Instruction Example 3.1.: Working of Boards for a Roof Base Facing

The face and bottom boards for a couple roof base facing are to be worked.

Material

Boards with tongue and groove planed on one side, board lengths between 3000 mm and 4100 mm

Figure

Hand tools and machines

Smoothing plane, circular saw bench

Measuring and testing means

Folding rule, measuring tape (if necessary)

Auxiliary accessories

Pencil, work bench (working table)

Necessary previous knowledge

Reading of drawings, measuring and testing, planing, operation of the circular sawing machine, fundamental arithmetic operations

Sequence of operations	Comments
1. Determine the board length. - 4100 mm long boards cover 5 bays 5 · 803 mm = 4015 mm	Use attic framing drawing!
- 20 bays would be 4 board lengths 4 · 4015 mm = 16060 mm.	Roof base facing must cover the total length of the building. Length of building = 16990 mm. 4 board lengths are not feasible!
- Initial board 365 mm = 2874 mm Length selected: 3000 mm	Use attic framing drawing! Initial board over 3 bays. Beam distance from centre to centre!
- Intermediate board 5 · 803 mm = 4015 mm Length selected: 4100 mm	over 5 bays, three joints = 15 bays
- 20 mm + 365 mm = 2071 mm Length selected: 3000 mm	over 2 bays, since 3 + 15 + 2 = 20 bays The difference of 929 mm is required for closing the roof base facing.
2. Determine the board width. - Lay out eaves flashing in scale 1:1, determine and measure the width: face boards: 120 mm width bottom boards: 130 mm width	Consider maximum board width. See drawing of Instruction Example 3.2. Add about 10 mm for tongue and groove to be cut off.
3. Determine the number of boards. - Face boards: 120 mm wide 2 · 2 = 4 boards 3000 mm long 3 · 2 = 6 boards 4100 mm long	Use laid-out eaves flashing and determination of step 1 above.
- Bottom boards: 130 mm wide 2 · 2 = 4 boards 3000 mm long 3 · 2 = 6 boards 4100 mm long	Roof base facing is to be provided at both sides of the couple roof.
- List of boards: 8 boards of 3.0 m length and 12 cm width 12 boards of 4.1 m length and 12 cm width 8 boards of 3.0 m length and 13 cm width 12 boards of 4.1 m length and 13 cm width.
4. Select boards of adequate length and width in timber yard.	Consider surface quality, too!
5. Store boards according to width at the side of the circular saw bench.	Make sure that there is enough freedom to move!
6. Saw boards to width. Board (1) 120 mm Board (2) 120 mm + tongue length Board (3) 111 mm + tongue length Board (4) 110 mm	Use laid-out eaves flashing. (See drawing of Instruction Example 3.2.). Think of tongue length. Use stop at circular saw bench! 1 mm on board 3 is needed for smoothing of the surface. (See drawing of Instruction Example 3.2.)
7. Chamfer boards - Chamfer boards (1) and (4) at the groove side. - Chamfer board (2) at the tongue side. - Chamfer board (3) at three sides and smooth visible projection.	Put board flat on work bench. Maximum chamfer 3 mm. Planed side to be on top. Clamp board edgewise on work bench and plane off to 110 mm. Lay board flat and chamfer at tongue and groove sides. Turn board over (rough side on top) and smooth visible areas.
8. Store boards for transportation.	Protect stored boards against possible damage during storage!

Attic Framing