Builder’s Clean, Sparkle Clean, Snagging Clean: Who Pays for Which One in a Cat B Fit-Out?

A project manager rang me from a half-finished floor off Bishopsgate wanting to know why her sparkle clean had come in at eleven thousand when the builder’s clean was four. She had assumed the second one would be cheaper, on the grounds that by then most of the mess would already be gone. It is the other way round, and the confusion behind that assumption costs London tenants more money each year than any other line I see argued over in a fit-out account.

What separates a builder’s clean from a sparkle clean?

The builder’s clean happens while the site is still a site. Hard hats on, first fix still going in, somebody drilling into a soffit above your head. The job is bulk removal – plasterboard offcuts, screed dust, silicone smears, protective film, the grey film that settles on everything within four hours of a wall being sanded. You are working around trades who will make more mess tomorrow, so nobody expects the result to survive the night.

The sparkle clean is a finishing trade. It comes after the last painter has left and before the client walks the floor, and it is measured against a completely different standard: the one where a facilities manager runs a finger along the underside of a desk rail in a meeting room off Charlotte Street and finds nothing.

Somebody is paying for it. The two jobs use different labour, different consumables, and in the second case a much higher tolerance for being made to come back.

Why the first clean is a waste-handling job, not a cleaning one

Half the cost of a builder’s clean in central London is disposal. Construction waste carries duty-of-care obligations and waste transfer documentation that ordinary office cleaning does not, and if your cleaning contractor is not a registered waste carrier the skip movements have to sit with the principal contractor anyway. Then there is the dust itself. Silica from cut screed and blockwork wants M-class extraction, not a Henry with a bag in it, and any contractor pricing a first clean on a Cat B without that kit is either cutting corners or has never worked one.

Who is contractually on the hook for the sparkle clean?

In almost every Cat B I have worked across Greater London – Stratford, Victoria, Ruskin Square down in Croydon – both the builder’s clean and the sparkle clean sit inside the main contractor’s preliminaries. They are priced into the tender sum before the tenant sees a schedule, which is precisely why tenants think they are getting them free. Somebody is paying for it, and that somebody is the tenant, at whatever margin the contractor has stacked on top.

This arrangement produces the single worst outcome in the trade. The main contractor holds the cleaning budget, the cleaning is the last thing to happen before a date with a liquidated damages clause attached, and by week thirty the programme has slipped eleven days. So the sparkle clean gets let to whoever answers the phone on Thursday for a number that would not cover the labour, never mind the machines.

I will say the unpopular thing: landlords should be naming the cleaning contractor in the licence to alter, the same way they name the M&E commissioning engineer. Fit-out glass gets destroyed in this country because a cheap crew turns up with steel scrapers and takes them to coated and toughened panes. Fabrication debris fused into the surface of toughened glass drags under a blade and leaves fine parallel scoring that no amount of polishing lifts. Replacement of a single large pane in a Bankside curtain wall will cost more than the entire clean did.

What “practical completion” does to your invoice

Practical completion is the hinge. Before it, cleaning is the contractor’s problem and comes out of the contract sum. After it, the building is yours, the insurance is yours, and every subsequent operative who walks through the door to fix something is bringing dust into a space you now own. Tenants sign the PC certificate on the strength of a floor that looks immaculate at four in the afternoon and then discover the meaning of that signature about ten days later.

Why does nobody budget for the snagging clean?

Because it is not a stage. It is the consequence of a stage, and consequences do not appear on Gantt charts.

Here is the shape of it. Practical completion happens. The snagging list runs to a hundred and forty items – a door leaf binding, six wonky sockets, an acoustic seal that whistles, three ceiling tiles that were cut short. Over the next four to six weeks, joiners and sparks and a plasterer come back in ones and twos to work through the list. Every one of them cuts, sands, drills or fills something. A single plasterer patching four bulkhead reveals in a Hammersmith office will put more fine dust into the air handling system in an afternoon than the whole of second fix did, because during second fix nobody had commissioned the AHUs yet.

