Start With Basics: Is the Company Real?
Before you go any further, verify that the company you are dealing with actually exists as a legal entity. This is a basic step that many homeowners skip — but it matters.
- Search for the company name on Companies House (gov.uk/get-information-about-a-company). A registered limited company will appear with a registered number, registered address and filing history.
- Look for a physical registered address — not just a mobile number and a Gmail address. PO boxes are a warning sign.
- Confirm they have a working phone number and professional email address. If contact is only through WhatsApp or social media, be cautious.
- Check whether the company has been trading for a meaningful period. A company registered last month with no track record represents significant risk.
Check Their Insurance
Insurance is not optional — it is the difference between a recoverable problem and a financial catastrophe. You need to understand what cover your builder carries before they start work. There are three main policies you should ask about.
Public Liability Insurance
This covers damage to your property or injury to members of the public caused by the builder's activities. For domestic residential projects, a minimum of £1m is common, but £2m–£5m is more typical for larger projects. Ask to see the certificate — the date, limit of indemnity and policy number should all be visible.
Employer's Liability Insurance
If the builder employs staff or uses subcontractors, employer's liability insurance is a legal requirement in the UK. It covers claims from workers injured during the project. If your builder has anyone working on your site other than themselves, they must hold this cover. Again, ask for the certificate.
Contract Works / All-Risk Insurance
This covers the works, materials and site against damage — fire, flood, theft, accidental damage — while the project is under construction. Not all builders carry this as standard. Without it, if your partly-built extension burns down, the cost of rebuilding it may not be covered by anyone's policy. Ask specifically whether contract works insurance is in place for your project.
Important
Always ask for the actual insurance certificates — not just a verbal confirmation or a number quoted over the phone. A reputable, properly insured contractor will have no hesitation in providing this documentation.
Check Their Track Record
Insurance and company registration tell you a builder is legitimate. Track record tells you whether they are competent and reliable. Here is how to verify it properly.
- Check Google Reviews — look for consistent patterns rather than individual outliers. Recent reviews matter more than old ones. Read the negative reviews too, and see how (or whether) the company responds.
- Check Checkatrade or TrustATrader if the company is listed. Look at review dates and whether the work described matches the type of project you are planning.
- Ask for references from recent, similar projects. "Recent" means within the last 12–24 months. "Similar" means comparable in scope, value and type — a builder who has done 20 kitchen refits may not be the right choice for a complex structural extension.
- If possible, visit a completed project. This is the most reliable way to assess workmanship. Many builders will facilitate this if you ask — if they refuse, ask yourself why.
Watch for Warning Signs
Some patterns are strongly associated with poor outcomes. If you encounter several of these, treat them as genuine red flags — not minor concerns.
Get Multiple Quotes — But Compare Properly
Getting multiple quotes is standard practice and sensible — but it only works if you are comparing like with like. A quote for £60,000 and a quote for £45,000 on the same project are only comparable if they cover exactly the same scope, specification, materials and exclusions.
The most common trap: the lower quote is lower because it excludes items the higher quote includes — scaffolding, Building Control fees, waste disposal, structural calculations, provisional allowances for unknowns. When those items are added back in, the “cheap” quote may be more expensive.
Request itemised, written quotes from each contractor. Ask each one: what is not included? What assumptions have you made? What could cause the cost to increase? Compare the answers as carefully as you compare the numbers.
Ask These Questions Before Appointing
Before signing anything or paying any money, get clear answers to these ten questions. A good contractor will answer them without hesitation. Evasive or vague answers are informative in themselves.
Who will be on site every day, and how do I contact them?
Are you acting as the principal contractor for this project?
What insurance do you carry, and can I see the certificates?
Who is responsible for notifying Building Control and managing inspections?
Who manages the subcontractors — you or me?
How are variations to the scope handled and agreed?
What is the payment schedule, and what does each stage relate to?
What documentation will I receive at project completion?
Have you completed projects similar to mine recently?
Can I speak to a recent client?
What a Good Quote Should Include
A professional, reliable contractor produces a quote that reads like a document — not a text message or a number on a piece of paper. Here is what a properly prepared quote should include.
- Detailed scope of works (not a vague lump sum)
- Specification of materials, finishes and products
- Clear list of exclusions (what is NOT included)
- Stated assumptions (what the price is based on)
- VAT position — is VAT included or excluded?
- Programme — proposed start date, duration, milestones
- Payment schedule linked to defined stages of progress
- Variation process — how changes are agreed and priced
- Building Control and compliance route (who handles it)
- What documentation is included at handover
If a quote does not include these elements, you can and should ask for them. If the contractor refuses or says they are unnecessary, that tells you something important about how they run projects.