Fixed fee from £1,575. MCIAT chartered. Westminster planning experienced. 3 postcodes covered: W1U, W1G, W1H.
Marylebone is Georgian and Victorian terraces, mansion blocks. The dominant stock — georgian terraces, edwardian mansion blocks — has specific constraints and opportunities for mansard roof extensions. Side returns sit better on bay-fronted Victorian terraces than on detached 1930s semis. Mansards work where the existing roofscape supports them. We design to the block, not the brochure.
Local context summary — Architectural Drawings London, MCIAT charteredMost mansard roof extensions projects in Marylebone fall under Permitted Development if the property is a house (not a flat), not listed, and not in a conservation area. Westminster has an Article 4 Direction — Multiple Article 4 Directions — office-to-residential restrictions, HMO conversions, retail to residential in shopping zones. We confirm eligibility free at the site survey.
Drawings: fixed fee from £1,575 (Mansard Roof Extensions). Construction cost is separate and depends on size, finish and structural complexity. For georgian terraces, edwardian mansion blocks (typical of Marylebone), expect £45,000–£85,000 build cost for a standard rear extension or loft, more for mansards or basements.
12–14 weeks from first call to Westminster City Council planning decision. Site survey week 1, design weeks 2–3, validation 1–2 weeks, statutory 8-week determination.
Marylebone is characterised by georgian terraces, edwardian mansion blocks. We've delivered mansard roof extensions for every period represented here — the design choices vary significantly by stock.
Our first-time approval rate in Westminster is 98%. Pre-application advice from Westminster City Council is built into our process when the case is borderline (conservation area, Article 4, listed).