Apr 24

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

 

CompositeRate_External Envelope_Windows

 

Composite Rate Build Up – Windows

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 Windows:

Wispeco window type NC22 size 2000 x 949mm high, including NBP 2 burglar bars to all sections, precast concrete lintels 110x75mm, Everite Nutec  fibre-cement 15 x 114mm wide internal cills and 15 x 175mm wide external cills, 18mm thick pelmets, curtain tracks, cement plaster to reveals, paint on plastered reveals, glazing and paint on window frame/burglar bars.

Step 1

First, you have to determine the Group unit of measurement. When you are measuring Windows in Elemental estimating, the group unit of measurement is the square metre (m2).However, in Approximate Quantities and for rate build-up calculation purposes, it is more convenient to use the number (No.)

Step 2

The second step is listing all associated Bill items that can be mapped to Windows by area. We are linking these items to Window type NC22 size 2000x949mm high. These are:

  • Window frame NC22 including burglar bars  – (No.) Rate – R625
  • Glass – (m2) Rate – R235
  • Painting on window frame/burglar bars (1 coat primer and 2 overcoats)– (m2) Rate – R30

Step 3

The third step is listing all associated Bill items that can be linked to Window type NC22 size 2000x949mm, even though they can’t be mapped to the area:

  • Lintels – (m) Rate – R38.00
  • External cills – (m) Rate – R65.00
  • Internal cills –  (m) Rate – R45.00
  • Pelmets – (m) Rate – R25.00
  • Curtain tracks – (m) Rate – R35.00
  • Cement plaster to reveals (narrow widths) – (m2) R30.00
  • Painting to reveals (narrow widths) – (m2) R30.00

Step 4

Since your Group unit is the number (No.) you should convert the Bill item rates to Cost per Window.

Rate Build Up

GROUP – WINDOWS

Rate – Cost Per Window NC22 (No.)  Rands
Approximate Elemental
1No. Window frame NC22:    
1No = R625 625.00
Glass for 1No. Window NC22:
1No = 2000 x 949mm = 2 x 0.949 = 1.898m2
1.898m2 x R235 = R446.03 446.03
Paint on 1No. Window NC22:    
Paint on frame and burglar bars both sides:
1.898m2 x R30 = R56.94 x 2 = R113.88 113.88 1184.91
 
Lintels on Window NC22:
2000 + 2(150) = 2300mm = 2.3m    
2 No. 110x75mm lintels on 220mm one brickwall
2.30 x 2 = 4.6m
4.6 x R38 = R174.80 174.80
External Cills on Window NC22:    
Window width – 2000mm
2.00 x R65 = R130 130  
Internal Cills on Window NC22:  
Window width – 2000mm  
2.00 x R45 = R90 90  
Pelmets on Window NC22:  
Window width – 2000mm  
Length of pelmet = 2000 + 2(150) = 2300  
2.3 x R25 = R57.50 57.50  
Curtain Tracks on Window NC22:  
Length of Curtain Track = Pelmet Length – (Pelmet Thickness x 2)  
L= 2300 – 18(2) = 2264mm  
2.264 x R35 = R79.24 79.24  
Cement Plaster to Reveals Window NC22:  
Internal side = (2 + 0.949)2 = 5.898m  
5.898 x 0.11 = 0.649m2  
0.649 x R30 = R19.46 19.46  
External side = 2+(0.949×2) = 3.898m  
3.898 x 0.11 = 0.429m2  
0.429 x R30 = R12.86 12.86  
Paint to Reveals Window NC22:  
Internal side:  
0.649 x R30 = R19.46 19.46  
External side:  
0.429 x R30 = R12.86 12.86 596.18
 
Composite Rate – WINDOWS 1781.09 1781.09

The composite rate for WINDOWS is R1781.09 per window (type NC22 size 2000 x 949mm).

Step 5

Convert Composite Rate to Cost Per Square Metre

You can convert this rate to Cost Per Square Metre for the Elemental Estimate:

Type NC22 Window size 2000 x 949,

Area = 2 x 0.949 = 1.898m2

Therefore, cost is R1781.09 per 1.898m2

Elemental Rate = R938.40 per m2

 

Elemental Layout and Grouping

Items which go into the element EXTERNAL ENVELOPE and component Windows are stated in the description:

 

 

Unit Quantity Unit Rate Cost/m2 Subtotal Cost
EXTERNAL ENVELOPE

 

Windows:

 

Wispeco window type NC22 size 2000 x 949mm high, including burglar bars to all sections, PC lintels 110x75mm, fibre-cement 15 x 114mm internal cills and 15 x 175mm external cills, 18mm Thick pelmets, curtain tracks, plaster and paint on reveals, glazing and paint on window frame/burglar bars b/s.

 

M2 938.40
Subtotal EXTERNAL ENVELOPE (Windows)

 

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  1. […] to Cost per Square Metre, we have to use principles that are used in building up composite rates for Windows. In this case, the flat area between trusses (7.020×1.200)m should be treated as a single […]

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