement structure is built within sloping ground.

Where there is no slope to allow for successful movement of the groundwater away from the building by gravity, and the ground investigations show a high-water table or an undetermined water table, it should be assumed that the ground could be fully saturated at some point in the future and that a full height of water pressure should be expected.

Waterproofing design

The waterproofing design should consider how the structure is to be constructed and from which materials, as well as the intended use of the below-ground space and the internal floor and wall finishes. Advice regarding the required 'Grade' of waterproofing can be found within the current version of the British Standard:

• Grade 1 - Some seepage and damp areas are tolerable, dependent on the intended use.

• Grade 2 - No water seepage is acceptable. Damp resulting from condensation is tolerable and measures to control this should be considered and may need to be added at a future date.

• Grade 3 - No water ingress or any dampness is acceptable. Heating, ventilation, and humidity control/extraction is required to ensure an environment that is appropriate for the intended use of the space.

For more information, click here to view Newton's Structural Waterproofing Overview article.

When to consider multiple forms of waterproofing

The waterproofing design should consider multiple forms of waterproofing where:

• The assessed risks are deemed to be high

• The consequences of failure to achieve the required internal environment are deemed too high

• The required Grade of waterproofing performance is Grade 3

Where multiple forms of waterproofing are deemed to be required, and depending on the form of structure to be waterproofed, the Newton HydroBond System can be used in conjunction with the following systems to deliver the required enhanced levels of waterproofing performance:

• Internal Type A - Newton HydroSeal System

• Type B - Newton HydroTank System

• Type C - Newton CDM System

Newton waterproofing services

Newton Waterprofing Index (NWI) specification tool

The Newton Waterproofing Index is a unique specification tool in the construction industry, providing specifiers and designers with a scoring system in order to accurately assess the level of risk and potential success involved in a waterproofing design.

Design service

Having maintained our Professional Indemnity (PI) Insurance for waterproofing designs for over 20 years, Newton is also able to support specifiers with our bespoke waterproofing design service, backed by our insurers and our PI policy.

Find out more about our design service

Technical support

Our team of dedicated technical staff are all trained Certificated Surveyors in Structural Waterproofing (CSSW) and able to assist with your project, from design to quality assurance visits and on-site training via our specialist site support team.

Contact Newton Waterproofing on 01732 360095, or complete the enquiry form opposite to contact a member of the team.