Terms and conditions for a loft conversion and extension builder

A loft conversion or extension is one of the largest purchases a homeowner makes from a trade, and the work takes place while they are living in the house. The terms need to deal with steels, provisional sums, party wall delays, building control sign-off and a final payment that falls due months after the deposit. I draft those terms for a fixed fee of £995, delivered in five working days.

Who this is for

Loft conversion specialists, extension builders and design and build contractors in England and Wales, trading as a sole trader, a partnership or a limited company. Most of your customers are homeowners and are consumers in law. Some work comes from developers, landlords and letting agents, who are business customers with different rules on payment and liability. One set of terms should handle both.

What matters in a loft and extension builder's terms

Drawings, design responsibility and permissions

Most loft and extension work is built to somebody else's drawings: an architect's plans and a structural engineer's calculations for the steels. Your terms should say plainly whether you are pricing a build only contract or taking design responsibility, because those are different risks and usually different insurance. They should also put planning permission, confirmation of permitted development under the Town and Country Planning (General Permitted Development) (England) Order 2015 and the accuracy of the drawings on the customer, and set out what happens when the drawings and the existing building disagree, which on older properties they often do.

Provisional sums and what opening up reveals

A price for a loft is built on assumptions about what sits behind the plaster. Undersized foundations, rotten wall plates, a chimney breast someone removed without support, textured coatings that may contain asbestos and fall under the Control of Asbestos Regulations 2012, wiring that will not pass inspection: none of that is visible when you quote. The terms need a mechanism that names your assumptions, prices provisional sums as provisional, and requires any extra to be agreed in writing, with its effect on the programme, before you carry on. Verbal agreements made on site are the usual source of disputes over the final invoice.

Deposits, cancellation and the fourteen day period

These contracts are usually signed at the customer's kitchen table or agreed by email, which brings them within the Consumer Contracts (Information, Cancellation and Additional Charges) Regulations 2013. A homeowner has fourteen days to cancel. On a job where you order steels and book scaffolding in the first week, that matters: if you start inside the period without the customer's express request you may not be paid for the work, and missing cancellation information can extend the period by up to 12 months. Your terms and your ordering process have to work together.

Stage payments, retention and the final invoice

Price the job in stages tied to events you control: deposit on order, payment when the steels are in, when the structure is watertight, at plaster, and the balance on completion. Say what triggers each stage and how long the customer has to pay. Homeowners often ask to hold money back until the completion certificate arrives; if you agree, fix the sum and fix the release date. For developers and other business customers the Late Payment of Commercial Debts (Interest) Act 1998 gives you interest and fixed compensation, and your terms should not accidentally give that up.

An occupied house, scaffolding and the neighbours

The customer is living in the property while the roof is opened. The terms should cover working hours, access and keys, use of water and power, where materials and skips go, protection of existing finishes, and the dust and disruption that protection reduces but does not remove. Party wall notices are the homeowner's responsibility as building owner, and so is any surveyor's award, scaffold licence or oversail agreement. Say that delay caused by waiting for those, or by a neighbour's objection, extends your programme and is not your liability.

Weather, insurance, building control and defects

While the roof is open the existing house is exposed, and water damage to the rooms below is the most expensive dispute in this trade. The terms should set out your temporary weatherproofing obligations and confirm who insures the existing structure and the works in progress. Structural work here must be notified or certified under the Building Regulations 2010 and sign-off depends on an inspector, and on a domestic project the client's duties under the Construction (Design and Management) Regulations 2015 fall on the contractor or principal contractor, so completion dates should be estimates. Set a defects period and a snagging process, cap liability for business customers, and remember that the Consumer Rights Act 2015 sets a floor for homeowners you cannot contract below.

What it costs

Customer or supplier terms and conditions, £995. One set of terms, customer-facing or supplier-facing, drafted for your business. Five working days.

Review of your existing terms, £495. You already have terms and want them checked and brought up to date. Returned marked up with my amendments and an explanation of the changes. Three working days.

Email me at geoffrey@caesar.co.uk with what you need and any documents, and I will confirm the scope and the fee in writing, usually the same working day. If you would rather pay straight away, buying online forms the engagement on payment: the scope is what the terms and conditions drafting page describes, you accept the Terms of Service at checkout, and I will be in touch promptly to get started.

What you get

• A full set of bespoke terms drafted for your business, reflecting the legal requirements that apply to your business and sector
• A note in plain English explaining the terms I have drafted for you
• Liability, payment, termination and IP provisions that protect your position and are drafted to withstand scrutiny from the other side
• Guidance on how to incorporate the terms properly
• Your questions and comments answered by email or phone
• One round of amendments to finalise the terms ready for use

What is not included

• Negotiating your terms with individual customers (I am happy to quote for this as an additional service if required)
• Sector-specific regulatory compliance beyond the contract terms themselves
• Website privacy notice and cookie compliance, which I quote separately
• Terms governed by the law of another country
• Tax advice

Questions I am often asked

What if the party wall surveyor or building control holds the job up?

That belongs in an extension of time clause. Your terms should list the events that push the programme back, including waiting for a party wall award, an inspector's visit, a neighbour's objection or a decision the customer has not made, and treat dates as estimates. Without it, an overrun nobody controlled becomes your breach.

Do I need different terms when I build for a developer or a landlord?

One document can cover both if the consumer wording and the business wording are kept separate. Work for a developer or landlord who is not a residential occupier is caught by the Housing Grants, Construction and Regeneration Act 1996, which implies adjudication rights, payment notice rules and staged payments on longer contracts, and bans pay when paid.

The customer wants to hold money back until the completion certificate. Should I agree?

Many builders do, and it can help win the job. Agree it only in writing: a stated sum, a stated release date, and a right to be paid if certification is delayed for reasons that are not your fault. Open ended money held against a certificate issued by somebody else may take a long time to recover.

Related guidance and services

• Terms and conditions drafting, £995, the service this page describes
• Contract review, £495
• Consultancy and contractor agreements, £595
• Terms and conditions for a builder doing domestic work
• Terms and conditions for a roofing business

This page is general guidance for businesses in England and Wales, not advice on your own circumstances. Last reviewed: September 2026. Email geoffrey@caesar.co.uk.