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Sealing and waterproofing products for concrete and masonry – what’s the difference?

Many consumers – and even some professionals – use the terms “sealants” and “sealers” interchangeably, but there is a difference. Sealants are typically rubberized coatings or caulks and create an elastic layer on the surface. Sealers, on the other hand, such as acrylics, urethanes, and epoxies, are either film-forming or penetrating, sealing the substrate internally.

There are dozens of products on the market these days which can cause considerable confusion for consumers looking to preserve and protect their interior and exterior concrete or masonry features. To help clear up matters, let’s take a look at the various major categories of sealing and waterproofing products:

Penetrating sealers include silanes, silosanes, silicates, and siliconates and are used primarily on exterior concrete surfaces subject to corrosion and freeze-thaw damage where a natural, matte finish is desired. Most products provide excellent protection against outdoor exposure conditions and are also breathable, enabling moisture vapor to escape.

Acrylics form a thin protective film on the concrete surface and are available in both solvent- and water-based formulations in a wide range of sheen levels. Acrylics provide good protection against water and chloride intrusion, but usually wear faster than polyurethanes and epoxies. Solvent-based acrylics generally perform better and enhance color better than water-based products for outdoor use.

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Sealing and Resealing Concrete and Masonry

The terms “waterproofer” and “sealer” are often used interchangeably when it comes to concrete and masonry coatings, but they are not the same things. Knowing the difference between the two can help contractors and consumers avoid problems down the road.

Waterproofers are generally made from rubber, plastic or a sealing agent. They’re designed to keep moisture both in and out, penetrating the pores of the masonry and expanding as it dries to become a part of the masonry, creating a continuous film.

A water sealer, however, is a repellent designed to cause water to bead up on a surface while allowing moisture vapor to pass through. Sealers are typically applied in such a way as to permeate the substrate, which is usually very porous, ensuring that the substrate is sufficiently covered. Water sealers can be applied with a brush, roller or sprayer. Only one coat is recommended unless the surface is extremely porous.

The idea that water can wreak havoc on masonry or concrete may sound strange, but constant exposure to water and especially winter freeze/thaw cycles can damage or destroy masonry surfaces in a surprisingly short amount of time.

For above-grade brick or masonry surfaces exposed to wind-driven rain or other weather elements but not subjected to hydrostatic pressure (the weight of a body of liquid pressing down on a surface), a water sealer fits the bill nicely. A sealer will satisfactorily protect the surface and maintain its original beauty. Waterproofers, on the other hand, are usually pigmented products that tend to change surface appearance.

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