House Extensions in Harrow
RCB Design & Build | A2Z Principal Contractors works across Harrow on the Hill, North Harrow, South Harrow, and the wider HA1, HA2, and HA3 postcode areas, delivering loft conversions, rear extensions, full house refurbishments, and structural alteration works for homeowners across the borough. Harrow's housing stock spans Victorian and Edwardian terraces in the central areas, 1930s semis in the outer residential zones, and larger detached properties around Harrow on the Hill and Pinner Road. Th
House Extensions in Harrow — what to expect
Single-storey kitchen and dining room extensions are among the most popular projects across the Harrow borough. We handle planning, structural work, drainage, and internal decoration as a single integrated package.
Harrow property types
means the right approach to a loft conversion or extension varies significantly depending on the specific house, and we bring that awareness to every project. The property type affects which extensions approach works best — we'll advise from the first call.
Common extensions projects we deliver in Harrow
How we deliver extensions in Harrow
Free consultation & survey
We visit your Harrow property, assess what's possible, and give you a fixed-price indication before you commit to anything. No obligation.
Design & planning support
We work alongside your architect or our preferred design partners to develop drawings that are buildable, compliant, and cost-effective. We flag planning and permitted development options early.
Fixed-price contract
You receive a detailed, itemised scope of works and a fixed price before we start. No surprises mid-project. Variations are agreed in writing before any additional work begins.
Managed delivery
We manage all trades, procurement, and site logistics. You have a single point of contact throughout. Our site teams are familiar with Harrow and the local planning and building control requirements.
Sign-off & warranty
We complete to building regulations standard and obtain all relevant sign-off. Your structural warranty covers up to 25 years.
Planning in Harrow
**Full house refurbishments.** For properties being modernised after purchase or upgraded to a higher specification, we manage all trades — electrics, plumbing, plastering, kitchen installation, bathroom fit-out, flooring, and decoration — in a properly sequenced programme. **Structural alterations
Why choose RCB Design & Build in Harrow?
Local knowledge
We work in Harrow regularly. We know the planning authority, local building control, and the typical property types and challenges in this area.
Fixed-price guarantee
Your price is fixed before work starts. We absorb material and labour cost movements — not you.
Full principal contractor service
We manage every trade, every supplier, every inspection. You deal with one team from start to finish.
25-year structural warranty
All structural work is covered under our long-term warranty. Proof of quality, in writing.
Checkatrade-verified
Over 100 verified reviews from homeowners across London. Independently verified, not self-reported.
Design-and-build capability
We don't just build — we can support design development, planning applications, and pre-construction cost planning.
Other services in Harrow
Start your Harrow project
Free consultation. Fixed price. 25-year warranty. One team from first call to final sign-off.
Or call us on 07359 872594