Building Contracts for London Home Projects: What You Need to Know

A building project without a proper written contract is a high-risk proposition. The reasons: Scope disputes: without a clearly defined scope of works in the contract, disagreements about what is and is not included in the price are extremely common. "I thought the kitchen was included"; "we didn't price for underpinning the chimney breast" — these are typical disputes that a detailed written scope in the contract resolves. Payment disputes: without a clear payment schedule, contractors may demand payment ahead of the work completed, creating risk for the homeowner. A properly structured payment schedule protects both parties. Programme disputes: without an agreed programme in the contract, it is impossible to establish whether the contractor is in delay, or to calculate any loss caused by delay. Variation disputes: any changes to the scope of works must be agreed in writing with a clear cost and programme impact before implementation. Without contract terms covering variations, every change becomes a potential dispute. Defects disputes: without a contract-defined defects period and retention mechanism, the homeowner has limited practical leverage to ensure the contractor returns to rectify snags. Legal enforceability: a written contract is enforceable in court or through adjudication. An oral agreement is enforceable in principle but extremely difficult to prove.

The most commonly used standard form building contracts for London residential construction: JCT Minor Works Building Contract (MW): the most widely used standard form for straightforward residential projects. Suitable for projects where the homeowner has engaged an architect who administers the contract. Provides: clear scope definition; architect's instructions mechanism; interim payment provisions; practical completion certificate; defects period; retention; insurance requirements. Available from the JCT (Joint Contracts Tribunal). JCT Building Contract for a Home Owner / Occupier (HO/C): specifically designed for homeowners dealing directly with a contractor without an architect. Simpler than the MW contract, appropriate for straightforward single-trade or limited-contractor projects. Available from the JCT website. RIBA Domestic Building Contract: produced by the Royal Institute of British Architects, similar in scope to the JCT homeowner contract. Often used where the homeowner's architect has prepared the contract. FMB (Federation of Master Builders) Standard Building Contract: a simplified standard form produced by the FMB for use by member contractors with residential clients. Bespoke contracts: for larger or more complex projects, a lawyer or contract specialist may draft a bespoke contract. This is rarely cost-effective for residential projects under £200,000 but appropriate for larger new build or significant refurbishment projects. In most London residential extension and refurbishment projects, the JCT MW or the JCT Homeowner contract is the appropriate starting point. Using one of these standard forms — rather than a contractor's own letter of intent — provides a much stronger legal framework.

A building contract for a London residential project should contain: Parties: the full legal names and addresses of the building owner (homeowner) and the contractor (company registered name, registered number, and registered address if a limited company). Description of works: a clear description of the project, referencing the specification, drawings, and any schedule of works as contract documents. Contract documents: list every drawing (with revision numbers), specification, schedule of works, and any other document that forms the basis of the contract. Start date and completion date: the anticipated start on site and the anticipated practical completion date. Programme: a construction programme may be annexed to the contract or referenced as a contract document. Contract sum: the agreed price, inclusive or exclusive of VAT, and the basis on which it was calculated. Payment schedule: the agreed stage payment amounts and the triggers for each payment. Variations: the mechanism for instructing, valuing, and agreeing changes to the scope and price. Practical completion: a definition of practical completion (all works substantially complete, capable of occupation, with only minor defects outstanding) and the mechanism for its certification. Defects liability period: typically 12 months from practical completion. During this period the contractor must rectify any defects that emerge. Retention: the percentage held back (typically 2.5-5%) and when it is released (50% at practical completion, 50% at end of defects period). Dispute resolution: the mechanism for resolving disputes — adjudication (the primary right under the Housing Grants, Construction and Regeneration Act 1996), arbitration, or litigation. Insurance: confirmation of the contractor's public liability and employer's liability insurance, and confirmation of the works insurance arrangements.

The payment schedule in a building contract determines when and how much you pay, and it is the single most important commercial protection for a London homeowner: Stage-based payments: tie each payment to the completion of a defined stage of work (completion of groundworks and foundations; completion of structural works; completion of roof; completion of first fix; completion of plastering; completion of second fix; practical completion). This ensures you never pay significantly more than the value of work completed. Avoid advance payments: do not pay more than 20-25% of the contract sum in advance (as a mobilisation deposit). Paying 50% or more upfront leaves you exposed if the contractor goes into financial difficulty or abandons the project. Retention: hold 5% retention throughout the project and release half at practical completion, half at the end of the 12-month defects period. The retention provides leverage to ensure the contractor returns to rectify snagging items. Final account: no final payment should be made until: the snag list has been agreed and all items resolved; the building regulations completion certificate has been issued; all test certificates (gas, electrics, Building Control) have been handed over; and all guarantees and warranties for the works have been provided. The most common payment mistake in London construction is paying too much too early — leaving the homeowner with little leverage and significant financial exposure if the contractor underperforms.

Despite precautions, contractors sometimes default — they walk off site, become insolvent, or fail to perform the work to the required standard. Steps if a contractor goes wrong in a London project: Issue a formal written notice: if the contractor is in breach of contract (not performing the work, falling significantly behind programme, refusing to fix defects), issue a formal written notice specifying the breach and requiring remedy within a defined period (typically 14 days). Keep all records: document the stage of works, what payments have been made, photographs of defects, all correspondence. Withhold payment: if the contractor is in breach and you have given formal notice, you are entitled to withhold the next payment until the breach is remedied. The contract should specify the withholding notice requirements. Engage a replacement contractor: if the contractor refuses to return or cure the breach after your formal notice, you can terminate the contract and engage a replacement contractor to complete the works. You can claim the additional cost of completion from the original contractor. Adjudication: for disputes over money or performance, statutory adjudication under the Housing Grants Act provides a fast (28-day) and relatively cost-effective dispute resolution mechanism. An adjudicator's decision is temporarily binding and enforceable in court.