Selecting a Waterproofing Application Method - Hand vs Spray Applied

Posted by Maribeth Taylor on Nov 15, 2021 10:30:00 AM
Maribeth Taylor
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Illustration of a person applying waterproofing coating on a concrete slabWith many varieties of elastomeric coatings on the market, it should be no surprise that there are many different application methods to consider. So, how do you choose the best plan for your next project? 

This article will focus on polyurethane, cold, fluid-applied, elastomeric waterproofing coatings. These products can be hand-applied using a brush, roller, or squeegee or with specialized spray equipment. The application method is often predicated by project conditions that influence the contractor's ability to apply the material as a uniform coating at the required thickness.

Project Conditions

Before the project starts, it is essential to review product literature and project details. The coating manufacturer's product literature (commonly known as technical data sheets -TDS, product data sheets, application guides, and so forth) contains all the information on the best surface preparation, application conditions, and application techniques. And don't forget to document your environmental conditions throughout the application process! Also, by reviewing the project scope, staging, and special requirements, you can address any potential challenges that may influence the application ahead of time.

Application Methods

Every detail of the application process will impact the results and performance of the coating system. 

Common considerations include

  • the type of construction material receiving the coating,
  • the size of the space,
  • substrate conditions (horizontal, vertical, overhead), and
  • overspray concern.

Polyurethane-based elastomeric coatings are applied by hand or with properly configured spray equipment. 

Hand Applied

Most contractors prefer to hand-apply coatings on small- to large-scale projects. This method effectively achieves uniform coverage, allows for detail on transitions, and avoids overspray on unwanted areas. Here are three types of equipment used when hand-applying coatings:

  • Rollers -- Use rollers when you need a thin film of the coating material. When applying cold, fluid-applied membranes, use a phenolic core, short nap roller. Helpful hint: Back-rolling helps to maintain a uniform coating thickness and minimize runs and sags. 

CIM-EMT-Roller--ApplicationImage: CIM EMT Roller Application

  • Squeegees -- Squeegees have sturdy neoprene rubber blades with flat or notched edges. Notched squeegees are readily available in 20 and 60 mil sizes. The blades help to ensure smooth and even coverage of the coating on horizontal surfaces.

CIM-800-Squeegee-ApplicationImage: CIM 800 Squeegee Application

  • Brushes -- Brushes are commonly used on flat surfaces, such as walls, floors, and beams, and work well to detail penetrations, transitions, and any hard-to-reach areas. 

IMG_1699Image: CIM 1000 being applied by a brush 

Spray Applied

On large-scale projects and those with a lot of vertical or overhead space, the use of plural component sprayers, air-assisted airless sprayers, and other spray machines can expedite the coating application. Using these types of equipment requires having a skilled operator. Before, during, and after application, equipment must be monitored and checked for precise material flow rates to maintain the correct mix ratios for the coating to cure properly. It is critical to test the spray equipment, troubleshoot any problems, and establish a spray pattern before starting the application. Also, proper cleanout is crucial to prevent material curing in the equipment. 

Be aware! Not all sprayers are capable of spraying elastomeric coatings. Contact your coatings representative for further information.

A properly configured air-assisted airless sprayer or plural component sprayer can apply elastomeric coating onto large surface areas where the concern for overspray is minimal. Spray equipment is considered for projects with large vertical walls and overhead space and jobs with a vast amount of CIM Scrim, such as those found in secondary containment dikes and reservoirs. It's essential to note elastomeric coatings are not the same as paints; they do not spray like paint. 

There are two types of spray equipment commonly used:

  • Plural-component sprayers 
    • Premixing of components not required
    • Creates an airless pattern that minimizes runs and sags
    • Effective for overhead spray applications
    • Reduced crew size as compared to air-assisted airless spray systems
  • Air-assisted airless sprayers 
    • Low pressure/high volume configuration
    • Use of hopper-fed, cart-mounted pumps for maximum efficiency
    • Pole guns aid in minimizing fatigue
    • Require separate regulator and shut off valve for the pump and atomizing air

CIM membrane is not recommended for use in standard airless and conventional spray machines. 

Helpful Tips When Spray Applying

  1. Selecting a fan-shaped tip versus a round-shaped tip will produce a more uniform coating.
  2. Back-rolling can be combined with spraying to ensure uniform coating thickness and work the material into the substrate pores.
  3. Contact the manufacturer for written instructions.


Image: Applying waterproofing coatings with spray

Regardless of the application method, it is essential to routinely verify the coating's thickness and recoat over any thin spots in the membrane where you took a measurement. 

Wet Film Micron Gauge

Image: Wet Film Gauge


Coating applications can be demanding, so having a clear understanding of the coating and equipment manufacturer's recommendations, addressing potential project challenges ahead of time, and choosing the best-suited application method for the project will set you up for a successful application. 

By utilizing specially trained applicators with the knowledge and skillset in elastomeric waterproofing systems, you will get the job done right the first time. 

CIM Industries offers factory-trained applicator programs throughout the calendar year. There is an expanding network of qualified applicants in all regions of the U.S. Contact us for information on upcoming programs or find a factory-trained applicator in your area.

Related articles:

CIM's two-part urethane fluid-applied liners and coatings have kept liquids where they belong for over 50 years. Our technical representatives can assist you with product information to meet your coating needs; please contact us

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Topics: CIM Cold Weather Application, CIM Concrete Waterproofing, Concrete curing, Hand Applied, Spray Applied

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