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Do I need waterproofing or damp proofing?

Water ingress and damp penetration can cause serious problems to a building. If you suspect that your property is suffering from any water related issues, the first thing to do is identify the problem. Whether you need waterproofing or damp proofing will affect the approach to solving your problem.

Consider the External Ground Levels

Problems can occur if the dampness is showing in a property with external ground levels that are higher than the internal floor level. In the example above, the moisture residing in the external ground is a contributing factor for the dampness already identified. The high ground could also be saturated enough for water to bear against the structure, creating a risk of water ingress.

Where high ground levels exist, it should be assumed that water ingress is a possibility. Therefore, a waterproofing system is required. Where there are no high ground levels a damp proofing solution is required.

To summarise:

  • If the external ground levels are lower than the internal walls (or if the external ground could be lowered) – a damp proofing system would be the recommended solution (Newtonite System for Damp Proofing).
  • If the external ground levels are higher than the internal walls, for example a basement or cellar – a full waterproofing system is required (Newton Cavity Drain Membrane (CDM) System).

Technical Details


Where the external ground is higher than the internal floor, and waterproofing is required, the recommendations within the British Standard 8102:2009 (Code of Practice for The Protection of Structures Against Water from the Ground) should be followed.

BS 8102:2009 is a design document used to inform the designer of the various methods of waterproofing available and to assist in the correct specification of those systems.

Grades of Waterproofing

The general principles for successful waterproofing are:

Decide on the end use of the space to be waterproofed. Depending on the desired end-use, BS 8102:2009 defines three Grades of internal environment. These are the level of waterproofing protection that is required for each one:

  • Grade 1 – Car parks, plant rooms (excluding electrical equipment), workshops – Some seepage and damp areas tolerable, dependent on the intended use.
  • Grade 2 – Plant rooms and workshops requiring a drier environment – No water penetration acceptable, damp areas tolerable, ventilation might be required.
  • Grade 3 – Ventilated residential and commercial areas, including offices, restaurants, leisure centres – No water penetration acceptable. Ventilation, dehumidification, or air conditioning necessary, appropriate to the intended use.

Once the internal Grade has been established; it is important to select a waterproofing system that is capable of achieving the required environment.

Newton Waterproofing Index

To assist the specifier in deciding on the correct waterproofing specification, the Newton Waterproofing Index (NWI) is a unique waterproofing specification tool. It has been developed to assess the ability of a waterproofing specification to successfully protect an earth-retaining or below-ground structure.

This assessment is based both upon the type of structure involved, and the type/s of waterproofing being used. The purpose is to give specifiers an accurate understanding of the potential success of different specifications and builds. It also helps to guide them through the myriad of different waterproofing products and combinations available in the market. Visually, this assessment is then represented as an NWI ‘score’ that can be used to judge each waterproofing specification.

quotation marks

“Guardian Preservation Services LLP would highly recommend Newton Waterproofing Systems. The products are industry leading and the technical information they provide is outstanding” Tim Herbert, Guardian Preservation Services.


A Word of Caution

With the above in mind comes a word of warning. It is common for people to question why they should have a full waterproofing system if they only have slightly high ground levels and/or there is no running water present at the time.

While we understand their reticence, BS 8102:2009 states that regardless of conditions at the time of survey, one should consider that water ingress will occur at some time in the future. It also suggests that as well as water within saturated ground we must consider the following as potential sources of water ingress:

  • fluctuating water tables
  • the future effects of climate change
  • temporary pockets of water
  • perched water tables
  • burst water mains

The consequences of installing a damp proofing system where a waterproofing system should have been installed can be serious and very costly. Choosing the wrong system can cause a high probability of water ingress and flooding. The resulting consequential loss can be devastating.

Not Sure What You Need?

If you are unsure if you require damp proofing or waterproofing products do contact us, we would be delighted to help.

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Our staff are able to provide guidance for projects of all sizes, whether you require some general advice about damp or waterproofing, or support with technical drawings and specifications.

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