That is the part that catches people. The mechanical systems were running by handover. So the dust from remedial works gets pulled into return air, distributed through the plenum, and dropped evenly over desks that already had monitors and keyboards on them. I have been called into an Old Street floor eight weeks after occupation where the client was convinced there was a fault with the ventilation. There was no fault. Somebody had spent two days chasing cable into a wall in the comms room with the doors wedged open.

The contract does not help you here. Under the rectification period the contractor is obliged to put right the defect. Nothing in a standard JCT form obliges him to clean up the aftermath of putting it right to the standard of a sparkle clean, and every contractor I know reads it that way. So the invoice lands on the occupier. Somebody is paying for it, and by then the fit-out account is closed, the project manager has moved to another job, and the cost falls into facilities revenue where nobody forecast it.

The dust that arrives three weeks after you move in

There is a second source that has nothing to do with snagging and everything to do with how Cat B floors are built. Raised access floor voids in London offices collect an astonishing volume of construction debris – offcuts, screws, cable ties, drill swarf, sandwich wrappers – and nobody cleans them because nobody lifts the panels once the carpet tiles are down. Then a data cabling change six weeks post-occupation lifts forty tiles across an open-plan area and every bit of that comes up with them.

If you are taking a floor with a deep void and any expectation of future cabling churn, void cleaning before the finishes go down is the cheapest money in the whole project. It costs a fraction of what it costs afterwards, when the work has to happen out of hours around furniture.

What should a tenant refuse to pay for?

A second sparkle clean, if the reason you need one is that the first was signed off too early.

This is where I talk people out of buying from me. If your snagging list is short – twenty items, no wet trades, no cutting – do not commission a formal post-snag clean at all. Get your day cleaners to spend two hours on a Friday with a microfibre and a decent vacuum, and spend the money on something else. A full clean on a 12,000 sq ft floor for the sake of some screwdriver dust round nine socket faceplates is a waste of your budget and I will say so on the phone.

The genuine test is whether wet trades or power tools came back. Plaster, paint, MDF cutting, core drilling, floor grinding – any of those and you need a proper clean with extraction, because that dust is abrasive and it will be walked into new vinyl and ground in permanently within a fortnight.

Retention, not a second contract

The better tool is the one you already hold. Retention on a Cat B typically runs at three per cent, released half at practical completion and half at the end of the rectification period. Make post-remedial cleaning an explicit condition of the second release, written into the contract before signature, and price it into the contractor’s obligations rather than buying it separately six weeks later at your own cost. Most contractors will accept the clause at tender stage. Almost none will volunteer it.

How should the three cleans be priced across a London Cat B?

By condition, not by floor area, whatever the per-square-foot rates in circulation suggest. A stripped-back warehouse conversion in Wapping with exposed services, sprayed soffits and polished concrete takes roughly twice the sparkle-clean hours of an equivalent area at Chiswick Park with grid ceilings and carpet tiles, because everything is up high and nothing hides. Glazed partitioning is the other multiplier – a floor with forty glazed meeting rooms is a glass job with some floors attached, and it should be priced by someone who has looked at the partition drawings rather than the net internal area.

Why the glass drawings matter more than the floor plan

Ask for the partition schedule before anyone quotes. Count the glazed doors and the acoustic sets, then work out how much of that glass sits over a stairwell where you need pole work rather than a squeegee off a hop-up. A West End floor I priced in Fitzrovia last spring had 310 linear metres of glazed partitioning across 9,000 sq ft, and the glass alone accounted for just under half the sparkle-clean labour. An equivalent area at Ruskin Square, mostly solid partitions, came in a third under. Net internal area told me nothing useful about either.

Get all three quoted as one package, from one contractor, at tender. The builder’s clean and the sparkle clean go into the contract sum where they belong. The snagging clean gets a provisional sum against it, with the trigger written down: wet trades or powered cutting after PC means it fires, and the money comes out of retention.

Nobody wants to have that conversation in week one. It is a lot cheaper than having it in week thirty-eight, on the phone, standing in a floor full of grey dust with a lease that started on Monday.