Golden Ratio Sash Windows & Doors is London's premier specialist in the restoration, manufacture, and installation of traditional timber windows. Serving North and West London (including Islington, Hampstead, and Muswell Hill), our time-served craftsmen use traditional joinery methods and premium materials like Accoya to faithfully replicate original features. We are experts in working within Conservation Areas and on Grade II listed buildings. Our services range from bespoke double-glazed sash windows and casement window replacements to elegant French doors and draught-proofing. We pride ourselves on a "no mess" service, punctuality, and a 10-year guarantee, helping you preserve your home’s heritage while improving energy efficiency.