1. CALCULATING THE LENGTH OF THE STRING
Use Pythagoras theory to calculate
the length of c = a2 + b2

2. CALCULATING THE LENGTH OF THE STRING
a = 4 x rise
Say 4 x 150**
= 600mm
Using Pythagoras theory c = a2 + b2
We calculate the approximate length of the string
e.g.: C =

3. CALCULATING THE LENGTH OF THE STRING
b = 3 x going
Say 3 x 310mm**
= 930mm = 0.93m
a = 4 x rise
Say 4 x 150mm**
= 600mm = 0.6m
Using Pythagoras theory c = a2 + b2
We calculate the approximate length of the string
e.g.: C =
0.932 = 1.225m

4. CALCULATING THE LENGTH OF THE STRING
Length of timber needed for String = 1.225m or take it to the nearest stock length 1.3m or 1.5m (depending on the species or timber seller)
Using Pythagoras theory c = a2 + b2
We calculate the approximate length of the string
e.g.: C = = 1.225m

5. 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