A Danrae Group guide to negative waterproofing

View of the house under construction

Negative waterproofing is a term you may encounter on occasion. Whilst not used as commonly as standard positive waterproofing, there may be times when our team will recommend negative waterproofing, either during new construction or for civil, commercial, strata or government remediation projects.

At Danrae Group, we use negative waterproofing in very specific circumstances and most commonly in basement waterproofing, lift pits or other below-ground areas.

Our guide to negative waterproofing includes the differences between positive and negative waterproofing, and negative waterproofing techniques, benefits and best applications.

Waterproofing basement

What is negative waterproofing?

Our team often applies waterproofing membranes to rooftops or building facades. In these cases, where we install the membrane to the exterior face of a structure, it is termed ‘positive’ waterproofing.

Positive waterproofing is the standard type of waterproofing and most commercially available waterproofing systems are suitable for these external applications.

As the name suggests, negative waterproofing is applied to the internal or ‘negative’ side of a structure.

Generally, we opt for negative waterproofing for a very practical reason – ease of access. There may, however, be other occasions where we recommend negative waterproofing as part of a comprehensive waterproofing strategy.

Negative waterproofing may consist of a correction to the substrate for enhanced protection against water ingress, and/or we might utilise a negative hydrostatic coating as a final protective layer in your waterproofing solution.

Membrane Varieties and Method

Benefits of positive and negative waterproofing

Positive waterproofing works by preventing water from entering a substrate and waterproofing membranes can offer additional features such as resistance to chemicals, UV or extreme weather. Negative waterproofing does not prevent water from entering a substrate, but it has a specific advantage.

On completion of a waterproofing project such as a rooftop garden or balcony, the remedial process after membrane installation includes concreting, decking or landscaping. This means the membrane is sealed within the structure and we can only access it with a second remediation project to remove and then rebuild the layers above the membrane.

The obvious benefits to negative side waterproofing then, are access and cost. As it does not fully protect the substrate and may be susceptible to chemicals or ground contaminants, however, the optimum solution is often positive side waterproofing during construction and negative waterproofing for remedial projects.

Stock of paints

Negative waterproofing solutions

Negative waterproofing must be able to withstand hydrostatic pressure, and techniques include epoxy injections and cementitious coatings.

In preparing our waterproofing solution, we might also opt for acrylic or other additives that penetrate into the substrate, providing further protection.

Generally, negative waterproofing products are mineral-based, free of chlorides that might affect concrete’s inner steel reinforcement, resistant to high water pressure and able to penetrate a little into the substrate to ensure it is not pushed out of place by the force of external water pressure.

Man at the rooftop holding a paint roller

Comprehensive waterproofing services

At Danrae Group, our team is trained to work with every brand and every type of waterproofing membrane and product, so we have complete flexibility to provide you with the most cost-efficient and effective waterproofing solution.

Our comprehensive services include diagnostic, solution design, waterproofing, remediation and preventative maintenance, and because we have an in-house team of waterproofers and trades specialists, we take care of full project management… and guarantee our quality.

Please read more about waterproofing techniques, or to discuss all of your waterproofing options, please contact us.

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