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Topic 20

Design & build and construction

Choosing how to build, agreeing contracts and payments, managing site work and preparing for completion.

31 articles

Choosing how to build

01Design & build vs an architect plus a separate builderDesign & build puts design and construction under one main contract; a traditional arrangement appoints the design team separately from the builder. The useful comparison is how much design control, coordination and independent checking each appointment actually provides.02What a design & build contractor takes responsibility forA design & build contractor takes the design and construction responsibilities allocated to it by the contract. The label does not mean that every approval, professional service, unknown site condition or client obligation is included automatically.03How to choose a builder: checks, accreditations and reviewsChoose a builder by checking the business you will contract with, relevant completed work, references, competence and insurance—not by reviews or a logo alone. Obtain a written offer against a clear scope before making the appointment.04Comparing quotes like-for-like, and why prices vary so muchQuotes are comparable only when they price the same design, specification, responsibilities and assumptions. Compare the scope and unresolved allowances before deciding which headline price represents the better offer.05Estimate, quotation or fixed price: what's the difference?An estimate is an indication of likely cost; a quotation is an offer to do stated work for a stated price. A fixed-price agreement still needs a defined scope and clear rules for changes and other permitted adjustments.06The danger of the cheapest quoteThe lowest quote is not necessarily unsafe or poor value; the risk is accepting it without checking what has been omitted, left provisional or transferred to you. Investigate a large price difference before treating it as a genuine saving.

Contracts and payments

07Do I need a written contract? JCT homeowner and design & build contractsUse a written building contract that matches the project, even though an agreement can exist without a signed standard form. JCT offers homeowner contracts and separate design & build forms; the right choice depends on the work, design responsibility and administration arrangements.08Deposits, stage payments and valuationsAgree deposits and stage payments before work starts, linking them to clear deliverables and a process for checking the amount due. A payment request, a valuation of completed work and an advance for future goods are different things.09RetentionRetention is money withheld from contract payments under an agreed clause and released at the stages specified in that clause. It is not an automatic homeowner entitlement or a substitute for inspecting the work and following the contract.10Provisional sums and prime cost sumsA provisional sum allows for work that is not fully defined when the price is agreed; a prime cost sum usually allows for specified materials or goods whose exact selection remains unresolved. Neither should be mistaken for a fully priced, all-inclusive package.11Variations and extras: how changes are priced and agreedA variation is a change to the agreed work, dealt with under the contract's change procedure. Record the instruction, price basis and programme effect before proceeding wherever possible, rather than leaving an informal request to become a disputed extra.12How much contingency should I allow?Set contingency from the project's unresolved risks, not an automatic percentage applied to every extension or refurbishment. Keep it separate from the agreed scope and review it as investigations, design decisions and construction reduce or change the uncertainty.13Your 14-day cancellation rightA 14-day cancellation right can apply to qualifying consumer contracts made away from the trader's premises or at a distance, but it is not a universal right for every building project. New-building contracts and certain major conversions are excluded, and early-start requests and bespoke goods need separate attention.14The final accountThe final account reconciles the contract price with properly assessed changes, allowances, other contractual adjustments and payments already made. It should explain the final balance, not merely present a last invoice with an unexplained total.

Before work starts

15Health and safety for homeowners (CDM 2015)CDM 2015 applies to domestic building projects, but a homeowner’s client duties normally pass to the contractor or principal contractor. Confirm the appointments, information and safety arrangements before work starts; owning a home does not make construction work exempt.16Insurance: what the builder needs, and telling your home insurerCheck the builder’s insurance and tell your own insurer about the proposed works before they start. Public liability, employers’ liability, professional indemnity and cover for the works or existing house protect against different risks; one certificate does not cover everything.17Skip permits, scaffold and hoarding licences, parking bay suspensionsUsing the road or pavement for a skip, scaffold, hoarding or site access can require separate highway permissions, and occupying a parking bay can require a suspension as well. Planning permission does not replace the council’s licence process.18Construction management plans required by London boroughsA construction management plan explains how the building work will be organised to limit disruption and protect surrounding streets and neighbours. London councils may require one through a planning condition, so check whether it must be approved before any work starts.19Moving gas and electricity meters, temporary site power and waterMeter moves and temporary supplies need early coordination because the network connection, billing meter and installation inside the property can involve different organisations. Confirm the responsible network operator and supplier before the building design fixes a new meter position.

On site

20What happens on site: the stages of the buildA build progresses through preparation, setting out and structural work, enclosure, services and finishes, then testing and handover. The exact order depends on the design and existing building, and inspections must be planned before important work is covered up.21The programme, delays and extensions of timeThe programme sets out the planned sequence and completion date; an extension of time changes the contractual completion date only where the contract allows it. A delay does not automatically entitle the builder to extra time, extra money or both.22Lead times for steel, windows and kitchensThere is no reliable single lead time for all steelwork, windows or kitchens. Obtain a written programme for the actual specification that separates design approval, measurement, manufacture, delivery and installation, then build those dependencies into the construction programme.23Living at home or moving out during the worksStaying at home is an option only where the contractor can maintain safe separation, access and essential facilities throughout the work. Agree the arrangement phase by phase and with your insurer; being comfortable with disruption is not the same as the site being safe to occupy.24Working hours, noise, dust and keeping neighbours informedAgree working arrangements with the contractor and check the council’s conditions and noise requirements for the address. There is no single permitted working-hours schedule for every London borough, and neighbour notification does not override noise controls or planning conditions.

Completion

25Practical completion and snaggingPractical completion is the contractual point at which the works are considered complete to the required practical standard; snagging records outstanding defects or unfinished items. Neither term means that building-control approval, every document and every payment obligation have automatically been dealt with.26The handover pack: certificates and documents you should receiveThe handover pack should contain the project’s completion records, relevant certificates, final drawings, operating instructions and warranty information. Agree the required documents before construction, then check them against what was actually built rather than accepting a generic bundle at the end.27The defects periodThe defects period is the contractual period for identifying and dealing with specified defects after completion. Its length and procedure come from the contract; it is not a universal warranty period or a deadline after which the builder necessarily has no further liability.28Guarantees, insurance-backed guarantees and structural warrantiesA contractor’s guarantee, an insurance-backed guarantee and a structural warranty are different forms of protection. Compare the covered work, claim trigger, exclusions and provider—not just the number of years printed on the certificate.

When things go wrong

29Disputes with a builder: from complaint to adjudicationStart a builder dispute with a written description of the problem, supporting evidence and the remedy sought, then follow the contract’s dispute procedure. Adjudication is not an automatic statutory right for every homeowner: residential-occupier contracts are treated differently from qualifying commercial construction contracts.30What happens if a builder goes bust?If the builder becomes insolvent, first protect people and the unfinished property, establish the company’s formal position and preserve the project records. Recovery of money, use of materials and appointment of a replacement depend on the contract, ownership and available insurance—not simply on who is standing on site.31Defects found after completionA defect discovered after completion should be recorded, assessed and reported promptly; completion does not itself end every contractual, insurance or statutory remedy. The right route depends on the cause, seriousness, dates and relevant contract or policy—not just whether the defects period has expired.