Choosing the right builder for your home extension

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If you love your home but feel like you need more space, building an extension can be the perfect alternative to the stresses of moving house. As well as increasing your living space, the right extension can also add significant value to your home.

Given the scale and costs of an extension project, finding the right extension specialist is key to ensuring a successful build. We spoke to some of the experienced tradespeople recommended on MyBuilder to find out the key things you should know in order to make the right choice:

  • Find out if they’ve done similar extensions to yours
  • Make sure you are comfortable with them
  • Look out for experience as much as accreditations
  • Get like-for-like quotes and make sure everything is included
  • Establish a payment plan
  • Check their familiarity with planning permission and local regulations
  • Agree what aftercare will happen after the build

Keeping these points in mind can help you focus on what to look for when you’re meeting with tradespeople and getting quotes for the work. Carry on reading for more details on how to go about finding the right tradesperson for your job.

Find out if they’ve done similar extensions to yours

Extensions are far from a simple, off-the-peg purchase. Extensions come in all shapes and sizes, and are as different as the homes they are added to, whether you’re adding a new room such as an orangery, creating a large kitchen-diner, or even a two-storey extension that adds both downstairs living space and another bedroom upstairs.

When looking for an extension builder for your extension project, it’s sensible to speak to ones who have performed similar builds to the one you have planned. As well as seeing previous examples of their work that they can show you as part of their portfolio, you can arrange through the builder to visit their previous jobs - they should be happy to put you in touch with previous clients they have done work for before.

Vasile Ghinda of V Ghinda Builders specialises in extension building in south-east London, and has dozens of pieces of positive feedback for his work on MyBuilder. For him, getting people to see his previous work is essential to fostering trust with new clients:

I always take new customers to see my previous work where I can. I’ll convince them to come with me - I’m passionate about doing it. I just think it helps make prospective clients confident that they can trust in my work. I’d feel uneasy about anyone who isn’t willing to show off their previous work - if they’re proud of it, they should be willing to show it off.

Vasile Ghinda, V Ghinda Builders


Lewis Sage of UPS Home Improvements in Romford has more than 150 pieces of positive feedback on MyBuilder. He specialises in home renovations and extensions. He told us:

Any good builder who takes pride in their work should be happy to put you in touch with old clients. When I’ve done a good job and the client is happy with it, I’ll say to them, can I ask a favour, can I use you for a reference in future, and it’s no trouble. I’d say to clients get out there and have a look at something the tradesperson has done in your local area - there’s nothing better than actually seeing it. The other good thing to do is ask if they have a build currently on the go, and go along and see that. That way, you don’t just see a nice, tidy job, you can make sure everything behind the scenes is being done properly.

Lewis Sage, UPS Home Improvements

Make sure you are comfortable with them

As well as finding out if they are familiar with your kind of job, you should simply assess how comfortable you feel with the potential tradespeople. You can do that from your first contact with them; are they polite on the phone, do they arrive for meetings at the scheduled time, do they ask lots of questions about the project?

Extensions aren’t built in a day, and the entire process can last for several months - being able to maintain good communication throughout the build is essential. You’re not looking to become best friends with them, but you should be able to have a professional relationship - you must feel comfortable speaking openly about any concerns that may arise, and dealing with any issues. Vasile said:

The first thing I’d expect someone to ask about is experience, how long you have worked, what jobs you have done that are the same. But you also want to know what they are like. You need to be able to talk to them, get on with on them.

Vasile Ghinda, V Ghinda Builders


Paul Coulson of KDBS in Newcastle regularly takes on extension projects, and has racked up more than 350 pieces of positive feedback on MyBuilder. He said:

Getting on with a tradesperson is really important for a homeowner. If you’re going to be in their home for weeks at a time, you have to get on with them. All it takes is one miscommunication for things to turn sour, and the whole job can be an issue. If you can sit down together and have a proper chat, then everything will go more smoothly.

Paul Coulson, KDBS

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If you do feel comfortable, you can start to consider how qualified they are for the project.

Look out for experience as much as accreditations

As well as seeing previous work from builders, there are other things you can do to assess their experience. On MyBuilder, you can read honest feedback on the jobs they have undertaken for homeowners, as well as seeing pictures of the jobs they have taken on. Don’t be afraid to ask them questions as well, about any qualifications they may have, their length of time in the business, or how they’ll approach your own particular job. Be wary of tradesperson who seem to overpromise. As Vasile says:

I’d be wary of anyone who tells you that the job will be done in a suspiciously short amount of time, or will happen exactly as planned with no hitches. I’ve been doing this for a while, and I know that every big job has issues come up, and delays can be unavoidable. All you can promise is that you will be reliable and thorough, and work to overcome any issues.

