Every commercial cleaning company in London seems to keep the logo somewhere near the footer. A small square, usually parked beside the Living Wage mark and something about being SafeContractor approved. ISO 9001. It reads as official because it is official, and yet most of the facilities managers who write “must hold ISO 9001” into a tender couldn’t tell you what the thing certifies (I’ve asked; they mostly can’t).

The standard has been shorthand for “serious company” for so long that the shorthand has quietly replaced the meaning. Worth pulling the two apart before you rest a decision on it.

What does ISO 9001 actually certify?

Not that a company cleans well. This surprises people the first time they hear it said plainly. ISO 9001 is a quality management system standard, and the word doing the work in that phrase is management, not quality in the sense you’d assume from the name. It certifies that a business has written down how it does things, and that it broadly does them the way it wrote them down.

The standard is deliberately generic. The same ISO 9001:2015 framework applies to a sourdough bakery in Hackney, a firm of patent attorneys off Chancery Lane, and a company that sends twelve cleaners into a Canary Wharf tower at half five in the morning. It says nothing about what good looks like in any of those trades. The 2015 revision leaned harder into what the drafters call risk-based thinking — the idea that an organisation should anticipate where things might fail and build controls before they do — and it sits on top of the old plan-do-check-act loop that has underpinned the document for decades. Define your processes. Monitor them. Act when something goes wrong. Repeat, and keep the records that prove you repeated.

An auditor turning up for the annual surveillance visit isn’t checking your skirting boards. They’re checking whether the method statement for cleaning a kitchenette exists, whether staff have been trained against it, whether the complaint from the third floor got logged, and whether anyone closed it out. Where the auditor finds a gap, they raise a nonconformity, and the contractor has to show corrective action before the certificate stays valid. A good audit day for a cleaning contractor is a day of producing folders, not a day of impressing anyone with a shine. The best-run firms treat that as a genuine discipline. Plenty of others treat it as a fortnight of frantic photocopying once a year and forget it exists the moment the auditor’s car pulls away.

The gap between the manual and the mop

Here’s where it gets slippery. The certificate confirms the paperwork is in order. It does not, and structurally cannot, confirm that the cleaner working a Holborn office at six in the morning follows the method statement pinned inside the cupboard. Systems describe intentions. The overnight reality on a given site comes down to supervision and whether anyone senior has physically visited the building since the contract was signed (often the answer is no).

Why do so many London tenders demand it?

Procurement. Almost entirely procurement.

If you’ve watched a cleaning contract go out through a London borough — Camden, Westminster, take your pick — you’ll have seen ISO 9001 sitting in the mandatory criteria, usually bundled with ISO 14001 for environmental management and increasingly ISO 45001 for health and safety. The certificate works as a filter. It lets a procurement officer cut a field of forty bidders down to twelve without reading forty submissions, and it gives them something defensible to point at if the appointment is ever challenged at review.

NHS trusts require it. Universities require it — I’ve seen it written into tenders from a couple of the Bloomsbury colleges, where the estates teams manage listed buildings and won’t look at an uncertified contractor. Large managing agents running Grade A stock in the City write it in as standard, then fold cleaning into a framework agreement that gets re-competed every three or four years. The cumulative effect is that ISO 9001 has become a cost of entry for anyone chasing contracts of any size, rather than a signal of anything a cleaner would recognise as competence at the sharp end.

The procurement filter

Which creates a slightly perverse incentive. Contractors get certified because they must be certified to bid, not because the process ever improved their cleaning. The badge is bought to open a door, and once the door is open it mostly stops mattering to anyone until the next audit falls due.

What’s the difference between accreditation and certification?

People use the two words as though they mean the same thing. They don’t. This one is worth getting right, because the “ISO 9001 accredited” phrasing you see across cleaning websites — including, I’d wager, on the very sites that sell this stuff hardest — is, strictly speaking, wrong.

