The first robot clean should be a controlled trial on one roof section, with before and after photos from the same angle, a defined pass sequence and a written client sign-off. In 2026, teams that do this keep the contract; teams that clean the whole roof on day one often lose it.
Why? Because the first clean sets expectations. If the client sees a streaked pane or a water spot they did not anticipate, trust drops before the machine has done anything wrong.
What belongs in the first-clean checklist?
- Pick one representative section, 200-400 m2, not the whole roof.
- Baseline photos from fixed vantage points, with a scale reference.
- Record the glass type, pitch and any known defects.
- Note water source, filtration and drain path.
- Agree the acceptance standard in writing before starting.
- Run the pass, then photograph the same vantage points.
Why does the acceptance standard matter so much?
Because clean is not a number. A client might expect spotless and get 95 percent clean, which for a glass roof is often a good result. Agree the standard up front: how many spots per square metre at handover, whether dried water marks count, and how long after cleaning the check happens. Without that, the first clean becomes a debate rather than a delivery.
What goes wrong on a first clean?
Three things recur. Hard water leaving mineral marks because nobody tested the supply, which is why we always carry a filter on the first job. Suction pauses at wet seal joints that leave a wet band, fixed by a slower second pass. And edge undercleaning near frames, because the operator was cautious about the drop. Each is easy to fix if you expect it; each looks like incompetence if you do not.
Another quiet one: a machine rated for a slope that, on the day, is wet and a bit steeper than the drawing said. If the pitch is marginal, tell the client before the trial, not after a slip. Our notes on commissioning a robot cover the pre-start checks.
How long should the trial take?
Half a day on site. Two hours of setup and one representative pass, then a walk-through with the client while the glass dries. Do not rush the walk-through; the wet look hides streaks, the dry look reveals them. If the client can see it dry and sign, you are done.
Who should be at the handover?
The operator who ran the machine, the person who will own the clean going forward, and the client’s sign-off contact. If the client sends a facilities manager who did not commission the clean, make sure the standard is written down, because verbal recollection will not survive staff turnover.
What happens after a good first clean?
You go to a fixed cycle, usually 6 weeks for a busy atrium and 10-12 weeks for a factory roof, and you keep the photo log going. The first clean is where you win or lose the relationship; the rest is repetition. If you want the sales side covered, the contact page is the place to line up a trial.
What should the written acceptance standard contain?
Three numbers and one rule. State how many spots per square metre count as clean, whether dried water marks are acceptable, and how soon after cleaning the inspection happens. The rule is the vantage point: agree where the client will stand and look, because glass looks very different from the roof edge than from the floor below.
Write it on one page with the client’s signature. A verbal agreement on a first clean evaporates the moment the person who agreed moves on, and glass roof contracts often outlive their original signatory.
How do you handle edge glass at the trial?
Edge panes near a frame or a drop are the hardest to clean and the most likely to be missed. On the trial, clean one edge run by robot and one by hand so the client can compare. If the machine leaves a 100 mm band the client dislikes, either budget a hand finish or set the standard to accept it. Better to resolve that on 300 m2 than across 5,000.
What about weather on the trial day?
Do not trial in rain. Wet glass hides the result and the client cannot see drying behaviour. Pick a dry day with light cloud so the sun is not glaring off a wet pane. If the forecast is marginal, move the trial; a rushed first clean on a bad day undoes weeks of groundwork.
How do you turn a good trial into repeat work?
After a clean sign-off, set the cycle in writing before you leave the site. Offer a 6-week or 12-week option, since most roofs fall between those two, and put the first three dates in the calendar there and then. A trial that ends without a booked next visit often fades, because the client moves on to the next task.
Then keep the photo log going every cycle. When renewal time comes, twelve months of dated photos make the decision easy and short.
Key Takeaways
- Trial one 200-400 m2 section, not the whole roof, on day one.
- Agree the acceptance standard in writing before the first pass.
- Filter hard water on the first job; mineral marks are the top complaint.
- Let the glass dry before sign-off so streaks show.
- Have the future owner of the clean present at handover.