Draughty, misted or dated windows? GSS designs, supplies and installs high-performance replacement windows and doors that cut heating bills, cut noise and add real value to your home.
Most UK homes built before 2005 lose significant heat through old windows. Replacing them delivers measurable savings, comfort and kerb appeal — backed by rigorous testing and a 10-year warranty.
Engineered product for deep comfort, all made to measure for UK properties.
High-performance thermally insulated casement window. 75mm-deep frame with deep triple-glazing capacity and acoustic options, engineered for UK homes.
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Thermally insulated heritage door with authentic period detailing and premium hardware. Traditional character meets 21st-century thermal performance.
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Architectural pivot entrance system with a 100mm deep structural profile. Monumental entrance design for luxury self-builds and grand coastal villas.
View Details →Whether your home is Victorian, mid-century or new-build, we have a collection engineered to match its character.
Neat sightlines, solid structure & reliable performance. Well-suited for modern new builds, extensions & high-end residential projects.
Floor-to-ceiling sliding doors, casement units and corner glazing. Maximize glass area with ultra-slim frames to seamlessly connect indoor living to the outdoors.
Authentic heritage detailing with premium copper hardware, for Listed buildings and conservation areas. Looks traditional, performs like 21st-century engineering.
Transparent pricing, no hard sells, and every step project-managed by your dedicated GSS surveyor.
A GSS surveyor visits your home, measures every opening and recommends the right system.
Full itemised pricing within 48 hours. No hidden extras, no price hikes later.
Every unit fabricated to your exact dimensions in our UK partner factory.
Fully-qualified fitters, dust sheets, and your home left clean every day.
Your building regulations compliance certificate and warranty documentation issued within 30 days.
A selection of recent residential replacement and envelope projects across London and the South East.
Case Study
Residential façade restoration — 42 apartment units with full window replacement and brickwork remediation.
Case Study
Residential envelope survey & remediation — Grade II listed building with heritage sash window replacement.
Before & After
Full-house window replacement — 1930s semi with timber windows upgraded to TW75 aluminium casements in white.
Everything you need to know about window and door replacement. Can't find your answer? Give us a call.
Usually no — replacements fall under Permitted Development if the new windows are similar in appearance to the originals. Consent may be needed in Conservation Areas or for Listed Buildings. We'll advise during your free survey and handle any necessary applications.
A typical 3-bed house takes 1–3 days depending on the number of windows and complexity. The exact timeline is included in your written quote. We work room by room to minimise disruption, and your home is secured every evening.
We remove and recycle responsibly. All uPVC, aluminium and glass go through certified recycling channels. Nothing goes to landfill if it can be reprocessed — it's part of our environmental commitment.
Covered for 10 years against manufacturing and installation defects. Your certificate arrives within 30 days of completion.
Aluminium offers the slimmest sightlines, exceptional durability and heritage-style options. uPVC is the best-value choice with low maintenance and excellent thermal performance. We'll recommend based on your home, not our margin — both have their place.
It depends on size, frame system and glazing specification. As a rough guide, uPVC casement windows start around £550 each and aluminium from £850. Your written quote includes exact U-values, all fittings and fixed, itemised pricing — no hidden extras.
Still have questions? Call us on +44 (0) 20 4542 7307
Book a Free SurveyTell us about your project and a GSS surveyor will call you within 24 hours to arrange a free home survey. No hard sells, no pressure — just honest, engineering-led advice.
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