Unlimited users, never per-seat30+ modules, one account14-day trial, no cardQR clock-in, server timedOne flat monthly feeCyber Essentials PlusFree migration includedCDM 2015 built inUK hosted, UK supportInsurance expiry checked nightlyAndroid and iOS appNo minimums, cancel anytimeBookkeeping capture, by email99.97% uptimeExport everything, anytime
Start the 14-day trial
Book a demo→
Insight · Choosing software

Where spreadsheet
job costing breaks.

Not when it gets complicated. When two people open it, when committed cost is not in it, and when the true position is a week old by the time anybody has assembled it.

Published ·5 min read·Written by Unibuild

Spreadsheet job costing fails on four specific properties rather than on complexity: committed cost is not in the file, two people cannot safely edit it at once, the figures are transcribed from elsewhere so they lag, and no version is authoritative. The result is a cost position that is accurate about last week and confident about today.

Spreadsheets are not the problem

Excel is a remarkable tool and most contracting businesses in this country are run on it competently. It is fast, everybody can use it, it costs nothing extra, and it bends to whatever a commercial manager needs it to do on a Tuesday. A firm that has built a good cost model in it has built something real.

What follows is not an argument that spreadsheets are amateurish. It is an argument that a contractor's cost position has four properties that a single file cannot hold, and that the failure is structural rather than a matter of how carefully anybody works.

One. Committed cost is not in the file

This is the big one and it causes more surprises than the other three together.

Most job cost spreadsheets are built from invoices, because invoices are what arrive and what get entered. But a contractor commits money long before it is invoiced. You issue a purchase order for £40,000 of materials on Monday and the invoice appears six weeks later. You instruct a subcontract package for £120,000 and the first application comes at the end of the month.

Until those documents land, the spreadsheet shows the job in better health than it is. Not by a random amount, and not in a random direction: it always understates, and it understates most at exactly the point in a job when the commitments are largest and the invoices have not caught up.

A cost sheet built from invoices is not a picture of the job. It is a picture of the post.

Firms usually know this and compensate with a mental allowance. That works while one person carries the whole job in their head, and stops working the moment there are eleven jobs and three people.

Two. Two people cannot safely have it

The moment more than one person needs to update the file, one of three things happens. Somebody works on a copy and the versions diverge. Somebody waits, so the file is out of date by however long they waited. Or it goes into a shared drive with simultaneous editing, and a formula gets overwritten by a paste that nobody notices for a fortnight.

That third one is worth dwelling on because it is silent. A broken formula in a corner of a large sheet does not announce itself. It produces a number that looks like a number, and the report built on it looks like a report.

Three. Everything in it was typed twice

Hours come off a timesheet or a WhatsApp message and get typed in. Invoices come from the accounts package and get typed in. Applications get typed in from a different sheet. Plant charges come off a hire schedule and get typed in.

Two costs follow. The obvious one is the time, which is somebody's week every month. The less obvious one is the lag: every transcription step adds delay, and by the time all four sources are in, the earliest of them is a fortnight old. That is the mechanism behind the sentence on our directors page, that the true position of a job lives in four places and assembling it takes a week.

Four. No version is the version

Ask a firm running on spreadsheets which file is authoritative and you get a pause. There is the one on the shared drive, the one the QS is working on, the one that was emailed to the director on Friday, and the one somebody took home. All four are plausible and none is marked.

The practical consequence arrives in a meeting, where two people have different numbers for the same job and the discussion becomes about whose sheet is right rather than about the job.

When it actually starts to hurt

Not at a headcount and not at a turnover. Three thresholds, and firms usually cross them without noticing.

  • When more than one person needs the answer. One commercial manager with one file is coherent. Two people is where version drift starts.
  • When jobs outlast memory. Everything works while somebody can hold the exceptions in their head. At about eight or ten concurrent jobs that stops being possible, and the sheet has to carry what the person was carrying.
  • When somebody outside sees the number. A bank, an insurer, a prospective buyer, or a client asking for a cost report. That is when the difference between a figure and a defensible figure becomes real.

If you are staying on spreadsheets

Which is a perfectly reasonable decision for plenty of firms. Three changes remove most of the risk without changing anything else.

Add a committed cost column and populate it at the point of order rather than invoice, even if it is a manual entry. Nominate one file as authoritative, put the date in the filename, and make everybody else read-only. And reconcile to the accounts package monthly rather than at year end, because a difference found in month two is a data entry error and the same difference found in month eleven is an investigation.

Where this touches the platform

Each of the four failures maps to something Unibuild does differently, and it is worth being specific rather than general. Cost is captured at commitment: an order is a cost against the job from the moment it is issued rather than from the moment it is invoiced. Everything sits on one record that people are granted access to page by page, so there is no copy and no authoritative-file question. Hours arrive from a QR clock-in against the job on the day they are worked rather than being retyped from a sheet, and applications are built from work already measured. Gross applied and gross balance are calculated as at each row's own date, so a question about March is answered as at March. The boundary: it is not an accounting system, your accounts package stays, and reconciling the two is still somebody's job.

