Cogsworth — The Architectural Butler
At your service, 24/7. Ask Cogsworth about bespoke residential extensions, commercial developments, planning permission, conservation guidelines, or booking a consultation with Edward Seaman.
Frequently Asked Questions
Clear, transparent answers to the questions homeowners and property developers ask us most.
Any building project involves complex decisions with significant financial, structural, and legal implications. As an RIBA Chartered Practice, we provide a bespoke service guiding you from concept through planning, Building Regulations, and builder tender. We maximise spatial efficiency, ensure planning compliance, and protect your budget while bringing your design vision to life.
External consultants may be required depending on the scale and scope of your build. These often include structural engineers, party wall surveyors, approved inspectors, or drainage survey specialists. We advise on required consultants on a project-by-project basis, coordinate with them directly, and recommend proven specialists.
Statutory planning decisions rest with your local council's planning authority, so no practice can provide a 100% guarantee. However, our extensive experience with local planning policies in London, Hertfordshire, and Buckinghamshire allows us to design specifically to maximise approval probability. Where appropriate, we can also design within your Permitted Development rights to bypass full planning permission entirely.
We regularly design and deliver architectural schemes across London and the Home Counties. Our core areas include Hertfordshire (Watford, St Albans, Kings Langley, Rickmansworth, Radlett), Buckinghamshire (Amersham, Chesham, Chalfonts), and Greater & Central London (Barnet, Harrow, Brent, Ealing, Westminster, Camden, and Hillingdon).
We undertake residential and commercial architecture. Our residential work includes single and double-storey rear extensions, wrap-around extensions, loft conversions, bespoke new-build houses, flat conversions, and sensitive remodels of Listed Buildings and conservation properties. Our commercial portfolio spans retail, hospitality, industrial, and mixed-use developments.
Every project is unique, so our fees are tailored to your required level of service. We provide fixed-fee transparent quotes broken down across the 5 RIBA stages: Concept Design (Stage 0–1), Planning Submission (Stage 2), Detailed Technical / Building Regulations (Stage 3), and Tender & On-Site Delivery (Stage 4). We also offer initial on-site or virtual consultations.
Build costs vary based on specification, ground conditions, and structural requirements. As a benchmark for quality residential extensions in London and the Home Counties, build costs typically start around £2,500 to £3,500+ per square metre plus VAT. We work closely with you and vetted contractors to align design specifications with your target investment.