Waterproofing

Maintaining Your Boundaries

by Kathy Danforth / Published Mar 2014

Location, location, location isn’t just a real estate issue. Water and dirt are essential to life, but entire industries are devoted to preventing their entry and spread indoors. The fight against water invading homeowner space begins with site engineering and building design and continues through the building’s life with roofing, sealants, caulking, paint, waterproof membranes, and various logistical arrangements to usher precipitation away.

As the waterproofing materials age, replacement is an expected consequence. Earlier failure, though, must be caught to prevent the mold, corrosion, deterioration of finishes, and destruction of materials that misguided water can cause. “If waterproofing materials were not specified or installed properly, they can be prone to early failure,” notes David Karins with Karins Engineering Group. “Anything that makes the application more complex, such as window openings, corners, or a junction of different materials, makes a breach more likely. Manufactured chemicals are fairly reliable though, from time to time, there can be a factory issue with a product.”

“Sealants may have inadequate adherence due to poor application, either from operator error or the weather during installation,” observes Stan Swaysland with Swaysland Professional Engineering Consultants, Inc. “They are susceptible to failure if the substrate is wet or dirty, or the sealant is not mixed properly. Wall cracks often occur at joints in a stucco finish because of movement, shrinkage of the stucco over time, or delamination in the stucco finish that allows water to enter. Penetra-tions through the wall typically are a problem area, and fasteners for hurricane shutters are a common source of leaks.” Swaysland advises, “Buildings should be painted on a regular cycle. In the painting process, cracks should be repaired and all joints resealed. If you reseal every time you paint, that’s adequate, as usually the joint sealants last as long as the paint.”

Swaysland describes a renovation at a Miami Beach condominium involving water intrusion at the windows. “The building is probably 50 years old, but the windows were installed after Hurricane Andrew. We investigated and determined that the windows were too small for the openings, and the gap between the frame and the concrete structure was not properly filled and waterproofed. Eventually, all the windows were going to develop leaks. We devised a waterproof system from the frame outward about eight inches. All the loose and cracked stucco was removed, and we applied a three-coat proprietary waterproofing product to adhere to the metal frame and wrap around to the wall. New stucco was applied on top to blend in.”

Daniello explains, “Water intrusion into concrete will cause any reinforcing steel to rust. When steel rusts, it expands many times its original size and exerts a pressure of up to 10 psi and causes the concrete, which is usually not more than 3,000 psi in strength, to crack open. As the rust progresses in the structure—such as balconies, beams, or columns—supports become weaker and may fail.”

Karins recounts a water intrusion scenario at Ft. Myers, also involving a failure of replacement windows. “This was an older building, and when they replaced the windows and coatings 15 years ago, they didn’t do enough; they needed to take out the finishes around the windows also. Also, the walls were frame rather than concrete, and the impact-resistant walls they installed were heavier, causing the walls to sag. We were able to install impact-resistant windows with a different configuration.”

Leaks in roofs have the potential for some of the most expensive consequences. “A roofing leak is costly because of the cascading effect of water running through the building,” Karins notes. “Roofs have warranties of 5–20 years, and you may be able to get 25 years,” according to Swaysland. “Roofs develop leaks prematurely typically due to lack of maintenance or damage caused by people on the roof puncturing a membrane. Proper maintenance involves sealing pitch pans, coating flashings, and recoating of some systems.”

Frequent inspection and repair of the building envelope to halt water intrusion before it damages other components is the first line of defense. To facilitate water speeding away from your vulnerable surfaces, surfaces should be kept clean and drains clear. Also, Karins recommends utilizing the ubiquitous force of gravity to direct water away when possible. “Instead of relying on coatings and sealants, you rely on gravity to direct water to an impervious surface and away from the unit. You see this at work in a thatch roof made with just palm leaves. That’s what flashing, clapboard siding, or shingled siding is all about—using gravity, which doesn’t wear out.”

Water Intrusion Into Concrete

Concrete in decks, balconies, walkways, garages, and planters often fails as a result of movement of the substrate, failure of expansion joint sealant systems, or eventually deterioration of the waterproof membrane. Lou Daniello with Daniello and Associates, Inc. notes, “Moisture seepage usually gives tell-tale signs such as a white, slimy film or mold appearing in the area. In concrete, the first sign is usually small cracks that appear. If they increase in size, that is usually an indication of rusting steel inside, which is referred to as spalling.”

