Overnight Kitchen Extract Cleaning: What to Expect

By the Duct Doctor team · Updated 30 October 2026

No kitchen wants to close for a day so the extract can be cleaned. That’s why most cleans happen out of hours: overnight after the last service, early in the morning or on the day you’re shut. Done well, the team arrives after you’ve gone, and you come back to a clean system and a kitchen ready to cook. This guide explains how an overnight clean usually works and what you need to sort out beforehand.

Before the night

Every clean starts with a survey, either from photos and details or on site. That tells the team how big the system is, where the access panels are, how to reach the fan and discharge, and roughly how long the work will take. Then you get a fixed quote and agree a date. See pre-clean surveys.

Before the night itself, agree:

the start time, after the last cooking has finished
the time the kitchen must be handed back
who will be on site, if anyone
parking, loading and access to the roof or plant areas

Keys, alarms and access

If nobody is staying on site, the team needs a way in and a way to secure the building afterwards. Common arrangements are:

a member of staff lets the team in and returns to lock up
a key holder or security team meets the team on arrival
keys and alarm codes are passed over in advance, then returned

Tell your alarm company or monitoring centre if contractors will be on site overnight. Check that fire alarm detectors in the kitchen won’t be set off by steam, and agree what happens if they are. In shared buildings, building security or the managing agent may need to know too.

Need it done? Duct Doctor cleans and tests kitchen extract and ventilation systems across London and the South East, with a certificate and photo report after every clean. Get a fixed quote.

During the clean

Cooking equipment is switched off and left to cool. The kitchen is sheeted to protect surfaces and equipment. Grease filters come out, and the canopy, plenum, ductwork, fan and discharge are cleaned through access panels, by hand scraping and with degreasers, hot water or steam, depending on the deposit. Grease readings and photos are taken before and after. Waste grease and water are contained and taken away.

If anything unexpected turns up, such as a damaged access panel, a damper that won’t reset or a fan that sounds wrong, the team records it with photos and lets you know. Small issues can often be put right on the night. Anything larger is quoted separately, so there are no surprises.

Ready for the morning

Before leaving, the team removes sheeting, refits filters and panels, checks the fan runs and leaves the kitchen clean and tidy. You should be able to switch on and start breakfast prep as normal. The TR19® certificate and photo report follow, showing what was cleaned, the readings and any areas that couldn’t be reached.

Tips for a smooth night

Clear worktops and put food away before the team arrives.
Let the team know about any equipment that mustn’t be moved.
Make sure roof access, ladders and hatches can be used safely.
Leave a phone number for someone who can answer questions during the night.
Check the kitchen first thing and raise anything straight away.

Duct Doctor works evenings, overnight and weekends across London and the South East, so kitchens don’t lose a service. If something goes wrong out of hours, there’s a 24/7 emergency callout too.

Quick answers

Will the kitchen be ready for breakfast?

That’s the aim of an overnight clean. Agree the hand-back time when you book.

Do we need to stay on site?

Not necessarily. Many sites hand over keys or arrange a key holder.

What if the system is too big for one night?

The survey will show this. Larger systems can be cleaned over several nights, section by section.

Related services

More advice

This guide is general information. It isn’t legal or insurance advice: check your own policy wording and lease, and speak to a qualified adviser about your fire risk assessment.