Exploring Choice With Timber Flooring

Timber flooring is traditionally one of the oldest forms of flooring which has seen an increase in popularity in recent years. Many different species of timber are available which are selected mainly for their appearance and durability. Hardwood flooring is available in many forms.

Solid strip or plank flooring

Solid strip or plank floors are mainly manufactured in tongue and groove (T&G) and end-matched pre-finished boards but may be supplied as unfinished strips, fixed individually. They are usually structural grade boards which will span between supports. Pre-finished boards tend to offer a faster installation time and a high level of consistency of the surface finish. Boards are manufactured in a variety of sizes and may be installed by mechanical ‘secret fixing’ through the tongue to a timber subfloor or softwood joists or battens. They may also be glued down to a solid subfloor using a proprietary adhesive or laid as a floating floor on an underlay and moisture barrier when using a proprietary manufacturer’s system in accordance with the manufacturer’s recommendations.

For sports, dance or other activity floors, the boards will usually be nailed to a ‘semi-sprung’ batten system fitted with rubber or neoprene pads or a continuous layer of polyurethane foam on the underside. Some of these systems are height-adjustable to allow them to be laid on uneven concrete or where the subfloor level changes. Sports or dance floors will usually need to comply with EN14904 class A3 or A4 to ensure the correct performance characteristics in terms of shock absorption, friction, etc.

Engineered boards

Engineered boards are available as a multi-layer board in various timbers and thicknesses. Boards are normally pre-finished at the manufacturing stage, comprising a top layer of decorative hardwood 3mm to 6mm thick with a softwood ply or block-board substrate. They are usually T&G jointed and end matched.

Various board thicknesses are available to suit overlay or structural installations. Where fixed to battens or joists, boards will normally be ‘secret nailed’ through the top of the tongue; where laid as an overlay they may be fully edge-glued or boards joined together with a special locking profile T&G joint; where installed as a floating overlay floor a proprietary underlay is necessary. For cementitious bases, a surface moisture barrier is usually required.

Thinner boards are predominantly used for residential installations and thicker, structural boards for sports and commercial buildings.

Solid wood blocks

Solid wood block flooring may be laid over any sound, dry, level subfloor and is usually glued to the subfloor using bitumen or polymer adhesives.

Wood blocks are normally supplied untreated and sanded/finished on site. These blocks are manufactured in various sizes with a T&G on either side and grooved at either end. They are usually installed by adhering to a flat, dry screed base finished with a suitable smoothing and levelling compound. They will often be manufactured in left hand and right-handed versions to allow them to interlock properly when laid in herringbone and similar patterns.

The most popular pattern is herringbone, but double herringbone, basket weave, ladder and brick patterns can be achieved. A two-block border may be used at the perimeter.

NOTE: It is desirable that block floors are set out so as to achieve a symmetrical layout but dimensional variations may dictate that an alternative be considered. The first two lines of blocks should be laid on either side of an approximate centre line and should then continue outwards until a space is left for a border of longitudinally placed blocks plus an expansion gap.

Solid overlay floors, strip and plank

Solid overlay strip or plank floors come in various sizes, typically 12mm or 14mm thickness and are often supplied factory finished. These floors require a sound, flat and dry subfloor to support them and will generally not span between joists or battens. May be laid as floating overlay floors using the manufacturer’s proprietary system or glued down. On timber subfloors, they may be ‘secret nailed’ through the top of the tongue. For cementitious bases, a surface moisture barrier is usually required.

Solid timber floors expand mainly across the width and it is advantageous to lay boards and strips so that the number of board or strip widths is kept to a minimum. It is usual to lay the boards or strips parallel to the longest wall and to leave perimeter expansion gaps.

The position of doors and windows and the direction of existing floorboards or joists should also be considered when deciding which direction to lay the boards.

NOTE: Boards and strips should be laid in as random pattern as possible. Header joints and stave ends must not fall in line and be at least two strip widths apart in adjacent runs. Overlay strips should be set out in the same manner as boards and strips. Pre-finished boards on battens or joists will usually be laid so the header joints are supported by battens.

Wood mosaic panels

Wood mosaic panels are manufactured from a variety of timbers such as walnut, oak and some tropical timbers which are chosen for their hardness and stability. Good resistance to wear and attractive appearance are just two features of mosaic panels. They are also among the cheapest type of hardwood flooring.

Mosaic panels are used in many applications including housing, schools, churches, recreational and sports areas. They are available in feltbacked, mesh-backed, paper-backed, paper-faced and are usually pre-sanded for easy installation.

The panels are supplied in various sizes, generally 480mm × 480mm and 477mm × 477mm, 8mm or 10mm thick. Sixteen opposing squares, each comprising five or six fingers per square, are set in a basket weave pattern. Mosaic flooring can be laid over any sound, dry, level subfloor and are usually glued to the subfloor using bitumen or polymer adhesives and are then sanded and finished.

It is desirable that the floor be set out to achieve a symmetrical layout, but dimensional variations may dictate an alternative be considered.

The first two lines of panels should be laid on either side of an approximate centre line, then continued outwards until a gap for expansion is left.

Parquet battens

These are manufactured mostly from oak, with finished sizes typically 380 × 60 × 10mm, or 280 × 70 × 10mm. Other sizes and timbers are available in order to produce a wider choice of patterns. Battens are supplied unfinished with plain non-jointed edges. They are generally installed onto a dry and level base covered with a minimum thickness of 4-6mm resin bonded plywood firmly fixed to the existing subfloor. They are usually glued with a PVA adhesive and pinned through the face using 25mm panel pins. The pins are punched home, filled, sanded and polished. At the perimeter, a two-line border of oak or a darker timber is formed.

For more technical information about timber flooring visit the CFA Guide to Contract Flooring.