Composite Rate Build Up – External Walls Superstructure
The Elemental Estimate layout and grouping of items will be used in this example. When building up composite rates for Approximate Quantities, you have to follow some basic principles. We are going to illustrate a composite rate buildup for External Walls:
Superstructure 230mm external one brickwall 2900mm high, 150mm wide reinforcement every third course, including one coat cement plaster on smooth plastered walls both sides, one coat plaster primer and two coats Plascon Wall paint on both sides.
Step 1
First, you have to determine the Group unit of measurement. When you are measuring the external envelope (superstructure external walls) in Elemental or Approximate Quantities estimating, the group unit of measurement is the square metre (m2).
Step 2
The second step is listing all associated Bill items that can be mapped to External Walls by area. These are:
 230mm one brickwall – (m2) Rate – R235
 150mm wide brick reinforcement – (m) Rate – R2.50
 One coat cement plaster – (m2) Rate – R30
 Painting (undercoat and overcoat) – (m2) Rate – R30
Step 3
Since your Group unit is the square metre (m2), you should convert the Bill item rates to Cost per Square Metre.
Rate Build Up GROUP – EXTERNAL ENVELOPE (SUPERSTRUCTURE) 
Rate – Cost Per Square Metre (m2) Rands  
Approximate:  Elemental:  
1m2 of One brickwalls:  
1m2 = R235  235  235 
1m2 of Brick reinforcement:  
1 course = 86mm including mortar joint
3 courses = 86 x 3 = 258mm 

1000mm Wall height has :
1000/258 = 3.88 Layers ,which is approximately 3.00 Layers. Therefore 1m2 of brickwall has 3 Layers of brickforce. 3 Layers x 1m = 3m of reinforcement. 

3m x R2.50 = R7.50  7.50  7.50 
242.50  
1m2 Cement plaster:  
1000 x 1000 x 2 sides  
1 x 1 x 2 = 2.00m2  
2.00m2 x R30 = R60  60  30 
1m2 Painting on plaster:  
1000 x 1000 x 2 sides  
1 x 1 x 2 = 2.00m2  
2.00m2 x R30 = R60  60  30 
60  
Composite Rate – SUPERSTRUCTURE EXTERNAL ENVELOPE  362.50 
The composite rate for EXTERNAL ENVELOPE (External Superstructure One Brickwalls) is R362.50 per square metre.
Elemental Layout and Grouping
Items which go into the element EXTERNAL ENVELOPE and components Brick & Block Walls and External Finishes are stated in the description:

Unit  Quantity  Unit Rate  Cost/m2  Subtotal  Cost  
EXTERNAL ENVELOPE


Brick and Block Walls:


230mm One brickwall in superstructure (No openings), including 150mm reinforcement, beam filling, gable walls, ties to concrete and sundries.  M2  242.50  
External Finishes:  
One coat cement plaster on smooth plastered walls , PLUS one coat plaster primer and two coats Plascon Wall paint on external side.  M2  60  
Subtotal EXTERNAL ENVELOPE 