Elastomeric coatings are applied to roofs, walls, and structural surfaces for their flexibility, waterproofing, and UV resistance. Elastomeric polyurethanes bridge cracks and waterproof substrates like concrete and metal. When properly installed, these coatings provide long-term protection and durability. However, defects can occur if surface preparation, application, or environmental conditions are not controlled.

Understanding these defects and how to prevent them is essential for contractors, inspectors, and asset owners. The following outlines common elastomeric coating defects, their causes, and prevention methods.

For decades, waterproofing systems have been built with one goal in mind: performance. But in today’s built environment, performance alone isn’t always enough, aesthetics matter too. That’s where Color Shield™ Topcoat comes in. Color Shield is a next-generation, two-component polyaspartic topcoat designed to deliver UV-stable, color-stable protection, without compromising the proven performance of CIM waterproofing systems.

Waterproofing membranes, waterproofing coatings, and waterproof linings are terms that can be applied to a wide range of products.  They can be cold-applied liquid products, hot-applied products, peel-and-stick membranes or thermoplastic linings to name a few.  All these products provide a good barrier to water when used under proper circumstances.  So, why do so many installations leak?

 Left image: reinforcing fabric installation on a roof

 

The presence of leaks can almost always be attributed to poor attention to the waterproofing details, including:

Coatings fail to bond to concrete for two reasons:   

1. Lack of sufficient surface profile.
2. Moisture in the concrete

Today, most coating manufacturers require concrete substrates to be dry (<5% moisture content) with low vapor transmission (< 3-5lbs per 1000 sq. ft./24 hours) before applying most types of membranes. This applies to both new and existing concrete substrates, although each may have its own set of moisture-related problems. For example, a 90-year-old poured-in-place partially buried concrete tank may face an entirely different set of circumstances from a newly constructed concrete slab with a steel tank mounted on it. Ultimately, the concrete needs to be dry prior to coating.

Aggregates are commonly used in conjunction with liquid applied coatings to provide a combination of the following:

• Protection:
• Light colored aggregates lower deck temperature extending the life of liquid coatings

• Non-skid surfaces:
• For foot traffic
• For automotive and other traffic
• Exit areas for pond, containment, and other sloped surfaces

• Energy costs:
• Lighter colored aggregates will reflect solar energy, whereas dark-colored liquid coatings will absorb heat. Aggregate will reduce coating temperature by as much as 70 degrees on a hot summer day.

• Provides a rough surface in which to enhance the bond of other paints, coatings, and topcoats (asphalt, concrete, tile applications)
• For compliance with ANSI 118.10 IAPMO Approval for applications such as plaza and balcony decks.

Tired of going back to repair waterproofing membranes which weren’t installed properly during the first application?

Time spent planning ahead of time and using proper application procedures can be some of the most important aspects of getting it done right the first time.

Costs associated with repair or “re-do” work can add up quickly. As an example, take a decorative fountain project.

Suppose the installer did not take the proper time and attention into preparing the surface for liner installation. The liner was installed on top of the poorly prepared surface. 

Work continued with the installation of decorative stone on top of the liner. The result:  the fountain looks great, but is it ready to be put into service? Probably not, because important preparation steps were ignored at the beginning.

Environmental conditions can wreak havoc throughout all phases of a coating application.  To maximize the longevity and performance of the coating, we need to monitor environmental conditions, utilize proper testing equipment, and maintain daily field logbooks to stay on the path to coating success!

Environmental Effects on Coatings

Environmental conditions refer to the air and surface temperatures, relative humidity, dew point, and wind speed; each of these can negatively impact the coating if not properly monitored. 

• Air and surface temperatures are the first conditions to check when assessing the potential for effects on the working and curing time of the coating as well as moisture formation on the substrate. It is equally important to verify that temperatures arein line with the manufacturer’s product recommendations. 

 

 

 

 

 

 

 

 

 

 

Experienced contractors know that documenting the activities of a coating, lining or waterproofing application can be the key to a successful job.  The purpose of documentation is twofold:

The first thing that usually comes to mind when people think of profiling concrete to prepare for coating application is sandblasting. Unfortunately, this method may not always be practical. Sandblasting is loud and can create excessive dust so other alternatives are sometimes required.

When applying elastomeric coatings over concrete, abrading the surface is almost always required. This prerequisite to abrading the surface is twofold:

1) Remove the “laitance” or weak surface layer of the concrete.
2) Create an anchor profile for the coating to adhere.

The requirement which most coating manufacturers use to measure the roughness of the concrete surface is the Concrete Surface Profile or “CSP”. CSP was developed by the International Coating Repair Institute (ICRI) and is divided into 10 classifications often depicted by molded rubber comparison chips (CSP 1-10) as shown below.

Polyurethanes are used to make products with properties ranging from soft flexible foams such as memory foam mattresses, to rigid foams used for house insulation. They can be made into soft rubber as used for skateboard wheels or into very hard enamels as used in modern automobile paints.

 The range of properties can be quite wide, just by changing the chemistry a little, but there's a problem. The traditional chemistry uses materials that have an affinity for water. For applications such as fountains, pond liners, waterproofing, water and waste water tanks, roofing — where long term or constant immersion is an essential requirement — that affinity for water will lead, eventually, to the product swelling or even failing. The reason is in the chemistry, itself. Here’s why.