Loosely defined, a subfloor is usually the base, upon which a floorcovering is placed in a building. Usually a subfloor requires some preparation before it can receive the final floorcovering.

Contractors looking to avoid damaged, defective, deteriorated or unlevelled subfloors, need to keep a number of things in mind. Tal advises contractors to be mindful of the following when installing an underlayment to a subfloor:

1. Curing times of substrates
Allow all new concrete work and screeds to cure for at least 6 weeks and 4 weeks respectively. The substrate must attain a moisture content of 5% (75% RH) or less before applying the underlayment.

2. Even floor levels
Since these installations are normally 3-5mm thick, it is important to ensure all highs and lows in the subfloor are identified and addressed before applying an underlayment.

3. Proper surface Preparation
Ensure that the substrate is clean, dry and free of all surface contamination such as shutter release and curing agents, laitance, surface contaminants, dust, debris, etc. Contamination on the surface can impair the bond between the underlayment and substrate. Certain substrates will require priming to ensure a good bond.

Avoid costly mistakes with these tips
The success of an installation is highly dependent on the underlying conditions and the quality of the background preparations before applying an underlayment. Some key tips for success include:

• Where prevailing moisture levels do not attain 5% (75% RH) or less, apply a barrier coat that prevents the passage of water vapour and moisture through the concrete slabs.
• A priming system may be required depending on the type of subfloor you are working on, i.e. rough and porous or smooth and dense surfaces.
• All construction joints in the substrate must be extended through to the surface of the TAL Screedmaster installation in the form of voided joints to allow movement in the installation.
• The water: powder mix ratio must be strictly adhered to when mixing the underlayment.
• Use an experienced installer.

For more information, contact Tal on Tel: +27 (11) 206 9700 or via www.tal.co.za.