According to Swaysland, “Most of the labor involved is removing the overburden—tile, concrete, sand, pavers, or grass—to get to the waterproof membrane and structural concrete surface. I think everybody knows concrete restoration is an expensive and disruptive problem that causes a financial and emotional hardship to many homeowners.”

Daniello explains, “Water intrusion into concrete will cause any reinforcing steel to rust. When steel rusts, it expands many times its original size and exerts a pressure of up to 10 psi and causes the concrete, which is usually not more than 3,000 psi in strength, to crack open. As the rust progresses in the structure—such as balconies, beams, or columns—supports become weaker and may fail.”

To help preserve the concrete, Daniello advises, “Puncturing any waterproof areas should be avoided. However, if installation of items such as shutters, railings, or sunshades on balconies or walkways is required, it is important to pre-drill the attachment rather than shoot or try to screw the attachment into the substrate. This is similar to trying to put a screw or nail into hard wood such as oak. If it is not pre-drilled, it will create small cracks in the wood; the same is true for concrete. Once the attachment hole is pre-drilled, the hole should be filled with sealant before the attachment is installed to seal the surrounding area and prevent moisture from seeping into the substrate.”

The cost of properly repairing a concrete deck can lead communities to a quicker fix, which is unlikely to succeed. “If you have a 20,000 to 40,000 square foot pool deck, the cost to remove the overlying slab, clean the structural material, apply waterproofing material, and put down a protection course, drainage mat, and sand or pavers can run $35–$75 per square foot, depending on the extravagance of the new design and the demolition needed. That can run $1,000,000–$2,000,000 per deck; the board will say that’s too much and someone may sell them a coating on the top slab for $200,000. Most likely, it’s not going to work,” Swaysland remarks.

Signs

Signs of water intrusion are usually obvious, though finding the source or the extent of the invasion may be less clear. Tests for determining if there is water in an area include infrared photography to see any change in temperature caused by water, spraying water or creating a pressurized chamber to watch for water penetration, covering a floor with waterproof material to observe any condensation, and use of surface or probe moisture meters.

Most waterproofing materials, and especially waterproof membranes, have undergone considerable improvement over the years. Karins notes, “New coatings and sealants are developed all the time. One new coating described as self-cleaning is hydrophobic, so the water beads up and diverts both the dirt and water away. Polyurea is a rapid-curing material used on parking decks and ramps that cures instantly so the area can be opened to traffic immediately. It has a new set of challenges since it cures instantly and is very unforgiving, but it works from the waterproofing point of view. A new high-tech solution uses energized rods in below-grade parking structures to repel the ionized particles in water.”

In making decisions and pursuing a course of action, Karins cautions, “You have to be careful to get advice from people who are selling advice rather than a product or project. There’s a feeling that the manufacturer provides the warranty, so why shouldn’t they specify the product? But, some manufacturers have lines they want to push to make a profit. Our engineering specifications require approval from the manufacturer as to whether it’s the appropriate product, so the manufacturer will weigh in.” Swaysland comments, “Most of our work involves building permits, so communities are required to have plans and specifications from a professional engineer for restoration or repairs of a structural, load-bearing component. But even if it’s a project such as painting that doesn’t require a permit, many communities like an engineer involved to prepare plans and specs, pre-qualify contractors, ensure contractors are bidding apples to apples, observe work in progress for conformance to stand-ards, advise the owner on technical aspects of the contract, and monitor payments.”

Karins points out, “If there is any warranty problem, the manufacturer and contractor will point fingers at each other, and the building will be left with its hands in the air, with the choice of filing a lawsuit or starting over. If a professional engineer is watching the installation, it enhances the probability it’s done right. Good contractors feel a consultant is a big advantage; they like to have someone else looking over the workers’ shoulders. The owners never want a bad job, but they’re relying on the guy hanging on the side of the building wanting to leave on Friday afternoon to do the work right. The more eyes, the better it is for the contractor, the manufacturer, and the owners.”

Water is powerful and not to be ignored—a principle that residents of Florida face again and again. To keep water at bay requires quality materials, proper installation, regular inspection, maintenance, cleaning, and repairs to forestall major replacements. When the big project comes, though, Karins reminds associations, “It’s always less expensive to do it right the first time than to do it wrong and replace it.”