Vasile Ghinda, V Ghinda Builders

You can also find out if the tradesperson is a member of any trade associations or accreditation schemes. Builders who work on extensions may belong to a variety of organisations. Some you may encounter include:

  • Federation of Master Builders (FMB): The UK’s largest trade association for the construction industry, all members are inspected by the body and expected to uphold standards and follow a code of conduct. There are different levels of membership, with the highest, Build Assure, offering the option of an insurance-backed building work guarantee.
  • Guild of Builders and Contractors: Members of this body who become a “Trusted Member” have to demonstrate three years of trading with customer and financial referees, and abide by certains standards such as providing written contracts and clear payment plans.
  • Guild of Master Craftsmen: Covering a variety of trades, each full member is assessed in person by the Guild to ensure they are reaching high standards of work. The Guild also provides a conciliation service for disputes between homeowners and member tradespeople.
  • National Federation of Builders: Members must provide business and financial references, have public liability insurance and adhere to a code of conduct. Although it does not offer a guarantee against work, it operates a complaint procedure.
  • FairTrades Association: Established in 1983, the FairTrades Association covers multiple trades and works to ensure standards, encouraging its members to offer insurance-backed guarantees on their work. 

Membership of a body such as this is a good indication that a tradesperson is competent and working up to certain standards, however, there are many experienced tradespeople who do not belong to these bodies - there is no obligation to be signed up, unlike membership of the Gas Safe Register, a legal requirement for tradespeople who work with gas in the home. Use your own judgement to assess a tradesperson’s experience, and see accreditation as a healthy recommendation or extra seal of approval. Vasile says:

People trust accreditations because they show that a tradesperson has made an effort to present themselves well and show off their quality. On bigger jobs like extensions, it does make sense to check for these, because you want every reassurance you can get.

Vasile Ghinda, V Ghinda Builders

Paul added:

There are some membership bodies which offer practical benefits to homeowners who hire their tradespeople, such as offering an insurance-backed guarantee, so some people like the peace of mind that brings. Others are good for tradespeople when it comes to things like advertising their business or finding leads, so are less important for homeowners. If I was a homeowner looking for a tradesperson, it’s the experience I’d look for over any particular memberships.

Paul Coulson, KDBS


Get like-for-like quotes and make sure everything is included

It’s advisable to meet with, and get quotations from at least three tradespeople. The detail and scope of their quotation can tell you a lot about their process. It’s important to make sure that all the quotations contain the same elements - do they include materials and labour, as well as any subcontracting the tradesperson may do, and VAT? The only way to accurately compare quotations is if you are comparing like-for-like.

Taking a sample of at least three quotations can help you spot any that seem unreasonably low - if this is the case, it could be the sign of a tradesperson who wants to win the job, but will make up the true value by adding on extra costs during the course of the build. Similarly, a short “back of an envelope” quote won’t tell you enough to make a good judgement - it should be complete and thorough. 

While the build is in process, you may find that you want to make changes that go beyond the remit of the work laid out in the quotation. Find out how the tradesperson might deal with this if it occurs. Vasile said:

It’s fairly commonplace for things to crop up that don’t originally appear in the quotation. People have brainwaves about something extra they want, or something they want changing. Because I’m experienced, I have a long list of extras that I commonly see, so I can be straightforward about any additional charges that will be added on. It helps both parties to be upfront and open about costs.

Vasile Ghinda, V Ghinda Builders

Establish a payment plan

After agreeing to a price through an accurate, written quotation, make sure you have a payment plan in place that you are comfortable with.

A reputable tradesperson will generally not expect, or ask for, the total value of an expensive extension job upfront. However, a small deposit is not uncommon. While many builders buy materials on account from trade suppliers, and will not request money up front to cover these costs, if it’s a small firm working on a large build with high costs involved, this may be worked into the plan.

Some builders may defer payment until after the build is completed, but the most common method of payment is an installment plan that sees you paying certain percentages of the total bill after various stages of the job are completed. Stages may typically include after the groundwork has been completed, or before the roof is added. Your local authority’s Building Control department should inspect various stages of the project and sign them off, which can make natural payment points. Other tradespeople may prefer to be paid on either a monthly or weekly basis, especially over a longer timeframe, in order to cover their material costs and paying subcontractors and employees.

