 |  | Carpentry for Vocational Schools - A Teacher's handbook (GTZ, 252 p.) | ||
 |  | 16. FLOORING | ||
|  | (introduction...) | ||
| | 16.1. Different types of flooring boards | ||
| | 16.2. Laying of flooring boards | ||
| | 16.3. Finishing of flooring | ||
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TOPIC: 16. FLOORING
INTRODUCTION: This topic teaches students different types of flooring boards, how they are laid and how to finish the floor.
OBJECTIVES:
16.1. Students should be able to identify the different types of flooring and their characteristics.
16.2. Students should be able to describe the procedure and lay floor boards.
16.3. Students should be able to carry out the procedure of finishing a floor.
METHOD:
16.1. Prepare samples of different floor boards and display them in the classroom. Students take notes from the black board.
16.2., 16.3. These two chapters are difficult to demonstrate if there are no building projects going on.
Prepare photocopies of the drawings from this topic which are glued into students trade theory book after the topic has been taught in the classroom.
NOTE: At the end of this section prepare a worksheet for students to complete as homework. They are to be corrected and assessed later.
The floor in a timber house may be laid and fixed as soon as the walls and the roof are covered.
a) Plywood: - Plywood is made from thin pieces of timber called veneer, which are glued and pressed together. Plywood always has an odd or uneven number of veneers. The outside veneers are called face veneers, and they are of good quality, with no splits, cracks or defects in them.
Figure
b) Laying plywood as flooring: - Plywood is a fast way of laying flooring. The thickness of the plywood should be 20 mm. The, joints in the sheet must be made on a joist. Plywood sheets are nailed to the joists and the nail are punched immediately. Where special size are required, cut and fit them in.
Figure
c) Chipboard: - This board is made from fine chips of timber which are glued together by heat and pressure. The smaller chips are used on the outside faces to give a smooth finish and the bigger chips are used in the middle to lower the cost. Using chipboard as flooring, the thickness of the boards should be at least 20 mm, because the chipboard is quite porous. It cannot stand heavy loads and can easily break. In laying the boards as flooring boards the procedure is the same as for plywood flooring.
Figure
d) Flooring boards: - Flooring boards are sold by the linear metre. Flooring timber has a tongue and groove joint and is 22 mm in thickness.
Figure
In laying flooring boards a pair of floor cramps or a chisel is used to ensure tight fitting joints. The flooring boards are cut to the required length with any joints cut centrally over the joist. The first board is nailed down against a wall with the groove-side outward. Upon the fixing of this board depends the straightness of all the others. If there is a big room, tie a rope in the middle of the room, lay a board which follows exactly the straightness of the rope and continue to lay the boards. Each flooring board is double nailed at each joist.
a) Using floor cramps: - Few boards are laid together, place a piece of hardwood (called a dogging piece) between the cramps and the boards to protect their edges and nail the boards immediately.
Figure
b) Using a chisel:- If floor cramps are not available, then one board at a time can be fixed by placing a block against the edge of the board and driving a strong chisel into each joist at the side of the block and lever with the chisel while the nails are being driven in.
Figure
c) Laying the last board: - When laying the last board on a cut in floor, leave 12 mm gap between the board and the wall plate. Tighten the last board using a chisel. Tack the nails in position first and then hammer the chisel into the joist and lever the last board in place. While maintaining the pressure, drive the nails home.
Figure
If the flooring boards are nailed, the nails are punched with a nail punch. The nail holes and other holes in the surface of the floor are filled with putty, using a putty knife. Let the putty dry and the floor can be sanded. This work can be done with a floor-sanding machine, belt sander or sanding by hand. When the floor is sanded, varnish is brushed onto the floor. Best results are obtained by High Gloss varnish. Varnish does not dry quickly, and should be left for a full day before sanding and the application of a second coat.
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