Here in Scotland water is one of the worst enemies of masonry. If allowed to penetrate, it can cause serious damage to the masonry structure, not to mention that it encourages the development of efflorescence, mold growth, joint and cavity steel corrosion as well as the loss of insulation value.
Due to the potential risks that water presents, the application of water repellent coatings should be considered as a part of masonry’s maintenance.
Basically, water repellent coatings keep water from penetrating the surface of masonry structures, but allow water vapor to enter and leave through the masonry “pores.” Because they are usually transparent, they do not create a film on the surface, thereby preserving the original appearance of the substrate.
It should be noted, however, that water repellent coatings should be chosen and applied with great care. This is because some products may actually hasten the deterioration of masonry structures rather than protecting them against the effects of water and changing weather conditions.
Thus, if you are planning to purchase a water repellent coating for your masonry surface, you might want to consider these tips to arrive at an informed choice.
Asses the type of masonry you have
Take note that water repellent coatings for masonry come in five different categories: acrylics, silicones, silanes, siloxanes and blends (a mix of silane and siloxane).
Each of them has unique properties, provides varying levels of protection, and may only be compatible with certain type of substrates. Because of this, it is important that you first analyze the type and condition of the masonry that you are dealing with as this will help determine the kind of water repellent coating you should use.
Accordingly, many experts recommend choosing breathable coatings that have high water vapor transmission—the amount of water that can evaporate on the face of the masonry.
Coatings that are not breathable will only trap water and soluble salts that may affect the integrity of the structure and may also cause cosmetic flaws like efflorescence and soiling.
Test product samples
Assuming you are aware about the kind of water repellent that suits your needs, it is recommended that you select about five water repellents for testing. Test each of them on the inconspicuous areas of your masonry. At the most, you want a water repellent coating that does not leave an undesirable wet, dark or glossy film on the surface.
A word on water repellent application
Once you have chosen a good water repellent coating for your masonry, keep in mind that it will not be good enough if you apply it incorrectly. A water repellent coating should only be applied after all the necessary repairs are done on the masonry.
That is, patch up cracks or voids and repoint damaged joints if needed. You should also consider the weather as this can affect the water repellent’s ability to protect your masonry. If you apply the substance during cold weather, you are asking for all sorts of problems to appear on your masonry.
This article was contributed by Ericka, an avid writer who regularly contributes content for McIntyre Masonry, a premiere stonemason Glasgow company.
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