Masonry Magazine April 2003 Page. 28
SEALING
THE DEAL
After you've got a good cure on your wall, it just may be time to put a high-grade, clear water repellent on your project.
BY JENNIE FARNSWORTH
YOU'VE JUST FINISHED OFF THAT NEW MASONRY PROJECT AND YOU'RE STANDING BACK and admiring it. A finished work of art. Work of art, maybe, but finished? Many experts feel that it's not time to pack up your toolbox until you've applied a water repellent to the surface of the brick or block. We spoke with Jeff Erdly, President of Masonry Preservation Services, Inc., Past President of Sealant, Waterproofing and Restoration Institute (SWRI) and MCAA member, and he had plenty to say about the subject.
"You can take a wall that is well constructed and functioning, apply a high-grade, clear water repellent on it, and you can improve the performance of a good wall," says Erdly.
"I often tell clients that the time to put on a clear, water repellent is after we have repaired all of the deficiencies that make the wall leak. Once you have a wall that doesn't leak, there are certainly good arguments to apply a clear, water repellent. They can include, but are not limited to: protection of brick that doesn't meet severe weather grade; enhancing the ability to clean the wall down the road: and improving the appearance of the wall during wind driven rain events where it doesn't all wet out. There's a whole list of attributes that a high-grade, clear water repellent can bring to a correctly built, functioning wall.
"However, in our industry, when the wall doesn't work and the building leaks, the first thing that people do, or they run to for a quick and easy fix, is 'Gee, I'm going to put two coats of whatever on this wall to make it function. It just doesn't happen."
There are quite a few materials out there to choose from. Erdly says, "You want a material that, chemically, has a molecule small enough that it can actually penetrate the pore structure of the wall of the brick and really create that hydrophobic area back in the structure of the brick itself. We want our waterproofing not on the surface of the brick, where it's going to be scoured, worn away and degraded by UV light, but actually within the masonry."
Some types of water repellents that will penetrate the pores of the brick and block include silanes, siloxanes and silane/siloxane blends. These types of materials can help protect porous building structures against water and water-borne contaminants and damage, such as freeze-thaw, acid rain, and growth of algae or fungi.
"The chemistry behind those materials, their molecular size, and their ability to penetrate the pore structure are much better than the surface sealers that form a rather significant seal on the surface, like the acrylic resins," says Erdly. "I'm not qualified to give you the analyses on the different chemical make-ups; there must be 500 different mixtures and matches, everything from snake oil down to stuff you can't even pronounce, which claim to make a masonry wall work."
So are we talking about waterproofing or water resistant systems? Erdly has strong feelings about this.
"The whole idea of a waterproof masonry wall, in my opinion, is a fallacy," says Erdly. "In the real world it simply doesn't happen."
Terry Wallace, Director of Chemprobe, Tnemec Company's Masonry Protection Division, agrees. "Waterproof is way over used in the commercial end; it should probably be a term that is never used. I just happened to read something in one of the BIA publications, and they actually said that they do not like the word 'waterproof or even use the word 'waterproof because, in essence, we just don't have systems that are truly waterproof.
"The definition that we follow in the industry and that nomenclature can get people in trouble is that we manufacture water repellents or water resistant systems. What we like to say is that we are part of a complete building envelope water management system. Surface-applied water repellents being one component of that, proper design being another component, and proper construction procedures being followed and adhered to is yet another. Mostly we're talking about single-wythe construction, but there is no doubt that these same concepts would also apply to multiple-wythe construction. It is however of the utmost importance when you have the single-wythe construction."
So whenever you're laying brick, you should apply a high-grade, clear water repellent, even if it's cold out? "Absolutely not," proclaims Erdly. "You can't have ice crystals formed within the substrate you're trying to penetrate. If you're putting a clear water repellent on a wall, you need a wall where the surface temperature is at least 40 degrees. A lot of these materials require a catalyst to make them become hydrophobic. They have to get on the wall and they have to react with constituents in the assembly to "let the Genie out of the box, if you will. Applying clear water repellents in cold weather, you're just asking for all kinds of problems. Unless you're building it where the temperature never gets real warm.