How to Check a Builder’s Previous Work
Reviews tell you what people thought. Previous work shows you what the contractor actually does. Here is how to look at it properly.
Evidence over description
Anyone can describe their work well. Seeing it, and hearing from the people who paid for it, tells you far more.
Reviews, online profiles and a good conversation on the doorstep all tell you something about a contractor. Previous work tells you something different: what they actually produced, for someone like you, on a job like yours.
Checking it does not need technical knowledge. You are looking for evidence that the contractor has done similar work, that it was finished, that it has lasted, and that the customer would use them again.
This guide covers the ways to see a contractor's previous work, what to ask their past customers and how to judge what you see. It is one step in the wider process set out in how to vet a builder, and in our guide to choosing and checking a building contractor.
Why it matters
What previous work can tell you that reviews can't
Online reviews are useful, but they are usually written soon after a job ends and they tend to focus on how the customer felt: whether the team was polite, tidy and on time. That matters. It does not always tell you whether the work was done to a good standard or how it has held up.
Previous work fills that gap. A roof that is still watertight several winters later, an extension that the owner is still pleased with, a customer who would happily have the same firm back: these are strong signals, and they are hard to fake.
It also tells you whether the contractor's experience matches your job. A builder with years of experience in kitchens may be very good, but if you need a loft conversion, what you want to see is loft conversions. Our guide to how to read builder reviews covers the review side in more depth.
Where to look
Six ways to see a contractor's previous work
You don't need all six. Two or three, used together, usually give a clear picture.
Photographs of recent jobs
Ask for photos of jobs similar to yours, ideally showing before, during and after. Ask where and when each one was done, and what the job involved.
Finished work you can see from the street
For external work such as roofs, fronts and extensions, a contractor may be able to give you addresses of finished jobs you can look at from the pavement, with the owner's agreement.
A conversation with a past customer
The most useful check of all. A short phone call with someone who had similar work done tells you about the result and about the experience of getting there.
A visit to a finished job
For larger projects, some past customers are willing to show their work. This is a favour, so it has to be arranged through the contractor.
A job in progress
Seeing a live site, with permission, shows you how the contractor runs a job day to day: how tidy it is, how materials are stored and how the team works.
Reviews that name the work
Reviews that describe the specific job, include photos or mention how the work held up months later are more useful than a line of general praise.
Photographs
Getting real value from photos
Photos are the easiest thing for a contractor to share and the easiest to take at face value. A few simple questions make them much more useful.
Ask about specific pictures. Pick two or three and ask where the job was, when it was done, what the problem was and what they did. A contractor who did the work will answer without hesitation and usually with detail.
Ask for the whole sequence. A single "after" shot shows the finish. Photos taken before and during the work show what was actually involved and how the job was approached.
Look for consistency. Do the photos look like they come from the same business: similar vans, similar signage on site, similar kinds of work? A portfolio that jumps between very different styles and trades is worth asking about.
Match them to your job. Ask for photos of work that resembles yours in type and size. A good selection of small repairs does not tell you much about a full replacement, and the reverse is also true.
Talking to past customers
What to ask someone who has used them
Keep it short and polite. They are doing you a favour. Two areas are worth covering.
About the work
- What did they do for you, and when?
- Was the finished work what you expected?
- Has anything needed attention since?
- If it did, how did they handle it?
- Did the job need building control sign-off, and was it provided?
About the experience
- Did they start and finish when they said they would?
- Did the final price match the quotation?
- Were they easy to get hold of during the job?
- Did they leave the site tidy?
- Would you use them again?
"Would you use them again?" often tells you more than everything else put together. Listen to how it is answered as well as what is said. A quick, warm yes is different from a pause followed by "probably".
Seeing it in person
Looking at a finished job
You are not inspecting someone's house. You are getting a general sense of the result, and of whether the owner is pleased with it.
Arrange it through the contractor
Never approach a past customer's home uninvited. Ask the contractor to arrange it, and accept that some people will prefer not to.
Go with a few questions
Use the list above. Keep the visit short and let the owner lead.
