Floor Finish

The majority of houses built before the 1930s had square-edged floorboards. They could be of various sizes but are generally 150–175mm wide and 18–25mm (finished thickness). The boards were fixed with special nails called brads, which helped to prevent them from working loose with  age, and the boards were usually laid with staggered joints as shown in the diagram below. Obviously these joints must occur over joists. From the 1930s onwards wider use of more sophisticated woodworking machinery facilitated the production of tongued and grooved boards, which have distinct advantages over their square-edged counterparts:

- point loads from heavy furniture are spread across other boards, thereby allowing reduced board size
- there is less chance of the boards warping and the close-fitting joints form a reasonably smooth surface on which to lay a variety of finishes (one disadvantage is that the boards are difficult to lift for access to the services)
- they provide better smoke and fire resistance.

Both types of board are made from fast-growing coniferous trees (known as softwoods), although solid hardwoods, such as oak, may be found in more prestigious developments.

In modern construction, both tongued and grooved floorboards and square-edged boards have largely been superseded by chipboard, which consists of small wood chips bonded with synthetic resin and then compressed to form large sheets. The boards are typically 2,400 x 600 x 18mm thick and are available with tongued and grooved edges all round. A sheet of chipboard is four to five times the width of a typical solid timber floorboard. They have good wear resistance and should be maintenance free as long as they do not remain wet for long periods. Their popularity lies in their cost advantage over solid timber. To ensure that the requirements of the Building Regulations are met, floor boarding that will not be damaged by spilt water or moisture in rooms such as kitchens, utility rooms, bathrooms and WCs should be used. This could be either a proprietary moisture-resistant type or a minimum of 20mm thick natural timber floor boarding. Even these materials cannot withstand long-term water saturation.

Laminated flooring has become popular in recent years. Products range from thick veneers of expensive timbers (‘engineered timber’), laminated onto moisture-resistant man-made board, to plastic-based timber-lookalike materials. All laminate floors are tongued and grooved on all edges and they are generally designed to provide a floating floor (see below) on top of a solid concrete floor, although some are designed to be fixed directly to timber joists and some to be applied to a chipboard floor.