Over the years we’ve seen it all – from stained masonry to damage from ice thaw. Read our helpful maintenance tips to learn more about how to care for your stonework.
Efflorescence literally means blooming flowers. In stonework, it refers to the white staining that appears on masonry that is subjected to moisture and the presence of mineral salts in solution. When the water evaporates, it leaves that white chalky, powdery residue.
The mineral salts can leach into the masonry from the ground if there is an insufficient moisture barrier between the masonry and the ground, or in some cases, from additives incorporated into certain mortars to make them more manageable in cold weather. Such additives do not cause efflorescence when used on masonry that is protected from ambient moisture from the ground or air.
Prevention: The quickest cure for efflorescence is to prevent excess moisture from coming into contact with the masonry – either from the ground or from the air. What isn't so simple is how you go about doing that. There are several ways to go about preventing excess moisture from getting into masonry and causing freeze/thaw damage or efflorescence.
Impermeable Barriers: One way to prevent excess moisture from reaching masonry is to add a waterproof vapour barrier to the side of the masonry that is in contact with moisture. This can be done with continuous plastic or polymer sheeting, waterproofing chemicals, or a combination of both sheeting and chemicals.
Drainage: Often, the quickest and most inexpensive solution is to ensure that water can drain away from the masonry. This can involve installing proper weeping tile to allow moisture to escape from between the ground and the masonry, or improving how water drains away from structures so it doesn't contact the masonry.
Removing Existing Efflorescence: Efflorescence isn't mould, so it can be removed with a stiff nylon (not wire) brush while it is dry (be sure to wear a proper filter respirator!).
Alternatively, you can use a mild solution of vinegar (2 parts) and water (10 parts) and a nylon brush. Dip the brush in the mixture and wipe the masonry with a circular motion. Rinse the area thoroughly with clean water.
At a certain stage, efflorescence becomes water insoluble, so water will not work to clean it. If you cannot brush it off, and water won't remove it, then you should consider hiring a professional to clean it using an acidic or EDTA solution. Be advised, if you try to use an acid-based product yourself, you could damage your masonry if you apply it improperly. Again, seek professional advice before any use of acid-based products.
Everyone knows that water is a powerful force. We see it every day in fast-running rivers that have gouged mile-deep wonders of the world like the Grand Canyon. We see how, when flood waters crest their banks and levees, water can obliterate entire towns and sections of cities in the blink of an eye. But those are only the most dramatic examples of water's power.
Water's true power is its ability to expand and exert gigantic forces when it transitions from a liquid to a solid in the form of ice. One study shows that the expansive powers of ice contained within a brass spherule could overcome a resistance of more than twenty-seven thousand pounds, or thirteen-and-a-half tons! So powerful is this expansion force that some science fair students theorized that ice "generators" that harness this force would be a viable source of alternative energy.
Stone masonry can withstand millennia of extreme weather, but only if water is not allowed to take up residence behind or between the stones – if it does, even the strongest, densest stone is no match for water's destructive expansion power when it turns to ice, or worse, when existing ice begins to warm up. When this happens, it expands more rapidly than when it initially freezes, and with great power.
Prevention is Key
Rain screen: In both man-made stone and real stone applications, we use specialty products to create what's referred to in the construction industry as a rain screen. With a proper rain screen behind the stone and above the home envelope, we create an environment that reduces or eliminates wetting due to gravity, capillary action, and wind pressure differences.
Proper mortar: In addition to the incorporation of a rain screen, we also use high-quality "Type N" cement, designed for our harsh climate and to minimize efflorescence. In natural block and brickwork applications, we use "Type S" cement.
Protective sealers: In addition, all stone can be finished with a protective sealer after the cement has dried. We prefer a high-penetrant coating. This coating is also low sheen, and it slightly darkens or deepens the look of the stone to give a richer and more appealing appearance.
On all houses, new constructions and renovations, we can use a sealing product prior to papering above window and door frames. This step will further prevent leaks and assist in moisture control.