Composite Rate Build Up for Roof and Ceilings – Approximate Quantities in Elemental Estimate Layout


CompositeRate_Roof and Ceilings


Composite Rate Build up – Roof

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 the Roof:

Roof construction: 6 x Double-pitched Truss Type 1, size 7020 x 1100mm high at maximum 1200mm centres, 114 x 38mm wall plates, 38x76mm diagonal bracing, longitudinal binders, roof covering 0.5mm thick IBR embossed galvanised profiled troughed steel sheeting fixed to 75x50mm timber purlins at 1200mm centres, including Super Sisalation Residential Grade 410 waterproof insulation laid taut over timber purlins at 1200mm centres and fixed concurrent with roof covering including galvanised steel straining wires at 275mm centres over purlins. Horizontal plasterboard ceilings 6.4mm thick x 1200mm wide boards with and including H-type pressed steel jointing strips and 38x50mm sawn softwood brandering at 400mm centres, plus paint to ceilings.

Step 1

First, you have to determine the Group unit of measurement. When you are measuring the Roof in Elemental or Approximate Quantities estimating, the group unit of measurement is the square metre (m2) on flat area or sloping surface. We will use the flat area.

Step 2

The second step is listing all associated Bill items that can be mapped to the Roof by area. These are:

  • IBR roof covering  – (m2) Rate – R155.00
  • Super Sisalation waterproof insulation – (m2) Rate – R25.00
  • Plasterboard ceilings including softwood brandering – (m2) Rate – R35.00
  • Painting to ceilings – (m2) Rate – R40.00

Step 3

The next step is listing all associated Bill items that can be linked to the Roof. These are items which cannot be mapped to the area.

Timber Roof Construction:

Truss Layout and Plan

Timber roof construction has members which are measured in metres and number. In order to convert the members of roof construction to cost per square metre, we should associate them to the flat area between two trusses. The trusses are spaced at 1200mm centres, and the base length of the truss is 7020mm. The flat area between trusses is 7.020 x 1.200m

  • Truss 7020 x 1100mm high – (No.) Rate – R900
  • 114 x 38mm wall plate – (m) Rate – R22.00
  • L-shaped angle brackets nailed to truss  and wall plate – (No.) Rate – R2.00
  • Purlin clips (Hurricane type) nailed to rafter and purlin – (No.) Rate – R2.00
  • Galvanised hoop iron roof tie 1500mm, built into brickwork and wrapped around wall plate – (No.) Rate – R2.00
  • 38x76mm Diagonal bracing – (m) Rate – R22.00
  • 38×50 Longitudinal binders – (m) Rate – R20.00
  • 75x50mm Purlins – (m) Rate – R19.00

Step 4

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