Flooring System
There are four common floor systems, tongued and grooved, overlay, parquet, and structural plywood (veneer faced) flooring.

Tongue & Groove (T&G) Flooring
Tongue and groove flooring utilises lengths of solid timber boards. The boards are generally 19mm thick and range in width from 60 to 150mm. T&G boards are generally laid over a timber sub-floor (joists), but can also be laid over concrete slabs (directly, or on timber battens, or on plywood) or over timber sheet or strip flooring.

Each board has a protruding ‘tongue’ along one edge and a machined groove along the other so that each board fits into the adjoining board. The ends of boards can also be machined with a tongue and groove profile termed ‘end matched’. End matched boards allow the end joint to occur randomly rather than over joists or battens thus improving installation efficiency, saving most docking of boards and resultant wastage of material on site as required with butt joints.

T&G board profiles include face-nail and secret-nail designs. Face (or top) nailing describes driving nails through the top face of the board into the substructure. Where the floor is to be sanded and polished, the nails are punched below the board surface and the resulting hole is filled with a suitably coloured filler. Secret nailing describes fastening though the tongue of the board into the substrate. Each subsequent board then effectively conceals the nailed tongue of the proceeding board. The face of the board is left unblemished. Secret nailed board width is limited to 85mm as only one nail is used to secure the board at each joist. (Refer to Figure 2). For wider boards a combination of nailing and adhesive may be acceptable.
 

Figure 2: Typical tongue and groove profiles

 

Overlay & Floating Timber Floor Systems
Overlay and floating timber floor systems are non-structural, meaning they rely completely on the substrate over which they are installed for support. Some products are backed with or installed over a resilient layer, providing a degree of cushioning and sound insulation. Others may be fixed or adhered directly to the substrate. The term ‘floating’ floor relates to those products which are not fixed directly to the substrate.

Generally these products can be divided into plywood based, MDF cored and solid timber systems. The plywood version has a face veneer with the remainder of the product made up of (typically) softwood veneers. Some may also have a layer of hardwood as the bottom layer of the plywood configuration. This gives it balance and results in a more stable product. Milled solid timber is also available as an overlay system. The lengths of the individual boards are typically shorter than those found in conventional floor boards. Some are supplied pre-finished whilst others require sanding and finishing on site.

Adhesive fixed T&G flooring is available in thicknesses ranging from 12 to 19mm. These boards are attached directly to the substrate surface with adhesive. The tongue and groove is generally set towards the lower portion of the board, particularly in the thinner variations. This allows additional timber thickness above the tongued and groove joint to cater for sanding for both initial and maintenance sanding where required. Some products are pre-finished, others are sanded and coated on-site.
 

Figure 4: Floating timber plywood floor

Figure 3: Adhesive fixed tongue and groove flooring

 

Figure 5: Feature veneer plywood overlay flooring

 

Figure 6: Popular parquet patterns

Parquet
Parquet is a system of timber flooring that comprises small blocks of timber, laid in one or more of a variety of pattens from simple block to highly intricate basket weave. (Refer to Figure 3).The range of patterns available is almost limitless and may be further enhanced by mixing various species or introducing contrasting borders. Inlays of other materials such as granite, ceramic tiles, etc., can also be incorporated.
 

Structural Plywood Flooring
(Decorative Veneer Faced)
Structural plywood flooring comprises a plywood base with a decorative hardwood face veneer. It has the capacity to be installed as a structural floor spanning between joists or battens, or fully supported on a continuous substrate (e.g., concrete slab), in the same manner as an overlay floor. There are both sheet and plank type products, joined either with a plastic tongue which fits into a groove in the edge of the material, or a more conventional milled tongue and groove joint. For span capacity and the specific fixing requirements, refer to the producer’s instructions.

The face veneer thickness varies between producers. The thicker this top face veneer is, the better the ability to be re-sanded and finished. Unlike conventional strip flooring no ‘level’ sanding is required in the initial finishing process.