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Benefits Of Floor Preparation – Priming

Neil Sanders on the benefits of priming

THIS month I will discuss the vital importance of priming. With so many high performance adhesives and smoothing underlayments on the market, flooring contractors can incorrectly perceive priming to now be unnecessary.
Primers can be the key to long-term success for a flooring installation. Flooring primers are designed to improve the performance of the bond created between a substrate and other material, primarily adhesives or smoothing underlayments. The absence of priming, alongside inadequate management of subfloor moisture, is one of the most common causes of failure for completed flooring installations.
The benefits of priming: In addition to improving bond performance, primers can also reduce the incidence of surface defects and imperfections, such as ‘pin holing’ in smoothing underlayments, which can become visible through resilient floorcoverings, ruining the aesthetic success of a finished flooring project and also weakening the integrity of the smoothing underlayment.
Another purpose for primers is to enhance the application characteristics of flooring installation products. By sealing the porous surface of a subfloor with a primer, the surface tension is reduced, which will improve the flow properties of any materials being subsequently applied.
Using primer also reduces the amount of water drawn into a subfloor, helping to maintain the open time of adhesives being applied directly to concrete surfaces and porous screeds.
Equally, when primer is applied prior to the application of cement-based smoothing underlayments, this helps the smoothing underlayments to retain a wet edge for longer, preventing overly rapid drying. With any type of cement based underlayment, the retention of water is vital in ensuring the mechanical properties of the product are achieved.
The selection process: When selecting the most appropriate primer for a new flooring project, it is vital to consider the condition of the substrate and the type of smoothing underlayment or adhesive that will be used.
Polymer emulsion primers, such as acrylic systems, are recommended for use with cement-based screeds. Some neoprene primers have been designed for use in a broader range of both absorbent and non-absorbent applications. Epoxy or polyurethane primers offer the greatest benefits for resin-based screeds.
Selecting an inappropriate primer, or failing to correctly use a primer according to instructions, can lead to failure of the finished floor, resulting in time-consuming and expensive remedial work.
Preparing a subfloor: Floor surfaces must be suitably prepared before installating a primer. A subfloor that is sound, smooth, dry and free from contaminants offers the best surface to receive a primer, and, in the case of concrete and sand/cement screeds, the subfloor must also be cured and any laitance removed prior to application.
Subfloors that are ‘damp’ must be treated with a moisture management system, such as a waterproof surface membrane, before the application of a primer if required. A visual inspection of the subfloor is not adequate to detect residual construction moisture or rising damp. We recommends that flooring contractors always conduct a moisture measurement test during the initial planning stages.
In addition to the benefits priming can offer when working with absorbent and non-absorbent subfloors, primer can also be used to prepare contaminated surfaces, as an alternative to mechanical removal or the application of a professional smoothing underlayment designed for use directly over adhesive residues.
However, whilst stable adhesive residues may be suitable for priming, surfaces that contain silicone-based treatments may inhibit bond formation. Contractors should always consult manufacturer guidelines before selecting the most appropriate primer system to use with a contaminated subfloor.
Primers should be standard during subfloor preparation by today’s flooring contactors. Quick to apply and easy to manage, primer systems offer short and long term benefits for contractors to guarantee a high quality, lasting floor finish.

Neil Sanders is technical director for F Ball and Co
T: 01538 361633 www.f-ball.co.uk

This article has been reproduced from the Contract Flooring Journal. You can find them at www.theflooringgroup.co.uk.