Setting+out+stairs

When measuring up for stairs, it is important to know the exact measurements of the length and height of the flight, to allow for accurate calculation of the treads and rises. The following proportions must be obtained: This is the vertical distance measured between landings or between finished floor levels. This is the horizontal distance measured between the face of the first riser and the face of the last riser. This is the vertical distance measured from the top of one tread to the top of the next tread. This is the horizontal distance measured between the face of one riser and the face of the next riser. (The nosing is not included in this measurement)
 * PROPORTIONS OF STAIRS**
 * Rise of Flight:**
 * Going of Flight:**
 * Rise of Step:**
 * Going of Step:**
 * Note:** The rise and going proportions must remain the same throughout the flight(s) of stairs.

The **Buidling Code of Australia** (BCA) outlines the requirements for building stairs. Go to the regulations page to find the out the minimum and maximum and other restrictions related to stairs. Stair regulations

It is critcal to remember that there will always be **ONE MORE** rise than going flight; measurement, i.e. ( 550 + 700) ÷ 2 = 625mm, substitute the average rise measurement for ‘R’ in the formula, then transpose the formula to find ‘G’.
 * Doing the calculations:**
 * CALCULATING RISE AND GOING FOR A FLIGHT**
 * Method 1 –** for ‘unrestricted’ going:
 * Step 1** Obtain the rise of the flight;
 * Step 2** Assume a suitable rise, when the average rise is (190 + 115) ÷ 2 = 153mm ;
 * Step 3** Establish the number of risers by dividing the assumed rise into the rise of the
 * Step 4** Establish the length of the going by using the average slope relationship

Using ‘Method 1’, calculate the number and size of the rises and goings for a flight of stairs with a rise of flight of 2.650m and an unrestricted going of flight. There must be full equal-sized risers, therefore round off to 17 risers. The height of each riser 2650 ÷ 17 = 155.882, say 156mm The size of the goings will be based on the **average slope relationship** measurement (550 + 700) ÷ 2 = **625mm.** Now substitute the known measurements for the formula symbols: (2R+G) = 625 (312 + G) 625 Now transpose the formula to find the value of ‘G’: ’G’ = 625 - 312 = 313mm complies with the **BCA** flight; flight going. Check to see if both the rise and going measurements comply, by substituting them for ‘R’ and ‘G’, and apply the formula (2R + G).
 * Example 1:**
 * Step 1** Rise of flight = 2650mm
 * Step 2** Assume a rise, say average (190 + 115) ÷ 2 = 153mm
 * Step 3** Number of risers 2650 ÷ 153 = 17. 320 risers
 * Step 4** The number of goings will be one (1) less than the risers, therefore 16 goings.
 * Method 2** for a ‘restricted’ going:
 * Step 1** Obtain the rise of the flight;
 * Step 2** Assume a suitable rise, when the average rise is (190 + 115) ÷ 2 = 153mm ;
 * Step 3** Establish the number of risers by dividing the assumed rise into the rise of the
 * Step 4** Establish the length of the going by dividing the assumed rise into the restricted

Using ‘Method 2’, calculate the number and size of the rises and goings for a flight of stairs with a rise of flight of 1.900m and a restricted going of flight of 3.350m. There must be full equal-sized risers, therefore round off to 12 risers. The height of each riser 1900 ÷ 12 = 158.333, say 158mm
 * Example 2:**
 * Step 1** Rise of flight = 1900mm
 * Step 2** Assume a rise, say average (190 + 115) ÷ 2 = 153mm
 * Step 3** Number of risers 1900 ÷ 153 = 12.418 risers
 * Step 4** The number of goings will be one (1) less than the risers, **therefore 11 goings**.

The size of the goings will be based on the length of the flight going divided by the number of goings: 3350 ÷ 11 = 304.5, say 305mm Therefore, there will be **12 risers** at 158mm and 11 goings at 305mm. Check formula for compliance with BCA (2R + G) = ( between 550 and 700mm) 316 + 305 = 621mm, **therefore it complies.**

The following Powerpoint offers some solutions to setting out stairs where there are restrictions; There are many more solutions so discuss these with your trainer.

To calculate the lenght of string material required use **Pythagoras theory.**
 * Calculating the length of strings:**



Allowances need to be made for:
 * Mortise and tenon joints.
 * The size of the newel post
 * Joining into skirtings
 * Hooking over floor joists at landings

Watch the power point presentation for more details • **

Setting out stringers:**
 * Using a steel square and buttons or adjustable guide:

**
 * 1) The //rise// (vertical measurement), and the //run// (horizontal measurement). Note that the stringer will rest partially on the horizontal surface.
 * 2) For a cut string a framing square is placed on the stringer so that the desired rise and tread marks meet the edge of the board. The outline of the square is traced. The square is slid up the stringer until the tread is placed on the mark and the process is repeated. If it is for a closed string, a margin line is needed. the margin line sets the distance awya from the top edge if the string for treaqd and rise intersections (see Fig 26 above)

You can also use an adjustable template, which has the tread, riser thickness and wedge allowance prepared ready to be traced onto the string to suit the particular set out required. The adjustable guides are set to suit the string width being used, which allows the template to slide along after each set out is made. The detail below provides set out details to allow for the fabrication of a standard template but if. The quickest way to remove the waste from string set outs and cut neatly to the outline is to use a router fitted with a template guide. //**Don’t forget**// to increase the size of the string template to allow for the router template guide. This allows the router cutter to cut neatly along the set out lines and remove the waste at the same time.
 * Templates**
 * Templates as router guides**

You may want to go to the library and borrow the DVD listed below: CTD23/1 STAIRS - TYPES/DESIGN/MEASUREMENT