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The Difference Between Self-Levelling Toppings And Underlayments And The Importance Of Using The Right Primer

What is the difference between a self-levelling topping and a self-levelling underlayment? And how do you select the right primer?

August 12, 2020. 3:47 AM

Concrete toppings are formulated to function as abrasion-resistant wearing surfaces with high-compressive strengths to handle residential to commercial applications e.g. mall stores, restaurants, hotels, residential units...including industrial warehouse floors subject to continual vehicular traffic. Decorative toppings can be stained, carved and polished, making them a great alternative to traditional flooring. Examples of toppings are products in the ULTRATOP Range.

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Underlayments are formulated for levelling and smoothing of uneven substrates, providing a flat surface for installation of tile, stone, wood, resilient and other floor coverings, and must be covered. Most underlayments are meant for interior use only. Products such as NOVOPLAN 21 and those in the ULTRAPLAN range are commonly selected for these applications.

Since both toppings and underlayments are highly engineered self-levellers designed for specific applications, always consult the most current technical data sheet for proper use and limitations.

What about the primer, does it really matter which one I use? In a word, yes, for both toppings and underlayments, primers improve adhesion, and reduce surface defects such as pinholes in the finished surface. When selecting a primer the following factors must be considered:

a) Type of substrate - porous or non-porous, concrete, gypsum-based, plywood, existing tile, adhesive residue.
b) The service conditions that the topping or underlayment will be exposed to during its service life, ranging from warehouse to residential flooring.

Primers can range in chemical make-up from water-based synthetic polymers (e.g. PRIMER G) to two-component, 100 % solids, epoxy resins (e.g. PRIMER SN) and are formulated for various substrates and porosities to match the specific application.

Users are advised to read the relevant technical data sheet for the topping or underlayment and follow the recommendations for substrate priming.