Roofing contracts: JCT, retentions and defects periods
Updated 23 October 2026 · SEO Dons Editorial
A re-roof contract settles what is built and when, how the contractor is paid, what happens if the roof fails after handover and how disputes are resolved. This guide explains the terms that matter. It is information, not legal advice; a contract administrator or solicitor should review the actual documents.
Which JCT contract suits a commercial re-roof?
| Form (2024 edition) | How JCT describes it | Likely fit |
|---|---|---|
| Minor Works (MW) | Smaller, basic projects of a simple nature. The employer supplies drawings, a specification or work schedules; lump sum with monthly interim payments. Not suitable where bills of quantities, detailed control procedures or named specialists are needed. | A single-system re-roof with a clear specification |
| Intermediate (IC) | The employer supplies drawings and bills of quantities, specification or work schedules; can cover named specialists. | A phased re-roof with named specialists |
| Repair and Maintenance (RM) | Repair and maintenance of a building; not suitable for periodic work over a fixed period, where JCT points to its Measured Term Contract. | A repair programme; see maintenance contracts for term work |
If the contractor is to design specific parts of the works, JCT says the Minor Works form with contractor's design must be used. JCT withdrew its 2016 edition on 31 March 2026, allows a transitionary period to 31 December 2026 and recommends the 2024 edition for new projects. In Scotland, JCT refers users to the SBCC suite. MW contracts are normally administered by an architect or contract administrator, so appoint one before signing.
What is a retention, and what is changing?
RICS describes retention as a contractual deduction that protects the client if defects are not rectified. It says the JCT default is a set percentage, 3% or 5% depending on the form, and that users can insert nil. A retention bond, which RICS calls a form of insurance-backed guarantee, is one alternative.
The law may change. GOV.UK says the Commercial Payments Bill, introduced to Parliament in May 2026, would prohibit deducting and withholding retention payments under construction contracts, with further consultation on timing and a lead-in period. RICS reports that new rules are not expected before 2027 at the earliest, with a likely transition of 12 to 24 months. A CMS lawyer writing on JCT's site in May 2026 advised that retention clauses remain lawful for the time being. Check the bill's progress, and decide what security you would want if retention were nil.
What is the difference between practical and final completion?
Practical completion is when the works are finished apart from trifling defects, so the building can be used as intended. "Final completion", the term most people use for the later stage, is when the rectification period has ended, defects are made good and the remaining retention is released.
RICS says practical completion is easier to recognise than to define, and that JCT does not define it except in the 2016 Major Project form. RICS summarises the Court of Appeal position as works free from patent defects other than trifling ones. According to RICS, certifying it:
- starts the final account process and the rectification period;
- releases part of the retention (RICS lists release of 50% of retention monies);
- ends liability for delay damages;
- passes liability, maintenance and insurance of the works to the client.
RICS notes prerequisites such as the health and safety file and test certificates. On a roof, write the building control or competent person certificate, the guarantee documents and the as-built details into the contract as conditions of completion. RICS also says to check who has authority to review quality: under JCT, the contract administrator.
What is a rectification period, and what happens when it ends?
RICS describes a period after practical completion in which the employer tells the contractor about defects and the contractor must return and remedy them at no cost to the employer. When it ends, any claim for later defects would need to be for breach of contract. In the JCT suite, RICS says, a certificate of making good is then issued and the client releases the retention sum. Leaks can take a wet season to show, so ask the designer whether the period in the contract particulars suits the system.
A manufacturer or insurance-backed guarantee is a separate document from the building contract, with its own issuer, term and conditions; the guarantees page explains the types. Funders, tenants or buyers may need collateral warranties, which RICS says JCT deals with, alongside bonds and guarantees, in section 7 of its standard, intermediate and design and build contracts.
What are liquidated damages, and do they matter on a roof?
RICS says that with liquidated damages the parties have predetermined the sum payable for specific periods of delay, rather than claiming general damages for breach. The rate and dates sit in the contract particulars. For a phased roof on an occupied building, check that the dates reflect the programme in the specification.
What do the Construction Act's payment rules mean?
Part 2 of the Housing Grants, Construction and Regeneration Act 1996 applies to construction operations, which section 105 defines to include the repair and maintenance of buildings, so a commercial re-roof or repair is within it:
| Section | Rule |
|---|---|
| 109 | Right to stage payments, unless the work is specified to last less than 45 days. |
| 110 | The contract needs a mechanism for what becomes due and when, and a final date for payment; otherwise the Scheme for Construction Contracts applies. |
| 110A | A payment notice stating the sum and its basis, not later than five days after the payment due date. |
| 111 | The payer pays the notified sum by the final date for payment unless it gives a pay less notice in time. |
| 112 | A contractor not paid in full may suspend work after at least seven days' notice. |
| 113 | Pay-when-paid clauses are ineffective, except where a third party is insolvent. |
| 108 | Right to refer a dispute to adjudication; a decision is due 28 days from referral unless extended. |
Diarise payment and notice dates at the start; a late or missing notice can leave the client owing the notified sum.
What should be settled before signing?
- The form, the edition and the contract administrator.
- The specification and drawings the price rests on: see what a re-roof tender must say.
- Dates and phasing, the liquidated damages rate, the retention percentage or its alternative, and the rectification period.
- Insurance and competence, covered in how to choose a commercial flat roofing contractor and SSIP, CHAS and Constructionline explained.
- The completion paperwork, set out in the completion certificate guide.
To talk through a contract for your roof, you can send an enquiry through the form on this page.
Sources
- Minor Works Building Contract, JCT (corporate site) (checked 22 October 2026).
- Minor Works Building Contract (MW 2024), JCT (online store) (checked 22 October 2026).
- Intermediate Building Contract (IC 2024), JCT (online store) (checked 22 October 2026).
- Repair and Maintenance Contract (RM 2024), JCT (online store) (checked 22 October 2026).
- JCT 2016: withdrawal and transitionary period explained, JCT (checked 22 October 2026).
- Retention reform and the future of construction payment practices, JCT (blog by CMS, first published May 2026) (checked 22 October 2026).
- Government proposes an end to retentions, RICS Construction Journal (checked 22 October 2026).
- What are the alternatives to retention?, RICS Construction Journal (checked 22 October 2026).
- Why professionals should be wary of practical completion, RICS Construction Journal (checked 22 October 2026).
- An A-Z of contract administration for APC, RICS Built Environment Journal (checked 22 October 2026).
- How claims under contract differ from those for breach, RICS Construction Journal (checked 22 October 2026).
- Commercial Payments Bill: overview, GOV.UK (checked 22 October 2026).
- Housing Grants, Construction and Regeneration Act 1996, Part 2 (sections 105 to 113), legislation.gov.uk (checked 22 October 2026).
Common questions
Is practical completion the same as final completion?
No. Practical completion is certified when the works are finished apart from trifling defects, and it starts the rectification period. The later stage is when defects have been made good, a certificate of making good is issued and the remaining retention is released.
How much retention can a client hold?
The contract sets it. RICS says the JCT default is a set percentage, 3% or 5% depending on the form, with the option to insert nil. GOV.UK says a ban is planned through the Commercial Payments Bill, which was a bill, not law, when this was checked.
Do the Construction Act payment rules apply to a roof repair?
Section 105 includes the repair and maintenance of buildings in construction operations, so a commercial roof repair falls within Part 2 of the Act. The exception in section 106 is for contracts with a residential occupier, which relates to dwellings.