It’s also common to arrange a retention payment - a sum of money (typically between about 2% and 5% of the overall cost of the build), which you as the homeowner keep until final sign-off by Building Control on the project, or for a period afterwards, to ensure the tradesperson finishes the job to standard and is happy to come back to deal with any snags. Lewis said:

My policy is to leave 5% of the total cost with the client until after all the snags are dealt with. There will always be something - and it’s the homeowner’s prerogative to find any issues and flag them up - they should hold us to account. Even the best tradesperson in the world can miss something. So I let them live with it for a bit, and draw up a list of any issues - skirting unfinished, issues with the paint, whatever. Then I come back and they walk me round, and we talk them all through, and see what I have to finish. When that’s done, I’ll take the final payment.

Lewis Sage, UPS Home Improvements

Vasile added:

I like to sit down with clients and make a schedule with them, with the timetable of what the build should be like, and a payment schedule to go with it. I like to have the first payment after the foundations are in place. Having it established in advance means it’s fair for the tradesperson and the client - everyone knows what to expect. I leave a 2% retention with the client, so they know I’ll stay involved with the job all the way through. I only collect the final payment after the final building control approval.

Vasile Ghinda, V Ghinda Builders

Check their familiarity with planning permission and building regulations

Many houses will have permitted development rights when it comes to extensions, meaning that you will not need to apply for planning permission when going ahead with the build. There are exceptions to this however, mostly related to the size of the extension in relation to the existing house and your remaining land, and how close it comes to your property boundaries. Additionally, if your home is within a location such as a conservation area, or is a listed property, you may have to obtain planning permission before your work can go ahead.

Making sure that any tradesperson you hire is familiar with planning laws, as well as building regulations and their requirements, can help jobs go a lot more smoothly. Experienced builders will be knowledgeable about all the latest requirements and how they apply to your project, and how they will be dealt with by the planning departments of local authorities - they may even know planning officers to ask for advice. Beware of any tradesperson who is casual about the need for planning permission or building control inspections - breaching regulations can lead to costly fines, and being forced to undo any work.

There are two separate sets of requirements your build may have to abide by - planning permission and building regulations. Planning permission, dealt with by a local authority’s planning office, deals with the development of buildings and its impact on the wider community, for example, how an extension effects the street scene, or if an office block can be converted into flats. Building regulations, dealt with by a building control department, sets standards for the design and build quality of any development, ensuring the health and safety of those who will use the building, as well as providing standards on energy efficiency and requirements like disabled access.

Regardless of whether or not you need planning permission, you will need Building Control to sign off the work as it happens, with inspectors coming to monitor the progress of the build and ensure it is being done in line with legal regulations. Lewis emphasised the importance of hiring someone familiar how the process works:


I’m very familiar with local planning offices and all the Building Control staff. When they come on site, they say hello and shake my hand, because they know I do a good job. The whole process is easier with that experience.

Lewis Sage, UPS Home Improvements

Some homeowners hire a tradesperson for their project before they have plans in place and have established whether or not they need planning permission. Many tradespeople can help put clients in touch with architects and structural engineers who can create the plans necessary for submission. Others homeowners will have their plans in place before hiring a builder to fulfill them. Often, builders will want to see plans and drawings before being able to offer an estimate. Vasile said:

I prefer to come in when the plans are already in place - I can look at the drawings, see what needs to be done, and get to work as soon as possible. But I’m happy to be hired beforehand as well. I know good architects and people I can suggest for work, just like I know good electricians, so we can help the project get off the ground from the very beginning.

Vasile Ghinda, V Ghinda Builders


Agree what aftercare will happen after the build

With a big project like an extension, there is a high chance that there will be complications along the way. These issues may not manifest themselves until after the work is notionally complete, and the tradesperson has moved on to other jobs. That being so, it is sensible to hire a tradesperson who is happy to return to the build to follow-up on their work and make right anything that may have happened since the work finished.

Some builders will put something to this effect in their initial contracts with the homeowners, while others will offer a more informal arrangement. Vasile said:

I like to put it in the contract with them, just to give them peace of mind. I will generally come back after one month, to make sure everything is as it should be, then sometimes after six months as well to check in. Usually I can sort out small issues without payment, though it depends on what happens.

Vasile Ghinda, V Ghinda Builders

See if any tradesperson you are considering hiring is willing to offer an option like this. If the tradesperson is willing to put you in touch with previous clients to see their work, then it is a good sign that they have maintained good relationships, taken pride in their work, and ensured that they have followed-up on any issues that have arisen.

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