Cost control For directors Financial and invoicing Timesheets and workforce

Where to start, on Monday

Take your largest live job and write down two numbers: the cost your spreadsheet shows, and the total value of purchase orders and subcontract packages you have issued on it that have not yet been invoiced. The second number is the size of the gap you have been carrying in somebody's head.

If that gap is small, your spreadsheet is doing its job and this article is not about you. If it is large enough to change how the job looks, you now know the number, which is a better position than yesterday whatever you decide to do about it.

Asked most often

The follow-up questions.

What replacing it costs is set out in what construction software actually costs.

Why does job costing in Excel stop working?+
On four structural properties rather than on complexity: committed cost is not in the file because it is built from invoices, two people cannot safely edit it at once, every figure is transcribed from another system so the position lags, and no single version is authoritative. The result is a cost position that is accurate about last week and confident about today.
What is committed cost and why does it matter?+
Cost a job has irrevocably taken on but not yet been invoiced for, such as an issued purchase order or an instructed subcontract package. A cost sheet built from invoices excludes it, so it always understates the position, and it understates most at the point in a job when commitments are largest and invoices have not caught up.
At what size does a contractor outgrow spreadsheet job costing?+
Not at a headcount or turnover, but at three thresholds: when more than one person needs the answer and version drift starts, when jobs outlast memory at roughly eight to ten concurrent jobs, and when somebody outside the business sees the number, such as a bank, insurer, buyer or a client asking for a cost report.
How can I make spreadsheet job costing safer without replacing it?+
Three changes remove most of the risk. Add a committed cost column populated at the point of order rather than invoice, even manually. Nominate one authoritative file, put the date in the filename and make everyone else read-only. And reconcile to the accounts package monthly, because a difference found in month two is a typing error while the same difference in month eleven is an investigation.
Are spreadsheets unprofessional for construction cost control?+
No. Plenty of contracting businesses are run competently on them, and a well-built cost model in Excel is a real asset. The argument against is structural rather than about care or skill: a contractor's cost position has properties a single file cannot hold, principally committed cost and concurrent change by more than one person.
Read next

More from Insights.

