Composite Rate Build Up for Rainwater Downpipes – Approximate Quantities in Elemental Estimate Layout

Composite Rate Build up – Rainwater Downpipes

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 build-up for Rainwater Downpipes:

0,6mm Galvanised sheet iron Class Z 275

1. 75mm Diameter rainwater downpipe 3000mm long with brackets fixed to brick wall or concrete.
2. Extra over rainwater pipe for shoe (plinth offset) – No 12
3. Extra over rainwater pipe for eaves offset – No 12
4. Prepare, prime with a self-etching primer and apply one coat universal undercoat and one full coat high gloss enamel paint for exterior use:  On galvanised sheet iron Class Z 275 rainwater downpipes.
5. Extra over Eaves gutter for stopped end – No 12
6. Extra over Eaves gutter for outlet with nozzle for and jointed to 75mm diameter galvanised sheet iron downpipe including galvanised wire balloon grating – No 10

Step 1

First, you have to determine the Group unit of measurement. When you are measuring Rainwater Downpipes 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 Rainwater Downpipes by length. These are:

• Galvanised sheet iron 75mm diameter Rainwater downpipes  – (m) Rate – R50.00
• Two coats emulsion paint and one coat primer on Rainwater downpipes – (m) Rate – R36.00

Step 3

The third step is listing all associated Bill items which are linked to Rainwater Downpipes, but which cannot be mapped to downpipes by length:

1. Extra over rainwater pipe for shoe (plinth offset) – (No) Rate – R50
2. Extra over rainwater pipe for eaves offset – (No) Rate – R60
3. Extra over Eaves gutter for stopped end – (No) Rate – R45
4. Extra over Eaves gutter for outlet with nozzle for and jointed to 75mm diameter galvanised sheet iron downpipe including galvanised wire balloon grating – (No) Rate – R15

Step 4

Rate Build Up for items which can be mapped by length. Since your Group unit is the metre (m), you should convert the Bill item rates to Cost per Metre.

The composite rate for items which can be mapped to the Downpipe by Length is R86 per metre.

Step 5

Rate Build Up for items which are linked to the Rainwater downpipe, but which cannot be mapped to downpipes by length:

The composite rate for items which cannot be mapped to the Downpipe by Length is R56.67 per metre.

Step 6

Total Composite Rate for Downpipes is (86+56.67) = R142.67

Elemental Layout and Grouping

Items which go into the element ROOF and component Downpipes are stated in the description below: