We are often asked to explain the difference between waterproofing and damp proofing and why one solution would be more suitable than another...
If the dampness is showing in a property with external ground levels that are higher than the internal floor level - as shown in the example above - the moisture resident in the external ground is not only a contributing factor for the dampness already identified, but the high ground could also be saturated enough for water to bear against the structure, creating a risk of water ingress also.
Where high ground levels exist, it should be assumed that water ingress is a possibility and so a waterproofing system is required. Where there are no high ground levels a damp proofing solution is required.
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)
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 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.
The general principles for successful waterproofing are:
Decide on the end use of the space to be waterproofed. Habitable Grades are defined within BS 8102 as:
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
Select a waterproofing system capable of achieving the required internal environment
To assist the specifier in deciding on the correct waterproofing specification, the Newton Waterproofing Index (or 'NWI') is a unique waterproofing specification tool, has been developed as a means of assessing 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, as well as helping to guide them through the myriad of different waterproofing products and combinations available in the market. Visually, this assessment is then represented as a NWI 'score' that can be used to judge each waterproofing specification.
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. Whilst 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, and 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, with a high probability of water ingress and flooding. The resulting consequential loss can be devastating.
If you are unsure if you require damp proofing or waterproofing products do contact us, we would be delighted to help.
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.
Newton Specialist Basement Contractors (NSBC) are an elite group of professional structural waterproofing and damp proofing specialists who work in partnership with us to provide clients with the best products, design and installation.