How to Check if a Contractor Is Legit

TL;DR (Too Long; Didn’t Read)

Before you hire, confirm your contractor’s credentials, insurance and guarantees to avoid cowboy builders and protect your investment. In the UK, legitimate contractors are usually registered with schemes like FENSA, CERTASS, or MCS, and they’ll provide an insurance-backed guarantee. Always verify business details via Companies House, ask for references, and avoid anyone demanding large upfront payments or refusing paperwork.

Why Checking Contractors in the UK Matters

Hiring a contractor isn’t just another household expense; it’s a major financial decision that affects the safety, value, and comfort of your home.

But every year UK homeowners are left dealing with unfinished work, botched jobs, or scams by rogue traders.

Choosing a contractor based on a slick website or pushy salesperson can be a costly mistake. A little due diligence at the start will save you thousands of pounds later and give you peace of mind that your property is in safe hands.

Step 1: Check Accreditations and Competent Person Schemes

One of the quickest ways to confirm if a contractor is legitimate is to check if they’re registered with the relevant UK competent person scheme or trade body.

• Windows & Doors - FENSA or CERTASS registered installers can self-certify work complies with Building Regulations.
  
  

• Renewables - MCS (Microgeneration Certification Scheme) accreditation is essential for solar panels, heat pumps and other renewable installations.
  
  

• Gas - Only Gas Safe registered engineers are legally allowed to carry out gas work. Always ask for their ID card.
  
  

• Electrical Work - Look for NICEIC, ELECSA, or NAPIT approved contractors to ensure compliance and safety.
  
  

No membership or proof? That’s your first red flag.

Step 2: Verify Contractor Insurance

Accidents and unexpected problems happen, even with experienced professionals. Reputable contractors will protect you (and themselves) with the right insurance.

At a minimum, they should carry:

• Public Liability Insurance – covers damage to your property or injury to others.
  
  

• Employer’s Liability Insurance – legally required if they employ staff.
  
  

• Contract Works Insurance – protects your project if it’s damaged, delayed, or left incomplete.
  
  

Always ask for certificates. A genuine contractor won’t hesitate to share proof.

Step 3: Ask for Insurance-Backed Guarantees

Standard guarantees aren’t much use if the business shuts down. That’s why an insurance-backed guarantee (IBG) is essential. It ensures your installation or building work remains protected even if the contractor ceases trading.

This is particularly important for high-value home improvements like double glazing, roofing, or renewable systems.

Step 4: Check Business Credentials

It only takes a few minutes online to confirm if a contractor is legitimate.

• Search Companies House to check their registration, directors, and status.
  
  

• Look for a VAT number - common for larger or established firms.
  
  

• Confirm they have a physical address, not just a mobile number or PO Box.
  
  

• Review their online presence. A professional website and active social media profiles show they’re established and accountable.
  
  

Step 5: Read Reviews and Ask for References

Online reviews can be revealing, if you know where to look. Platforms like Trustpilot, and Google Reviews can give you an idea of the contractor’s reputation.

Look for consistent patterns in feedback, not just star ratings. Are there repeated complaints about unfinished work? Do reviewers mention reliability and professionalism?

Don’t rely solely on online feedback. Ask the contractor for references, ideally from recent jobs. A trustworthy professional will happily put you in touch with past clients and may even invite you to view completed projects.

Step 6: Spot the Red Flags

Some warning signs are too big to ignore. Avoid contractors who:

• Demand large upfront deposits in cash.
  
  

• Refuse to provide a written contract or guarantee.
  
  

• Use high-pressure sales tactics to rush your decision.
  
  

• Have no online presence or verifiable business details.
  
  

If something feels “off”, trust your instincts as it’s usually for a reason.

Why It’s Worth Doing These Checks

Cutting corners with contractor checks may save you a few hours, but the risks are significant:

• Work that doesn’t comply with UK Building Regulations.
  
  

• Problems selling your home without proper certificates.
  
  

• Financial losses from unfinished or poor-quality work.
  
  

By contrast, accredited and insured contractors provide peace of mind, protect your investment, and help future-proof your property.

Your home is your biggest asset. Don’t hand it over to someone you haven’t vetted. By checking accreditations, insurance, guarantees, and references, you can filter out cowboy builders and hire with confidence.

The time you spend now will save you stress, money, and headaches in the future!