Stairmaking - Course: Timberwork techniques. Instruction examples for practical vocational training (Institut für Berufliche Entwicklung, 34 p.): Instruction Example 8.2.: Determination for the Ratio of Rise and Tread

Stairmaking - Course: Timberwork techniques. Instruction examples for practical vocational training (Institut für Berufliche Entwicklung, 34 p.)

		(introduction...)
		Preliminary Remarks
		Instruction Example 8.1.: Taking off Dimensions at the Stairwell
		Instruction Example 8.2.: Determination for the Ratio of Rise and Tread
		Instruction Example 8.3.: Scribing of landing connections
		Instruction Example 8.4.: Manufacture of Template and Angular Board
		Instruction Example 8.5.: Scribing and Preparing the Stair Strings
		Instruction Example 8.6.: Manufacture of Steps and Risers
		Instruction Example 8.7.: Assembly of the Stair Flight

The dimensions given below have been taken off the stairwell and entered into the hand-sketch.

Details of the stairs to be built in:

- straight stairs with two branches of flights, mortised
- string thickness: 50 mm
- riser thickness: 15 mm
- floor thickness main landing: 24 mm

, ns = 8

Auxiliary accessories

Paper, pencil, slide rule or calculator/computer

Necessary previous knowledge

Fundamental arithmetics: adding, subtracting, dividing, multiplying

Explanations to the working drawing

(1) main top landing

(2) main bottom landing

(3) half-landing

(4) upper edge of bare ceiling

Sequence of operations	Comments
1. Sequence stair height for one branch of flights.	Divide the measured floor-to-floor height by two.

2. Determine the height of rise.
s=171 m
3. Check the flight length.	Start from the size n_a · a = L and compare with the size at the stairwell (2090 mm).
L = n_a · a L = 7 · 290 mm L = 2030 mm	The difference of 60 mm is to be compensated at the top landing connection!
4. Check the half-landing height. Gh + d₁ - d₂ ⁼ Lh! 1410 mm + 24 mm - 40 mm = 1394 mm ¹ 1368 mm	Check from the main top landing. Lh = 1368 mm! Half-landing is to be raised!
5. Find out the difference. 1394 mm - 1368 mm = 26 mm	Half-landing is to be raised by 26 mm. Half-landing is not removed but 26 mm thick boards are put on before the floor is constructed!

Determination of the Ratio of Rise and Tread