# Composite Rate Build Up for Foundations – Approximate Quantities in Elemental Estimate Layout

Composite Rate Build Up – Foundations

The Elemental Estimate layout and grouping of items will be used in this example. There are principles that you have to follow when building up composite rates for Approximate Quantities. We are going to illustrate a composite rate build-up for Foundations:

Excavate trench 600mm wide and 700mm deep, with 200mm thick concrete footings, 230mm foundation brickwall 800mm high and facebricks on plinth 300mm high.

Step 1

First, you have to determine the Group unit of measurement. When you are measuring Foundations in Elemental or Approximate Quantities estimating, the group unit of measurement is the metre (m).

Step 2

The second step is listing all associated Bill items that can be mapped to Foundations by length. These are:

• Trench Excavation – (m3) Rate – R27.50
• Risk of collapse/Earthwork support – (m2) Rate – R2.00
• Compaction – (m2) Rate – R5.00
• Ant Poisoning to bottoms and sides of trench – (m2) Rate – R7.00
• Backfilling  – (m3) Rate – R35.00
• Cart-away surplus material from excavations – (m3) Rate – R30.00
• Concrete footings – (m3) Rate – R1200.00
• One Brickwall in Foundations  – (m2) Rate – R235.00
• 150mm wide Brick reinforcement – (m) Rate – R2.50
• Facings on plinth area – (m2) Rate – R50.00
• DPC – (m2) Rate – R7.00

Step 3

Since your Group unit is the metre (m), you should convert the Bill item rates to Cost per Metre.

 Rate Build UpGROUP – FOUNDATIONS Rate – Cost Per Metre (m)  Rands Rate – Cost Per Metre (m)  Rands 1m of Trench Excavations: 600 x 700 x 1000 0.6 x 0.7 x 1 = 0.42m3 0.43m3 x R27.50 = R11.83 11.83 1m of Earthwork Support: (700)2 x 1000 (0.7) 2 x 1 = 1.44m2 1.44m2 x R2.00 = R2.88 2.88 1m of Compaction: 600 x 1000 0.6 x 1 = 0.6m2 0.6m2 x R5.00 = R3.00 3.00 1m of Ant Poisoning: Bottom 600 x 1000 = 0.6 x 1 = 0.6m2 0.6m2 x R7.00 = R4.20 4.20 Sides (700)2 x 1000 = (0.7)2 x 1 = 1.4m2 1.4m2 x R7.00 = R9.80 9.80 1m of Backfilling: 600 – 230 = 370 700 – 200 = 500 370 x 500 x 1000 0.37 x 0.5 x 1 = 0.185m3 0.185m3 x R35.00 = R6.48 6.48 1m of Cart-away from Excavations: 700 – 200 = 500 500 x 230 x 1000 0.5 x 0.23 x 1 = 0.115m3 0.115m3 x R30.00 = R3.45 3.45 1m of Concrete Footings: 600 x 200 x 1000 0.6 x 0.2 x 1 = 0.12m3 0.12m3 x R1200.00 = R144.00 144.00 185.64 1m of One Brickwall in Foundations: 800 x 1000 0.8 x 1 = 0.8m2 0.8m2 x R235.00 = R188.00 188.00 1m of 150mm wide Brick reinforcement: 1m = R2.50 2.50 1m of Facings on plinth area: 300 x 1000 0.30 x 1 = 0.30m2 0.30m2 x R50.00 = R15.00 15.00 1m of DPC: 230 x 1000 0.23 x 1 = 0.23m2 0.23m2 x R7.00 = R1.61 1.61 207.11 Composite Rate – FOUNDATIONS 392.75

The composite rate for FOUNDATIONS is R392.75 per metre.

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