My Project Estimating · Bill of Quantities
Most disputes on site don't start because the total price was wrong. They start because nobody can say what the total was actually made up of. A single lump sum tells the client's QS nothing, and it tells your own site manager even less when a variation lands and someone has to argue what rate to use. Breaking a price down by element isn't paperwork for its own sake, it's what saves you an argument in month four.
Materials and labour are the obvious ones and most contractors have those covered. Where estimates go wrong more often is the indirect side, site management, welfare, plant standing time, attendances on subcontractors, and the general overhead of running the job week to week. If these are lumped in with measured work, nobody can tell later whether a variation should carry a share of them or not.
A contingency figure needs a reason behind it, not a round number picked because it felt safe. Ground conditions, access restrictions, and the state of the existing information all push that figure up or down. Write down why the contingency is what it is when you price the job, because you'll be asked to justify it later, either by your own director or by the client's QS.
A breakdown only earns its keep if the site team can actually use it once the job starts. That means quantities and rates that trace back to NRM2 elements and to specific drawings, so that when a variation comes in your QS can price it against the same base rather than starting from scratch.
The best time to build a proper breakdown is before the price goes out, not after the contract is signed and you're trying to reconstruct it from memory. If you want to see the level of detail we work to, See a sample estimate. If you've got a job to price, Send your drawings and we'll build the breakdown properly the first time.
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