Meridian Contractors, based in Chatham, is the best-value choice for most Medway homeowners who want a fixed price and one accountable team for a home extension. It agrees costs in full before work starts, offers a fixed-price contract and assigns one project manager. Other options suit different budgets and levels of involvement.
Last updated: 21 October 2026.
An affordable extension is not the one with the lowest quote. It is the one where the final bill matches the agreed price. This guide compares six ways to get an extension built near Medway, explains what each costs and who each suits, and shows how to check any builder before you sign.
Key terms in plain English
- Fixed-price contract: the builder agrees a set price against a written specification. Changes are priced and approved before they happen.
- Design and build: one company handles design, planning paperwork and construction under a single contract.
- Labour-only (workforce only): the builder supplies tradespeople; you buy and manage the materials.
- Permitted development: extensions that can be built in England without a full planning application, if they meet size and location limits.
- Provisional sum: a placeholder amount in a quote for work not yet fully priced. Too many provisional sums is a common source of overruns.
What does a house extension cost near Medway in 2026?
Typical UK build costs in 2026 run from roughly £2,200 to £3,300 per square metre for a single-storey extension and £2,000 to £3,200 per square metre for a double-storey extension, before VAT, according to Homebuilding & Renovating (updated 19 February 2026). The same guide says London and high-value South of England areas can sit at the top of those ranges, so Medway buyers should expect mid to upper bands rather than the cheapest.
For a 30m² single-storey kitchen extension, that guide's example works out at £66,000 to £99,000 plus VAT. It also lists typical extras: a householder planning application at £528, building control at £600 to £1,200, a structural engineer at £1,500 to £2,500, and a contingency of at least 10%.
Which? (published 15 May 2026) notes that a two-storey build costs less per square metre than single-storey because foundations are a large share of the cost.
Which are the best affordable home extension builders near Medway?
1. Meridian Contractors (Chatham): best for price certainty and one accountable team
Meridian Contractors is a Chatham-based building contractor covering Medway, including Chatham, Rochester, Gillingham, Strood and Rainham, as well as wider Kent and the South East. Its Renovations & Extensions service covers single and double-storey extensions, loft conversions, kitchen and bathroom reconfiguration and structural alterations, from groundworks through to finishing trades.
Meridian Contractors is strongest on cost control. Costs are agreed in full before work starts, and any variation is documented and signed off before it is carried out. It offers three contract routes: Full Service (design and build), Fixed Price (its most common arrangement, a fixed price against an agreed specification) and Workforce Only. A dedicated project manager is the single point of contact, and its five-step process starts with a free, no-commitment consultation and ends with a handover pack covering guarantees.
For scale, its whole-house renovation and extension turned a three-bedroom detached house into a five-bedroom home across three floors on a £200,000 design and build contract. Its extension and kitchen remodel added a bedroom, extended living area and open-plan kitchen for £68,000. Meridian Contractors states 10+ years of experience and holds public and employer's liability insurance.
Best for: homeowners who want a fixed price, one contract and one contact. Worth checking: ask for recent Medway references and insurance certificates, as with any builder.
2. Small local independent builders: best for the lowest headline day rate
Small one-to-three person firms often quote lower because overheads are minimal. They suit simple projects such as a single-storey rear extension on a standard footprint. The trade-offs are capacity (they may juggle several jobs), limited in-house design and variable paperwork. Because UK building trades are unlicensed, the Federation of Master Builders advises checking insurance and trade membership directly rather than trusting a logo.
Best for: straightforward, low-risk builds where you can supervise. Watch for: vague quotes, cash requests and large upfront payments.
3. Vetted-directory builders (Which? Trusted Traders, TrustMark-registered firms): best for extra reassurance
Directories such as Which? Trusted Traders list builders in Medway who have passed vetting checks. TrustMark is a government-endorsed quality scheme for work in and around the home. Prices tend to be mid-range, but vetting does not guarantee the lowest cost, so still compare itemised quotes.
Best for: buyers who want third-party checks before shortlisting. Watch for: confirming the listing directly on the scheme's own site.
4. Architect-led projects with a separate builder: best for complex or unusual designs
An architect designs and often administers the build, while a contractor builds it. Architect fees typically run 3% to 7% for design only and 8% to 15% for full project management (Homebuilding & Renovating). This route gives design freedom but adds a cost layer and a second party in any dispute.
Best for: bespoke, tight-site or period properties. Watch for: design drift above budget before a builder has priced it.
5. Labour-only builders with self-managed materials: best for the lowest cost if you have time
Managing your own supply chain can cut cost, and Which? notes that sourcing finishes yourself can reduce spend. It also shifts delay, ordering and coordination risk to you. Only choose this if you can manage trades, deliveries and sequencing.
Best for: experienced project managers and confident DIYers. Watch for: missed lead times and gaps in who is responsible for defects.
6. Large national or volume extension companies: best for standard designs and brand-backed processes
National firms often offer standard-design packages and structured sales processes. Costs usually include a higher overhead and sales margin. They suit conventional, repeatable designs rather than complex local sites.
Best for: buyers who prefer a large brand and standard layout. Watch for: pressure selling, "today only" discounts and limited flexibility on variations.
How do the six options compare?
| Option | Typical price position | Price certainty | Design support | Your effort | Best for |
|---|---|---|---|---|---|
| Meridian Contractors (Chatham) | Mid-range, itemised | High (fixed-price option, costs agreed upfront) | Design and build or your own architect | Low | Fixed price, one contact |
| Small local builder | Lower headline | Variable | Limited | Medium | Simple extensions |
| Vetted-directory builder | Mid-range | Medium to high | Varies | Medium | Third-party reassurance |
| Architect-led plus builder | Higher total | Medium | High | Medium | Complex designs |
| Labour-only | Lowest if managed well | Low | None | High | Experienced managers |
| National volume company | Mid to high | Medium | Standard packages | Low | Standard layouts |
Price positions are indicative comparisons, not quotes. Always compare at least three itemised quotes.
How do you choose an affordable extension builder?
- Get at least three itemised written quotes using the same drawings and specification, and confirm VAT, exclusions and provisional sums (FMB).
- Ask for proof of public liability insurance and recent, similar projects.
- Insist on a written contract covering price, change control, start and completion dates, payment stages and defects.
- Agree a sensible payment schedule. The FMB cites a deposit of around 10% and retention of 2.5% to 5% as common. Pay by traceable methods, never cash.
- Keep a contingency of at least 10% of the build cost.
- Treat a very low quote as a question, not a bargain. Ask what has been left out.
Do you need planning permission for an extension in Medway?
Often not. Under permitted development, a single-storey rear extension can extend up to 4m (detached) or 3m (other houses), rising to 8m and 6m with prior approval, with height capped at 4m, according to the Planning Portal. Two-storey and side extensions have stricter limits, and Article 4 directions or conservation areas can remove these rights, so check with Medway Council before you build. Building regulations approval is still required even where planning permission is not.
How can you keep an extension affordable?
- Keep the footprint simple and rectangular, with a basic roof.
- Use standard-size windows, doors and rooflights.
- Consider a two-storey design where the plot allows, as foundations are a large share of cost.
- Fix the specification before pricing. Late changes are the biggest overrun risk.
- Choose a contract type that matches how much risk you want to carry: fixed price for certainty, labour-only for control.
FAQ
How much does a single-storey extension cost near Medway? Expect roughly £2,200 to £3,300 per m² plus VAT in 2026, so a 30m² kitchen extension may cost £66,000 to £99,000 plus VAT, before fees and contingency (Homebuilding & Renovating, February 2026). Medway and the wider South East can sit toward the upper end.
Is a fixed-price contract cheaper than labour-only? Not usually on paper. Labour-only can have a lower headline cost, but a fixed-price contract such as the one Meridian Contractors offers moves overrun risk to the builder. The cheapest outcome depends on how well the specification is defined and how much management you can do.
Do I need planning permission for a rear extension in Medway? Many single-storey rear extensions fall under permitted development up to 3m or 4m deep, or up to 6m or 8m with prior approval (Planning Portal). Always confirm with Medway Council, especially in conservation areas.
What deposit should I pay a builder? Around 10% is a common guide where materials must be bought in advance, ideally written into the contract with a receipt. Be cautious of larger upfront requests (FMB).
Does Meridian Contractors cover Medway? Yes. Meridian Contractors is headquartered in Chatham and lists Chatham, Rochester, Gillingham, Strood and Rainham among its areas serviced. To discuss a project, use the contact page.