What does design and build mean?
Design and build means a single contractor is responsible for both design development and physical construction. You work with one business that coordinates design, structural engineering, planning, and delivery — one contract, one point of accountability. RCB Design & Build operates on this model.
What is a principal contractor?
A principal contractor has overall responsibility for coordinating all construction activity on a project. Under CDM 2015, any domestic project involving more than one trade contractor requires a principal contractor. RCB acts as principal contractor on all projects it delivers.
Do I need planning permission for a loft conversion?
Most loft conversions are Permitted Development — no full planning permission needed — subject to volume limits (40m³ for terraces, 50m³ for semi/detached), height limits, and rear-only location. Conservation areas and listed buildings have additional restrictions. We check planning status as part of our pre-construction review.
How much does a rear extension cost in London?
Single-storey rear extension: £38,000–£70,000 for medium specification. Double-storey adds £20,000–£35,000. Main cost drivers: floor area, glazing specification, structural opening required, drainage implications, and finish level. We provide ballparks for early budgeting and formal estimates after a site visit.
How much does a loft conversion cost in London?
Rear dormer: £40,000–£65,000. L-shaped dormer: £55,000–£75,000. Hip-to-gable with rear dormer: £55,000–£80,000. Mansard: £75,000–£110,000. Second-fix materials are client-supplied under RCB's standard contract.
What credentials should a contractor have?
Public liability and employers liability insurance. Membership of the Federation of Master Builders (FMB) or TrustMark — both require vetting and ongoing quality assessment. Checkatrade and TrustATrader for independently verified reviews. RCB Design & Build holds all four.
What is CDM 2015?
The Construction (Design and Management) Regulations 2015 set health and safety duties for construction projects. If your domestic project involves more than one trade contractor, CDM applies and a Principal Contractor must be appointed. RCB acts as a CDM-compliant Principal Contractor on all projects.
What is the difference between a ballpark and a formal estimate?
A ballpark is a broad order-of-magnitude figure produced without full drawings or site information — useful for early budgeting. A formal estimate is produced after a site visit, drawings, structural information, and a confirmed specification. Ballparks can differ from formal estimates by 20–40% in either direction. We provide both at the appropriate stage.
Ready to discuss your project?
Contact RCB Design & Build. Email: contact@rcbGroup.co.uk | Phone: +44 7359 872594 | rcbGroup.co.uk — FMB | TrustMark | Checkatrade | TrustATrader — Verified. Insured. Trusted.