Look at the whole result
Notice whether the work looks finished and neat, whether the surrounding area was left in good order and whether the new work sits well with the rest of the house.
Ask how it has held up
Older work is often more informative than recent work. Something finished a few years ago that still looks right and has caused no trouble is strong evidence.
Judging relevance
Is the work you've seen relevant to your job?
Good previous work is encouraging, but check that it actually speaks to your project. Four questions help.
Is it the same kind of work? Trade matters. So does the type of job within a trade: repair versus replacement, a single rooflight versus a full extension.
Is it a similar scale? Running a six-week build takes different skills from a one-day repair. If your job is larger than anything they have shown you, ask about the largest similar job they have completed.
Is it recent? A strong job from many years ago is less useful if the business has changed hands or the team has changed since. Ask whether the same people will work on yours.
Was it their own team? If parts of a job were done by other firms the contractor brought in, ask whether the same firms would work on your job. This is common and not a problem, as long as you know. Taking up references is covered in more detail in taking up references.
When there's less to see
Reasonable explanations, and what to ask instead
Not every good contractor has a polished portfolio. A lack of previous work to show is worth understanding, not an automatic reason to walk away.
Customers value their privacy
Some past customers prefer not to be contacted or visited. That is fair. Ask for photos and written references instead, and ask whether one or two customers could take a short call.
The business is new
A newly formed business may have an experienced person behind it. Ask about their work history before the business started and whether they can show work from that time.
They cannot show anything at all
An established contractor with no photos, no references and no addresses is unusual. Ask why, and weigh the answer alongside everything else you know about them.
Timing
When to ask, and how
Asking at the right moment makes it a normal part of the process rather than an awkward request.
Mention it when you first get in touch
Say early on that you would like to see examples of similar work. It sets expectations, and a contractor can bring photos to the visit.
Look at examples during the site visit
Ask to see photos of comparable jobs and ask about two or three of them. The guide to questions to ask at a site visit covers what else to raise while they are there.
Ask for a reference or an address before you accept
Once you have a quotation you are seriously considering, ask for one or two past customers you could speak to, or an address you could look at from the street.
Make the call before paying anything
Speak to the past customer before you pay a deposit. If something they say gives you pause, you can raise it with the contractor while nothing is committed.
The bigger picture
Previous work is one check among several
Good previous work is persuasive, and it should be. It is still only one part of the picture, and it answers a particular question: can this contractor do this kind of job well?
It does not tell you whether they are insured today, whether the business is what it says it is, or whether the terms in their quotation are clear. Those need separate checks. Ask for a current insurance certificate and read it, as described in checking a builder's insurance. If the business is a limited company, look it up on Companies House, which is free; checking a company on Companies House explains what the record shows.
Equally, a lack of polished photos does not cancel out strong references, a clear written quotation and a contractor who answers every question directly. Weigh everything together. The contractor checking checklist puts all the checks in one place, in a sensible order.
When we coordinate the work
Work history is one of our checks
Every contractor in Mortaro's network was checked for trade experience and prior work history before being introduced to any customer, along with public liability insurance, reviews and references, the warranties they provide, and their ability to meet our standards.
That is a starting point, not a substitute for your own view. If you would like to know more about your contractor's previous work before you commit, ask us and we will raise it with them. Your contractor is named in your quotation, so you can also look them up yourself. Our contractor network explains how contractors are checked and what happens if they fall short.
Straight answers
Questions about checking previous work
Is it rude to ask a builder for examples of previous work?
No. It is a normal request, and established contractors are used to it. Most are pleased to show work they are proud of.
How many past customers should I speak to?
One or two conversations with customers who had similar work done are usually enough to give you a clear picture. Quality of conversation matters more than number.
Can I see a roofer's previous work if it is on other people's houses?
Often, yes, from the street and with the owner's agreement. Ask the roofer for addresses of recent similar jobs. Our answer on seeing a roofer's previous work covers this.
What if a past customer had a problem?
Ask how the contractor dealt with it. Problems happen on building jobs. A contractor who came back promptly and put it right may be a better choice than one with an unblemished but thin record.
Start here
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