Cleaning New Masonry Buildings
Combinations of Materials Have Changed the Rules
Remember when guys worked on their car’s motors and changing spark plugs was easy? Then computers were added under the hood and things got way too complex. Same thing with cleaning masonry. Masonry buildings used to be easy to clean when they were constructed from one kind of masonry material. Then architects started designing facades with all sorts of masonry right next to each other. Suddenly, the art of cleaning got a lot more complicated. The rules for cleaning masonry have changed, so we thought we’d review them with you. Ignore them at the peril of your project’s budget.
Always Know Your Surface
Today, cleaning masonry is a specialized task that is often subbed out to a cleaning specialist. In those situations, it’s critically important that the specialty contractor knows exactly what kind of masonry materials have been used. “Since a cleaning subcontractor didn’t lay the materials,” says Mike Rafferty, president of Goedecke Company, “it’s vital that he asks a lot of questions to make sure that what looks like limestone isn’t actually a band of cast stone.”
The cleaner has to do his homework up front to identify the different types of substrates on the building rather than simply showing up and cleaning when the mason contractor calls. “If they don’t start asking questions until after they start cleaning, there could be a bad situation,” Rafferty cautions.
Test First, Then Clean
Most commercial construction jobs have a wall mock up panel in place. Although a panel doesn’t usually get as dirty as the building itself, it does furnish an excellent testing site for identifying the substrates used. It’s also an ideal vehicle for running preliminary tests on the various cleaners being considered.
Use the Mildest Cleaner and Dilution That Will Give the Desired Results
Manufacturers offer cleaning products with differing levels of acidic and alkaline content. Normally, there are three stages of strength to handle increasing levels of difficulty. “We always start with the softest, most mild product to see if it will give us the results we are looking for,”says Rafferty. “Then if we have to, we’ll make the dilutions stronger or we’ll move up to a stronger chemical. But our goal is to use the mildest cleaner that we can.”
Clean Early, Clean Quickly
The sooner the cleaner can begin the process, the better the chances are that a milder cleaner will get the excess mortar and dirt off. Although getting to the wall quickly is not always possible, it remains the goal to shoot for.
It’s preferable to get to a wall within seven to 21 days of completion. If there is an additive to the mortar or grout, it’s even more important to begin within seven days before the material becomes more cleaning resistant. With clay masonry, the cleaner should begin his task within 14 to 28 days. High rise construction brings another set of problems as it can take 56 days to get to the cleaning, which is then much more difficult to clean than it is at 21 days.
Use the Right Cleaner for the Job
To nail down the most appropriate cleaning product for a given material, Raffery recommends involving the distributor or the manufacturer of the cleaning products under consideration. “The manufacturer will take a concrete or brick unit and conduct lab tests to fine-tune the decision as to the most appropriate cleaner,” Rafferty says. “Then when the material is delivered to the job site, there will be a pallet tag attached specifying which cleaning product to use.” For example, since Prosoco products– which Geodecke carries–will be used to clean the massive Ameristar project, Geodecke sent the brick to Prosoco wheretests were run to determine the mildest yet most effective cleaner to use.
Never Clean with Muriatic Acid
The Masonry Institute has been warning against cleaning with muriatic acid for years. Now it’s encoded in the new cleaning rules, and for good reason. Muriatic acid is actually a form of hydrochloric acid. It penetrates back into the masonry almost as quickly as water and may cause staining as it works its way back out. A proprietary cleaner may contain acid, but it is combined with wetting and soaping agents that keep it on the surface where it can clean effectively and then be easily washed off.
Those are the new cleaning rules. In addition, the basics below still apply.
Don't Spare the Water
A power washer is ideal because it will put between six and eight gallons of water on the wall per minute, far more than you can get from a garden hose. In hot
weather this is especially important because it takes a high volume of water to effectively pre-wet a wall and keep it wet before the heat can evaporate the water. In addition, a good power washer can’t be beat for effective flushing.
Clean Top to Bottom and Keep Those Lower Areas Wet
While working from the top, be sure to keep lower areas wet to avoid streaking and extra expenses to correct the problem.
Follow the Safety Precautions in the Literature
Learn from the mistakes of others. Wear the recommended protective clothing and apply the product as directed. Protect non masonry surfaces on the building, and don’t forget to protect bystanders as well as cars in the area of the cleaning.
In Cold Weather, Follow the 40 and Rising Rule
Don’t clean masonry unless the temperature is 40 degrees and rising, a precaution that provides a margin of safety against the water freezing. While there may be pressures to take a chance when the thermometer is in the 30s, resist them.
Cleaning masonry has become an increasingly sophisticated art. The combinations of different kinds of masonry on wall elevations and the development of new cleaning materials have made mastery of the art ever more demanding. Still, when a masonry project is completed and cleaned correctly, no other building material can match its sheer beauty.