What Is a Main Contractor?
The business you contract with to carry out the building work and take overall charge of it, whether they do every part themselves or bring in other trades.
The short answer
The firm you contract with to carry out and take charge of the building work.
A main contractor is the business that agrees with you to carry out the building work and takes overall responsibility for it. They may do everything with their own team or bring in other trades for parts of the job, but either way they run the work on site and answer to you for it. Your contract for the work is with them.
On a small job such as a roof repair, the main contractor might be one tradesperson doing it all. On an extension, it's usually a building firm that organises bricklayers, roofers, electricians and plasterers under a single contract with you. The label describes the role, not the size of the business.
The role
What a main contractor typically does
The detail depends on the contract, but the shape of the role is fairly consistent.
Prices the work
Visits the property, works out what the job involves and gives you a quote or contract price for it.
Carries out the work
With their own people, other trades they bring in, or both. The standard of all of it is theirs to answer for.
Runs the job on site
Plans the order of work, orders materials, books other trades and keeps the programme moving day to day.
Holds insurance
A main contractor would normally carry public liability insurance for the work they do at your property.
Looks after safety on site
Planning and managing health and safety during the work falls to the contractor in charge of it.
Puts defects right
If the work turns out to be faulty, you take it up with the main contractor, under their warranty and your contract.
Two ways to run a job
One main contractor, or several trades hired separately
Some homeowners hire each trade themselves. It can work, but it moves the organising onto you.
With a main contractor
- One contract for the whole job
- One party responsible for the work
- They sequence and coordinate the trades
- Handovers between trades are their problem
- Less of your time spent organising
Hiring trades separately
- A separate agreement with each trade
- Each is responsible only for their own part
- You sequence and coordinate them
- Gaps between trades can fall to you
- Can save money, at a cost in your time
Related terms
Main contractor, subcontractor and principal contractor
You'll often see a few similar words used around building work. A subcontractor is a trade the main contractor brings in to do part of the job. Your contract isn't with them, which is why the main contractor normally answers to you for their work. Our answer on who is responsible for a builder's subcontractors explains how that plays out.
Principal contractor is a legal term from the Construction (Design and Management) Regulations 2015. Where more than one contractor works on a project, one is appointed to plan and coordinate health and safety during construction. On domestic projects, the client's duties under those regulations normally pass to the contractor, or to the principal contractor where there is more than one. The Health and Safety Executive's website sets out the detail. This is general information, not legal advice.
A main contractor is also different from an architect, surveyor or project manager, who may design or oversee a larger project on your behalf but don't carry out the building work themselves.
Why it matters to you
Knowing who your main contractor is
Before work starts, you should know exactly which business is your main contractor: its full name, whether it's a sole trader or a limited company, and how to reach it. That's the business your quote or contract should be with, whose insurance you should see, and who gives the warranty.
Check the name is the same everywhere it appears: on the quote, the insurance certificate, any company record and the bank details you're asked to pay. If it's a limited company, you can look it up free on the public register; our answer on checking a builder on Companies House shows how. Where a third party handles payments on the contractor's behalf, the paperwork should say so plainly.
It matters most when something needs putting right, because that's who you'll be asking. Our knowledge guide on what a main contractor is responsible for goes further into the detail, and the time cost of doing it yourself looks honestly at what coordinating separate trades involves.
Where Mortaro fits
Your main contractor, named before you commit
When we coordinate a job, the contractor we appoint from our network is your main contractor. They're named in your quotation before you commit. They carry out the work, hold the insurance and provide the workmanship warranty, and your construction contract is with them.
Mortaro coordinates everything around them: the site visit, the written quotation, communication, start dates and payment administration. We aren't the main contractor and we don't carry out any of the work. Who you're dealing with lays the arrangement out in a minute's reading.
Straight answers
Questions about main contractors
Is a main contractor just another word for a builder?
Often it's the same business. "Builder" describes the trade; "main contractor" describes the role of being the one you contract with and who takes charge of the work.
Does a small job need a main contractor?
Whoever you contract with for a single-trade job is in effect your main contractor. What you probably don't need is anyone above them. See do I need a project manager for a small job?
Can a sole trader be a main contractor?
Yes. The role doesn't depend on the size of the business. Our guide to sole traders and limited companies explains the practical differences.
Start here
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