A cleaning company is certified to ISO 9001. The body that issues the certificate is accredited — in the United Kingdom, by UKAS, the United Kingdom Accreditation Service, the sole national accreditation body recognised by government. So the technically correct construction is “ISO 9001 certified by a UKAS-accredited body.” Nobody writes that on a homepage. But the distinction has teeth, and here is where they bite.

A company can pay a non-accredited certification body — and there are plenty operating in exactly this space — for a certificate that carries the ISO 9001 name and none of the third-party rigour. It looks identical on a website. The same rough logo, the same reassuring number of digits. The audit behind it may have amounted to a questionnaire and an invoice.

UKAS and why the logo matters

The tell is the crown-and-tick UKAS mark alongside a certificate number you can check against a public register. A genuine certificate names the accredited certification body, carries that reference, and states an expiry date on a three-year cycle with surveillance audits in the intervening years. If a contractor sends you a certificate with no UKAS reference anywhere on it, the certificate is worth roughly what a certificate from a certificate mill tends to be worth (very little, is the polite version).

Does the badge tell you whether the toilets actually get cleaned?

No. And I’ll go further than most people in this trade are willing to.

For a single London office — say a forty-desk floor above a shop on Clerkenwell Road — the ISO 9001 status of your contractor tells you almost nothing useful about the standard of cleaning you’ll get on a wet Tuesday in November. What it tells you is that the company is big enough and organised enough to sustain a quality management system, which correlates loosely with the kind of stability that means they probably won’t fold mid-contract. That correlation is real. It is also weak, and the industry oversells it on purpose.

The honest version runs like this. Cleaning quality on a specific site is driven by three unglamorous variables: how much time the cleaner is actually given, how well they are supervised, and how high the staff turnover sits on that account. Not one of those appears on an ISO certificate. A certified national contractor spreading a cleaner too thin across too many buildings will lose, on any measure a tenant cares about, to a small uncertified firm that gives the same floor an extra forty minutes and a supervisor who genuinely turns up. I have watched that exact swap play out.

There was a marketing agency near Old Street — one of those converted warehouse floors just off Rivington Street, exposed brick, far too many pot plants — that dropped a well-known certified contractor for precisely this reason. The paperwork had been immaculate. The kitchen bins told a different story by Thursday most weeks. The replacement firm held no ISO anything and kept the place genuinely spotless, though I’ll concede the sample size there is one office and an alarming number of pot plants.

The certificate measures the machine that produces the service. It does not measure the service. On a large multi-site account the two tend to move together, because you simply cannot run forty buildings competently without systems holding the whole thing up. On one floor in EC1, they come apart constantly, and the badge on the wall does nothing to hold them together.

Reading a certificate properly

If you are going to ask for one, read the scope statement. It’s the line almost everyone skips. A certificate’s scope might read “the provision of commercial cleaning services” — fine, that covers you — or it might be quietly narrowed to a specialism or a region that doesn’t cover the work you are buying at all. The scope is the one place a certificate is obliged to tell the truth about what it actually covers, and it sits printed directly under the company name. Read it before the logo.

What should a London office ask for instead?

Ask about the things the badge cannot tell you. Staff turnover on their comparable existing accounts. Who supervises the site and how often that person physically attends rather than phones. Whether they have written a method statement specific to your building or intend to reuse a template with your address pasted at the top. What happens under TUPE if you are inheriting an existing cleaning team from the outgoing contractor, and whether the people who currently know your building will still be the people cleaning it in three months. Those answers predict your experience far better than any logo does.

Beyond the badge

Treat ISO 9001 as sensible hygiene for a large tender and close to irrelevant for judging a single office contract. It is a reasonable thing to require and a poor thing to feel reassured by.

The certificate itself, when it finally lands in your inbox, is usually a single laminated sheet of A4 with a UKAS number in one corner and an expiry date three years out. Check the date. Then go and look at the bins.