Winning work··5 min readGetting on a main contractor's approved listThe application is the easy half. What decides it is the evidence pack behind it, and what gets a firm quietly dropped afterwards is rarely the work.Read it →Winning work··6 min readSSIP, CHAS, Constructionline and what replaced PAS 91An acronym map with the money attached. Which schemes are health and safety only, which are full pre-qualification, what mutual recognition actually saves you, and why PAS 91 is no longer the answer.Read it →Tax and CIS··5 min readWhat counts as construction work under CISThe included list is wider than most firms assume and the excluded list catches out exactly the trades that read it. Plus the mixed contract rule, which decides more cases than either list.Read it →Tax and CIS··5 min readCIS monthly returns, the date and the penaltiesThe nineteenth, every month, whether or not you paid anybody. What the penalty ladder actually looks like, and the declaration on the return that carries more weight than the figures.Read it →Tax and CIS··5 min readEnd user statements, and what they switch offIt has to be in writing, it comes from your customer rather than from you, and without it the reverse charge applies by default. What the statement says and where it belongs.Read it →Health and safety··5 min readThe certificates that expire without anybody noticingInsurance, cards, plant inspections, training and first aid all run out on different dates, and nothing about your file changes on the day one of them does. What has to watch them.Read it →Health and safety··5 min readWhen an HSE inspector turns up on siteWhat they can do, what they ask to see and in what order, what a Notification of Contravention means, and what the visit can cost you at £188 an hour.Read it →Health and safety··5 min readRIDDOR, what has to be reported and by whenThree different clocks run on three different categories, and the one firms miss is the fifteen days, which counts from the accident rather than from the day you realised.Read it →Health and safety··5 min readWhen a job becomes notifiable, and who tells the HSETwo thresholds, either of which triggers it, and a duty that sits with the client rather than with you. How to work out whether your job crosses them.Read it →Health and safety··5 min readWhich CSCS card, and who actually checks itSeven colours, different qualifications behind each, and a five year clock on most of them. What each card is for, and why it is not a legal requirement but still stops you at the gate.Read it →Choosing software··6 min readWhy WhatsApp fails as a site recordIt is the system most sites actually run on, and it works right up until somebody asks a question about March. Six specific failures, and the one that arrives when a person leaves.Read it →Choosing software··6 min readChoosing construction management software, and what to actually compareEvery product demos well. A buyer's checklist written to be useful even if you buy from somebody else, including the five questions vendors answer badly.Read it →Choosing software··5 min readXero for contractors, and where the accounts package stopsIt handles CIS properly and it is a good ledger. What it is not built to hold is the job: the measured schedule, the valuation, the retention and the cost you have committed but not yet been invoiced for.Read it →Choosing software··5 min readDocument control, and the revision everybody was working toBuilding to a superseded drawing is expensive, common, and almost never anybody being careless. What has to be true for the right revision to reach the person holding the tool.Read it →Getting paid··5 min readAn application for payment that does not come back rejectedFour reasons account for most rejections, and none of them is the price. What the document has to contain, what has to sit behind it, and the date that matters more than the total.Read it →Getting paid··5 min readGetting paid for variations you were told to get on withThe entitlement is rarely the problem. The evidence is. What stands up when the instruction was verbal, and the one email that changes the argument.Read it →Getting paid··5 min readWhen a missing notice hands you the moneyAn adjudication that asks nothing about what the work was worth, only whether the notices were served. What it wins, and the second adjudication that usually follows it.Read it →Getting paid··5 min readStopping work for non-payment, without breaching your contractA statutory right with narrow conditions and real leverage. What has to be true before you can use it, what the notice must say, and what walking off without one costs.Read it →Getting paid··5 min readCharging interest on a late payment, and the sums nobody claimsStatutory interest runs at eight per cent above base, and a fixed compensation sum sits on top of it that almost nobody asks for. Both are automatic entitlements rather than favours.Read it →Getting paid··6 min readWhat the Construction Act actually gives youSix rights that apply whether or not your contract mentions them, and whether or not anything was ever signed. What each one is, and where it stops.Read it →Subcontractors··6 min readVetting a subcontractor before you instruct themNine checks, what each one is actually protecting you from, and the two that firms skip and then discover matter. Most of it is twenty minutes and free.Read it →Reducing risk··6 min readCredit checking the firm above you, free, in twenty minutesEverything you need is public and none of it costs anything. Filing history, charges, director record, county court judgments, and the payment data large firms are now compelled to publish, including what they do with retention.Read it →Commercial··5 min readQuote or estimate, and which one binds youOne is an offer that becomes a fixed price the moment it is accepted. The other is an informed guess. Almost nobody says which they are sending, and the word at the top of the page is not what decides it.Read it →Health and safety··5 min readWhen you become the principal contractor without being toldThe duty attaches to a role, not to the size of the firm, and a second contractor arriving on site is enough to trigger it. What lands on you, and what happens when the client never appointed anybody.Read it →Choosing software··6 min readWhat construction software actually costsThe monthly figure is the part everyone compares and the smallest part of the bill. Setup, migration, the annual uplift, and the licences you ration because they are charged per person.Read it →Tax and CIS··8 min readThe VAT reverse charge, and who accounts for the VATFive years in and it still catches firms out on every second invoice. When it applies, when it does not, the written statement that switches it off, and the wording your invoice has to carry.Read it →Tax and CIS··7 min readReclaiming CIS deductions, and the money sitting with HMRCA limited company gets its deductions back through payroll rather than through its Corporation Tax return, and only if somebody files the right submission every month. Where the money goes, and how to stop it piling up.Read it →Commercial··7 min readThe gap between doing the work and having the moneyWages go out weekly, materials at thirty days, and the money comes back at sixty. Retention, CIS and the reverse charge each take a slice on the way. Why a job that made a profit can still run a firm out of cash.Read it →Getting paid··8 min readWhen the contractor above you will not payThe remedies run in a fixed order and each one costs more than the last. What to do first, what every step is worth, and the rung most disputes never get past.Read it →Getting paid··8 min readPay less notices, and the timetable behind themFour dates govern every interim payment in UK construction, and statute sets them rather than goodwill. What each one is, how to work them out on your own job, and what a late notice costs the party that served it.Read it →Getting paid··6 min readPay when paid, and why it does not bind youMaking your money conditional on somebody else being paid has been ineffective in UK construction since 1998. The clause is still written into contracts, still quoted down the phone, and still works on firms that do not know.Read it →Site team reviewing a risk assessment and method statement on a UK construction siteHealth and safety··7 min readRAMS that hold upWhat an inspector is actually looking for in a risk assessment and method statement, and the difference between a document that exists and one that is doing its job.Read it →Retention and the money that goes missing after practical completionCommercial··6 min readRetention, and the money that goes missing after practical completionWhere cash quietly disappears between the last valuation and the release of the second half of retention, and the four dates that decide whether you ever see it.Read it →Why field rollouts stall in week threeImplementation··6 min readWhy field rollouts stall in week threeMost site software is not rejected. It is quietly outlived by the paper route nobody switched off. What the firms that got it to stick did differently.Read it →
Next step

See cost at commitment, not at invoice.

Book a 45-minute demo → See cost control
Phone · UK hours
+44 7587 557546
Email
[email protected]
More writing
All insights
What it costs
Pricing
WhatsApp us, someone is available now