Every contractor ends up doing estimating at some point, usually late at night, usually squeezed between running current jobs and looking at a new set of drawings that just landed. It's a specific skill, and doing it badly costs you more than doing it slowly.
Part of the problem is that the role of a cost estimator is often misunderstood, even by the people doing it. It gets treated as arithmetic: measure, multiply, add up. The arithmetic is the smallest part. The real work is judgement, and judgement needs time and attention that a site manager or business owner rarely has spare.
The role of a cost estimator is more than adding up quantities
A cost estimate worth pricing off pulls together the drawings, the specification, current material and labour rates, and a realistic read of the site, then turns all of that into numbers you can stand behind. Miss the specification detail and your quantities are wrong before you've priced a single line.
So a good estimator is really doing four jobs at once. Reader, spotting what the drawings show and what they leave out. Measurer, turning that into quantities. Pricer, applying rates that suit this particular job. And sceptic, asking what could go wrong and whether the price allows for it.
Drop any one of those and the estimate suffers. Most rushed estimates drop the first and the last.
The sceptic part pays for itself. Asking "what if the ground is worse than the site investigation suggests?" or "who's paying for temporary propping?" before you price is how you avoid finding out the answer after you've signed.
What the job involves, start to finish
On a typical tender, the work runs in roughly this order:
- Read the full tender package. Drawings, specification, contract terms, tender instructions. Note anything missing or contradictory.
- Raise queries. Send questions to the client or designer before the query deadline rather than guessing.
- Measure the quantities. Take off every element to NRM2, organised so it can be priced and checked.
- Get subcontract and supplier quotes. Send out the relevant packages, then check what comes back for exclusions and gaps.
- Build up the rates. Labour, plant and materials for the work you do yourself, priced for the actual site and programme.
- Price preliminaries. Site set-up, welfare, supervision, scaffold and the rest, against a realistic programme.
- Check and qualify. Review against the drawings, then write down the assumptions and exclusions the price depends on.
That's a lot to fit in around a full working week, which is why the steps that get squeezed are always the reading, the queries and the checking.
The measuring is where most errors start
Get a quantity wrong on a drawing and every rate you apply afterwards compounds that error. This is why a proper take-off, broken down against NRM2, matters more than the software used to produce it. The structure is what stops errors hiding in a big total.
Say the floor area of an extension is measured at 40 m2 when it's really 44 m2. That's 4 m2 missing, and it doesn't stay in one line. It runs through the slab, insulation, screed, floor finish, ceiling, and every other item measured off the same area. One wrong dimension becomes a dozen wrong lines, each looking perfectly sensible on its own.
A rate can only be as right as the quantity it's multiplied by. Most bad estimates were measured wrong long before they were priced wrong.
It runs the whole length of the job, not just the tender
A decent estimate isn't a one-off document you produce and forget. It should hold up when the job's running, when a variation lands, when someone on site asks why an item costs what it costs.
If your original figures were rushed, you'll be defending guesswork months later instead of a proper measured position. If they were built properly, the estimate becomes the reference for valuations, variations and the final account. The same quantities that won the job are the ones you measure progress against.
This is the part of the role of a cost estimator that tends to be forgotten once the tender is sent. The estimate's working life is the length of the contract, not the length of the tender period.
Contractors who separate this work price better
The contractors who win consistently tend to separate the estimating from the site running. Not because they can't do it themselves, but because doing both at once means one of them suffers. Handing the measuring to someone dedicated to it frees you up to run the job you've already got and price the next one properly.
There are a few ways to do that:
- An in-house estimator. Makes sense once you have a steady flow of tenders to keep them busy.
- A freelance estimator. Flexible, though availability can be patchy when you need them most. There's more in freelance estimator or estimating service, what actually differs.
- An estimating service. You send drawings, you get back measured quantities and a priced estimate, for a fee agreed in advance.
Whichever route you take, you still own the final price. The estimator gives you a measured, checked base. You add your knowledge of your own costs, your trades and how much you want the job.
A test for whoever does your estimating
Take your last lost tender and your last won tender. For each, could you show someone where every major figure came from without opening a different file or relying on memory? If yes, your estimating is working, whoever does it. If not, the job isn't getting the time it needs, and it's probably costing you more than you think.
Our construction estimating services measure quantities from your drawings and price them on current UK rates, local to the job and broken down to NRM2, so you've got a figure you can defend at tender and on site.