The secret of estimating lies in building "Standard Rates" which will provide accuracy, consistent, flexibility and time savings. When completed they will stand the test of time and can be adjusted in accordance with technology changes.

A Standard Rate is a combination of building materials, which are required in varying proportions to carry out a task. The quantities may be from different units of measurement, but must be converted to reflect the actual unit of measurement for the particular function.

For example drainage is quoted in metre/feet, yet pipe is sold in various lengths and only in a few cases are they sold in one- metre/foot increments. Solvent cement for DWV pipe is sold by the tin and needs to be converted to a quantity of a tin per metre/foot.

Excavator is calculated by the cubic metre/yards and must reflect as a cost per metre/foot while bedding material is purchased by the cubic metre/yard or by the tonne/ton, which is also converted to a cost per metre/foot.

The benefit to formulating standard rates is, there will only be a need to build them once, and they are then used for a lifetime only needing to be altered when technology changes. If a toilet suite is to be installed on a concrete floor and fixed to a brick or block wall, whether being installed in a residence or a 30 storey building it will require a pan, cistern, seat, fixings etc. The only variation will be the labour content. In a house it will be marginally faster (12%) to install than it will be on the 30th floor of a high-rise building

Build a Standard rate

1	Identify the task or function eg: copper cold water services 32mm/1.25" fixed to concrete.
2	As copper pipe is sold in six metre/20foot lengths, and contractors quote pipe per lineal metre/foot including waste, brackets, fixing and labour a conversion is necessary.

The formula to calculate the proportion of one length of pipe required per lineal metre is: P = (1/L) + W, Where

P	one metre/foot of pipe, as a proportion of the manufactured length. Expressed as a decimal.
1	one length of pipe
L	the manufactured length of the pipe in meters
W	Waste factor (in this case 10%)

The 32mm copper pipe is manufactured in six metre (20') lengths.
P = 1/6 + 10%
P = 0.18 of a length (18%)

Or

1/20 + 10% waste
= 0.055 of a length
= 5.5% of a length

The process is repeated for each item, in the case of copper pipe solder would be converted to a proportion of one stick required for one joint or a quantity per metre/foot. The same applies to the brackets and fixings.

4. Such standard rates should be made for:

• DWV copper stacks
• DWV PVC stacks
• Cold water services
• Hot water services
• Fire services
• Gas services
• Drainage sewer
• Drainage storm water