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Top 8 tips to specify the right sealants and adhesives

by Madelein
Top 8 tips to specify the right sealants and adhesives

With such a vast array of sealants and adhesives on the market, it can be tough to know what to specify. FLOORS in Africa magazine spoke to Michael Berg from Den Braven and Sharon Margon from TAL to gather the top tips that you need to know to specify the right sealants and adhesives for your flooring projects:

1. Use compatible products
Tile adhesives form part of a multi-level system. The specified surface preparation, priming agents and waterproofing compounds need to be compatible with the type of tile adhesives you are using to prevent delays on site and potential installation failures.

2. Surface preparation
Surface preparation is always important. Ensure that the surface is clean and dry and where necessary, a primer has been applied to provide a suitable key for the adhesive system. This preparation may also include the application of a vapour, or moisture barrier.

Where the surface is uneven or not level, it is quicker and more cost effective to install a self-levelling underlayment prior to tiling than attempting to use tile adhesive as a levelling agent. Tile adhesives are not designed for building up of surfaces and may cause a failure in the final installation if used in this way.

3. Decide between normal, rapid- or ultra-rapid setting adhesives
The deadlines for completion of the project need to be taken into consideration, which may require that a quick- or rapid-setting adhesive be used. For projects that require fast-tracking, where repairs or refurbishments need to be completed quickly, or whilst tenants are still trading such as in a shopping centre, a rapid- or ultra-rapid setting adhesive may be required. Too early access to newly tiled floors, before the adhesive has set sufficiently, could result in an installation failure.

TAL

4. Use specialised products for specialised projects
Key factors to remember include making use of specialised products for specific requirements such as heat, chemical or acid resistance, as well as applications where hygiene is of importance, such as food production or preparation areas, or hospitals.

5. Green standards
Most projects take green building standards into consideration. Specifiers will need to make sure they have chosen a sealant or adhesive that conforms to the prescribed standards, which usually means it should have low VOC (volatile organic compound) levels.

6. Avoid low-cost products
The stresses of the economy have led to numerous substandard products on the market. Substandard products are costlier in the long run, as premature maintenance and corrections may be needed and system failures may occur. Many times, products that aren’t compatible with each other lead to consequential damages, which will lead to even costlier remedial measures.

7. Performance attributes to consider
Factors to take into consideration when specifying an adhesive are as follows:

• Movement capability
• Tear resistance
• Chemical resistance
• Substrates and adhesion
• Weatherability
• UV resistance
• Type of sealant technology (silicone, hybrid, polyurethane or acrylic)
• Shrinkage on cure
• Paintable or not
• Site assistance and training
• Warranties

8. Support and expertise is important
Technical knowhow, support, training and on-site assistance is important as this ensures that the right product is specified and correctly installed.

When is a moisture barrier needed?
A moisture or vapour barrier is a specialised surface preparation that prevents the debonding of coatings and floor toppings from high moisture vapour emission rates (MVER) in the substrate. This is not to be confused with a surface sealant, which is applied as a protective layer over a floor substrate or covering.

Manufacturers of floor coverings have stipulated moisture levels for their materials to ensure a successful end result. Ordinarily, 28-days are required for a concrete or sand/cement screed topping to cure and the construction moisture to dry out, prior to installing the floor coverings. It can happen that even though the floor surface may appear to be dry at the time of installation, when tested, moisture levels within the surface are higher than the manufacturer’s recommendations. This can be because not enough time was allowed for curing / drying out of the substrate, or the moisture levels may remain too high because of seasonal fluctuations, changes in geographic surface run-off and structural changes in and around the building.

When moisture levels in concrete subfloors have a base Relative Humidity (RH) reading greater than 75% RH, application of a suitable vapour barrier is the best course of action. Floor coverings should be applied within 12 to 16 hours after application, or as per the manufacturer’s instructions. When the product is to be overcoated with a trowel finish resin screed, broadcast an aggregate on the surface at a rate of approximately 200 to 250g/m². When the product is to be overcoated with a cementitious underlayment, immediately after application broadcast into the wet resin until it is fully blinded with aggregate.

Specialised tip: Substandard products are costlier in the long run, as premature maintenance and corrections may be needed and system failures may occur.

Full thanks and acknowledgement are given to www.denbraven.co.za and www.tal.co.za for some of the information contained in this article.

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Main image courtesy of iTe Products

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