How to Choose a Commercial Cleaning Contractor in London

Reviewed by the Crystal Facilities Management commercial team · Updated 2026

Choosing a cleaning contractor looks simple until you’re holding three quotes that all say something different. The cheapest isn’t the safest, the biggest isn’t always the best, and the wrong choice shows up as no-shows, complaints and a search for a replacement six months later. This guide gives you a clear, practical framework for choosing a commercial cleaning provider in London that actually lasts.

The seven things that actually matter

1. Transparent, sustainable pricing

A good contractor shows you how the price is built — hourly or per-visit, what’s included, and whether materials and consumables are extra. A rate that sits noticeably below a provider’s published “from” figure is a warning sign, not a bargain: it usually means an underpaid cleaner, thin insurance, or extras that appear on later invoices. Ask for an itemised quote, not a single headline figure.

2. Certifications and accreditations

Certifications tell you a provider is audited by someone other than themselves. Look for BICSc (British Institute of Cleaning Science) membership, SafeContractor or CHAS accreditation, ISO 9001 (quality) and ISO 14001 (environmental) where relevant, and CSCS/SSSTS-carded staff for site work. For catering environments, TR19-compliant kitchen and extract cleaning matters.

3. Proper insurance

Confirm public liability and employer’s liability cover, and ask for the figure. A serious commercial provider carries substantial cover — Crystal, for example, holds £10m insurance. Ask to see the certificate; a reputable contractor will send it without hesitation.

4. Directly employed, supervised, vetted staff

Ask who actually cleans your building. Directly employed, DBS-checked and trained staff under active supervision deliver far more consistent standards than a rotating cast of subcontracted casual labour. Ask how the team is supervised, how quality is checked, and what happens when someone is off sick.

5. A clear contract and accountability

You want a written specification (what’s cleaned, how often, to what standard), a named single point of contact, a defined process for missed cleans or complaints, and a fair notice period. Vague terms are where disputes live.

6. Reliability and cover

Cleaning only works if it happens every time. Ask how the provider guarantees cover for holidays and sickness, whether they offer same-day or out-of-hours response, and how quickly they react to an urgent request. In London, 24/7 availability is a genuine differentiator.

7. Verifiable reputation

Look past the testimonials on the website. Check independent reviews (Google, Trustpilot), ask for references from clients in a similar sector, and see whether the provider has a real, traceable track record rather than a brand-new page with five perfect reviews.

Red flags to walk away from

• A quote well below the London market floor with no explanation of how it’s sustainable.
• Reluctance to provide insurance certificates or proof of certification.
• No written specification — just a price and a handshake.
• Heavy use of subcontracted labour with no clear supervision.
• Pressure to sign a long contract immediately, with no free site survey.
• Only anonymous testimonials and no independently verifiable reviews.

Questions to ask before you sign

• Is your rate a clear, published “from” figure, and what does it include?
• What certifications and insurance do you hold — can I see them?
• Are your cleaners directly employed, vetted and supervised?
• How do you guarantee cover for sickness and holidays?
• Who is my single point of contact, and how are complaints handled?
• Can you provide references from clients in my sector?

Frequently asked questions

What’s the most important factor when choosing a cleaning contractor?

No single factor — but the most common reason contracts fail is choosing on price alone. A fair, sustainable rate combined with proper certification, insurance, directly employed staff and a clear contract is what delivers consistent standards over time.

What certifications should a commercial cleaning company have?

Look for BICSc membership, SafeContractor or CHAS accreditation, and ISO 9001/14001 where relevant. Site work should use CSCS/SSSTS-carded staff, and catering environments need TR19-compliant kitchen and extract cleaning. Always confirm public and employer’s liability insurance.

Why are the cheapest quotes risky?

In London, a rate that sits well below a provider’s published “from” figure rarely covers a fair wage, insurance, equipment and supervision at once. The saving usually reappears as high staff turnover, missed cleans, poor standards, or extras on later invoices — costing more than a fair rate would have.

Should cleaners be directly employed or subcontracted?

Directly employed, vetted and supervised staff give far more consistent results than rotating subcontracted labour. Ask who actually cleans your building, how they’re supervised, and how cover is arranged for holidays and sickness.

How do I check a contractor’s reputation?

Go beyond the website testimonials. Check independent reviews on Google and Trustpilot, ask for references from clients in a similar sector, and look for a real, traceable track record rather than a brand-new profile with a handful of perfect reviews.