Floor Preparation

Any preparation work carried out on sub-floors is intended to provide a surface that is clean, dimensionally stable, rigid and sufficiently flat so that the new floor covering can be well adhered and provide a hardwearing and durable floor finish.

General requirements are:

The actual requirements for any particular floor can usually only be assessed after an on-site inspection and moisture-level check.

Some of these requirements may not be within the control of the flooring contractor, especially the requirement for dimensional stability of concrete and timber floors.

Rigidity of the sub-floor can be improved by stiffening the construction of the sub-floor and steps can be taken to achieve the required flatness and cleanliness.

Many problems arise from a high moisture content in the floor. In the case of new concrete or screeded sub-floors, the required drying out times may not have elapsed when the new flooring is expected to commence installation.

At site temperatures of 20C and a relative humidity of 65% a new concrete slab requires at least 6 weeks drying after curing, and a new screed requires at least 3 weeks drying after curing. These times should be extended under poor drying conditions, e.g. cooler and poorly ventilated conditions.

Existing concrete floors that show a high moisture level can usually be treated with a waterproofing compound. These products work by slowing down the rate of moisture transfer from the floor to the atmosphere to a rate that the flooring overlay can accommodate.

Timber and concrete floors that previously had other types of floorings adhered to them can sometimes present problems since the old adhesive residues may be very well adhered and difficult to remove. If at all possible, the best procedure is to remove all surface residues and expose a clean surface. If this is not possible, then in many cases a lining board or a cement leveling compound can be installed over the residues to provide a clean flat flooring surface.

Many confuse the term level with flat when it comes to sub floors. With most floor installations (unless setting up a bowling alley!) we want to achieve FLAT subfloors. Floor preparation is just as important as installing the floor itself. Realistically, it should be considered the most important. Unfortunately many installers don't place the emphasis as they should. Neglecting floor preparation will often result in failure. It may not be apparent immediately, but over time, the flooring will loosen from the subfloor, begin to make strange sounds, and eventually fail.