1. Knowledge of quantities / calculating areas

2. Knowledge of technical information, quantities and communicating with others

3. Materials calculations
Area - calculations
Rectangle
Area is used in construction for costing work and estimating quantities. It is normally measured in squared metres.
A square metre is the surface of a square measuring 1 metre by 1 metre, and is written as 1m2.
It is calculated by multiplying the two sides together.
It is the space that counts the area, not the shape. 2m
0.5m 1m 4m
0.25m

4. Materials calculations
Area - calculations
Squares
All areas of squares and rectangles are worked out in the same way.
You simply multiply the length by the height
5m x 2m =
10m2
3.5m x 2m =
7m2
3m x 4m =
12m2
2.5m x 4m =
10m2

5. Materials calculations
Take out area 4m 3m
Step 1:
Work out the total area:
4m x 3m = 12 m2
Step 2:
Work out the area of the opening(s):
2m x 1m = 2m2
Step 3:
Take the openings from the total area:
12m2 – 2m2 = 10m2
The area of the wall is 10m2
12m2
2m2
2m2
10m2

6. Materials calculations
Formula - rectangles L
Area
= Length (L) x Height (H)
= mm2 or m2 H
2m2

7. Materials calculations
Area - calculations
Triangles
The area of the triangle is always half the area of a square with the same base and height
Area of a triangle =
Base x height 2
HEIGHT
2m2
BASE

8. Materials calculations
Formula - triangles
Area
= ½ Base (B) x Height (H)
= mm2 or m2 H
2m2 B

9. Materials calculations
Area if a gable end 4m 3m
6m2
Step 1:
Divide up the wall
Step 2:
Work out the area of each section:
3m x 4m = 12m2
4m x 3m / 2 = 6m2
Step 3:
Add the two areas together:
12m2 + 6m2 = 18m2
The area of this gable is 18m2 4m 3m
12m2 4m 3m
18m2

10. Materials calculations
Area - calculations
Circles
The area of a circle is calculated using  (pi) = 3.14
The formula to find the area of any circle:
Area =  x radius x radius
The radius (r) is the length from the centre to the edge
The diameter (d) is the length from edge to edge, through the centre r d

11. Materials calculations
Formulae - circles
Circle Half circle Quarter circle 4m 3m 2m
2m2
The area of this circle is
=  x rad x rad
= 3.14 x 4 x 4
= m2
The area of this half circle is
= ( x rad x rad) / 2
= (3.14 x 3 x 3) / 2
= m2
The area of this quarter circle is
= ( x rad x rad) / 4
= (3.14 x 2 x 2) / 4
= 3.14 m2

12. Materials calculations
Exercise 6m
2.5m
3.2m 4m
Area = m2
50.24
Area = m2
113.04
Area = m2
19.625
Area = m2
16m 3m
7.4m
14m
Area = m2
Area = m2
153.86
Area = m2
100.48
Area = m2
7.065

13. Materials calculations
Formula - circles
Radius (r)
Length from centre to outside edge (mm or m)
Diameter (d)
Length from edge to edge through centre (mm or m)
Circumference (c)
Perimeter or edge of circle = 2 r
Area
 x r x r = r2 (mm2 or m2) c r d
2m2

14. THANK YOU