Why the CUR is so important for sustainable masonry

The CUR recommendations are still not widely known across the market. Yet these guidelines play a crucial role in safeguarding quality and sustainability within the construction sector. Since quality is a priority for us at BNL Group, we believe it is important to highlight these recommendations and what they mean within the building industry.

What exactly is a CUR Recommendation?
A CUR Recommendation is a guideline that sets out practical agreements and procedures to ensure clarity in execution and quality control within the construction sector. These recommendations are developed by experts and contain concrete requirements for the composition, delivery, and production of materials, as well as for the execution and quality assurance of the work. They meet the need for clear regulations in the field of masonry and pointing. The recommendation not only provides technical information about these disciplines but also defines the requirements that mortars and their application must meet to ensure a durable and high-quality result.

The goal? To create uniformity among all parties involved — from client to contractor and advisor — so the quality and reliability of the work remain guaranteed. A CUR Recommendation offers practical guidance, calculation methods, execution rules, and quality criteria that help prevent risks such as damage, cracking, or discoloration.

At BNL Group, working according to these guidelines is second nature. They form the foundation of our craftsmanship and ensure that the outcome is not only visually appealing but also technically durable.

CUR Recommendation 61B: Hydrophobing Masonry
An important part of the standard is section 61B, which focuses on hydrophobing (or impregnating) masonry. Hydrophobing literally means making the masonry water-repellent. By treating a façade with a hydrophobic agent, the surface becomes resistant to water penetration without losing its ability to breathe, keeping the masonry vapor-permeable.

Why is this so important?
Because water is masonry’s greatest enemy. Moisture penetrates the pores of the material, and when temperatures drop, frost damage can occur. Hydrophobing prevents efflorescence from developing. It keeps the façade drier, cleaner, and more resistant to weather influences and pollution. It also offers an insulating benefit because dry masonry retains heat better.

What requirements must the wall meet?
According to CUR 61B, the substrate must meet specific conditions before hydrophobing can take place:

• The façade must be clean and dry.

• The pointing and masonry must form a solid, unified structure.

• The moisture content of the wall must not be too high; a damp substrate can reduce the effectiveness of the product.

In other words: hydrophobing only delivers results when the foundation is sound. Repair first, then protect.

What requirements must the product meet?
The hydrophobic agent used must also meet specific standards:

• It must be durable and resistant to alkalinity (the natural pH of stone and mortar).

• It may not alter the appearance of the façade.

• It must penetrate deeply enough into the material to provide long-term protection.

• It must be vapor-permeable.

• And, of course, it must comply with the CUR 61B guidelines — independently tested and proven effective.

Craftsmanship with certainty

At BNL Group, we work with these guidelines every day. Not because we have to, but because we believe true quality begins with knowledge and precision. By adhering closely to CUR 61B, we ensure every project is technically sound, sustainable, and built to look exceptional for many years to come.

We don’t see hydrophobing as an extra step, but as an essential part of keeping façades beautiful for the long term and preventing any form of efflorescence. It’s the protective layer that keeps craftsmanship visible, season after season.