Written by Mark Reid,
Trades Editor ·Verified 10 October 2026
London's housing stock is genuinely unlike anywhere else in the country. You've got Georgian terraces in Islington and Hackney with their original sash windows, Victorian bay-fronted semis stretching across Lewisham and Ealing, post-war council-built properties throughout Southwark and Tower Hamlets, and newer-build flats in Canary Wharf and Stratford that need entirely different glazing solutions. That variety means window installation in London isn't a single trade so much as a dozen overlapping ones. A company that's brilliant at fitting slim-profile double glazing into a period property in Richmond won't necessarily be your best call for replacing aluminium-framed windows in a 1960s block in Brixton. Conservation area restrictions also come into play across large parts of inner London, particularly in places like Hampstead, Notting Hill, and Greenwich, where you'll need to match original window styles or get specific council approval before any work starts. Prices vary too. A straightforward uPVC casement replacement in an outer London suburb typically runs from around £400 to £700 per window fitted, while custom timber sash windows in a conservation area can reach £1,200 to £2,000 or more per unit depending on size and specification.
The businesses on this page are drawn from third-party public business listings and ranked by their public review rating alongside the total number of reviews they've received, with a small ranking lift given to those that have a working website and a listed phone number. We check each business's homepage to confirm that window installation is genuinely what they primarily offer, which is how we keep unrelated trades off the page. Any listing flagged as permanently closed is removed automatically. Where you see a Trust Verified badge on a listing, that business has gone a step further and passed our full independent verification, which covers trade qualifications and accreditations, public liability insurance, trading history, customer review history, and registered company information. You can see exactly what that process involves on our How We Verify page. For any business on this page that doesn't carry that badge, those checks haven't been carried out by us, and you should do them yourself before committing to any work.
Before you book anyone, ask for a written, itemised quote rather than a verbal estimate, and get at least three from different companies so you've got a realistic sense of market rates for your specific job. Confirm whether the installer is FENSA or CERTASS registered, as both schemes allow installers to self-certify building regulations compliance for replacement windows, which saves you having to involve your local authority separately. Ask specifically about the energy rating of the glazing units they supply, and check whether the guarantee covers both the frames and the sealed units, since failed sealed units that cloud over are one of the most common complaints. If your property is in a conservation area or is listed, get written confirmation from the installer that they're familiar with your local planning requirements before they start. Keep all paperwork, certificates, and guarantees somewhere safe once the job is done.
How We Select & Rate The Best Window Installers in London
Rankings on this page are driven by public review rating and review count pulled from third-party business listings, with a small lift applied to businesses that have a working website and a listed phone number. We check each business's homepage to confirm that window installation is what they primarily offer, which keeps unrelated trades off the page, and any listing flagged as permanently closed is removed automatically. Businesses carrying a Trust Verified badge have additionally passed our full independent verification covering trade qualifications, public liability insurance, trading history, customer review history, and registered company information. See our How We Verify page for the full list. Other businesses featured here have not been independently verified by us, and inclusion is not an endorsement. Always carry out your own checks before hiring.
Recommended and Featured listings are paid placements, so a business's fee affects whether and where it appears. Every other listing is ranked on rating and review count from third-party business listings. How we rank & verify →
London Box Sash Windows Ltd specialises in box sash window installation and repair across Beckenham and the surrounding London boroughs. The company focuses exclusively on sash and traditional window styles, making it a considered choice for period and Victorian properties where like-for-like replacement matters.
SDG Windows Ltd provides professional window installation services from their base in South East London. They serve properties across London with reliable glazing solutions and expert fitting services.
Absolute Roof Windows specialises in the supply and fitting of roof windows and skylights for homes in Sutton. The company works on loft conversions and existing roof spaces alike.
The London Sash Window Company specialises in sash window installation and restoration services throughout London. They provide expert window installation services for both period properties and modern homes across the capital.
The Door & Window Centre Ltd is a window and door installation company serving Orpington and the surrounding area. The business supplies and fits a range of residential glazing and entrance products. Customers looking for a local, independently run installer rather than a national chain will find a straightforward point of contact here.
Homeglaze Home Improvements is a window installation company serving Romford and the surrounding area. The firm fits double glazing, replacement windows, and related home glazing products for residential customers. Its website at homeglaze.co.uk outlines the full range of options available.
SJB Sash Windows Specialist Ltd provides professional window installation services from their Carshalton base, serving London and surrounding areas. The company specialises in sash window solutions. Their experienced team focuses on both traditional and modern window installations for residential and commercial properties.
Generation Windows UK Ltd is a window installer serving Sutton and the surrounding area. The company installs windows and doors for residential properties, offering homeowners straightforward installation work without the hard sell.
Core Sash Windows brings a focused specialism to the London market, working exclusively with sash and timber window installation and restoration. The company serves residential clients across the capital who are maintaining period properties or seeking like-for-like replacements.
Sidcup Windows & Doors specialises in window installation services for residential and commercial properties in the Sidcup area and surrounding London boroughs. Based in Sidcup, the company serves neighbouring communities with professional window fitting solutions.
Window installation and supply across Romford and the surrounding Kent borders is the core work of All Kent Windows Limited. The company fits replacement windows for domestic properties. Its name reflects a regional focus that extends beyond a single town, making it a practical option for homeowners across that stretch of south-east London and north Kent.
Window installation across London, with Wembley Windows SC Ltd covering domestic and commercial properties. Supply and fitting of replacement windows forms the core of its work.
Ask Windows Limited is a window installation company serving London. The firm focuses on residential and commercial glazing, covering supply and fitting across the capital. With a straightforward name that reflects its trade, it offers a clear point of contact for homeowners and businesses looking to replace or upgrade windows.
Wandsworth Sash Windows specialises in the installation and restoration of traditional sash windows across London, operating from their base in Lower Sydenham. Their skilled craftsmen work throughout the capital, helping property owners maintain the period character of their homes while improving energy efficiency and security.
Sash window restoration and installation is the core focus for London Sash Windows & Doors Ltd, a specialist working across London. The company handles both period property repairs and new sash installations, making it a practical option for homeowners dealing with draughty or failing timber windows.
SPS Timber Windows Limited specialises in the supply and installation of timber windows across London. Working exclusively in wood rather than uPVC or aluminium, the company occupies a distinct niche for homeowners and contractors seeking period-appropriate or bespoke joinery.
Romford Windows Ltd specialises in double glazing installation services from their base in Romford. They focus on window installation solutions for residential and commercial properties throughout Romford and surrounding districts.
Window installation in Bromley is the focus of Metroglaze London Ltd, covering replacement units and fitting for domestic properties across the area. Work is carried out directly for local households rather than through subcontracted teams.
A1 Window Construction Ltd provides professional window installation services across London from their Wallington base. They serve residential and commercial clients throughout the London area, offering expert fitting and replacement services for various window types.
Roberts Windows Ltd provides window installation services across London from their base in Beckenham. Their experienced team handles residential window fitting projects throughout the capital.
Crestshield Windows Ltd installs windows and doors for residential properties in south-east London. Customer feedback points repeatedly to clean installation work and clear communication throughout each job.
Astral Security Windows is a Sutton-based installer working on conservatories and double glazing. The company covers Surrey and surrounding areas. Enquiries can be made via the website for further detail on services offered.
Window installation across London, with a focus on residential properties in and around North London. The company handles supply and fitting, covering the range of frame materials and glazing options typical of a full-service window installer.
Rise Windows provides professional window installation services throughout Beckenham and the surrounding area. The company operates from Elmers End, and its experienced team specialises in fitting replacement windows for residential and commercial properties across South London.
Herts Glass Windows and Doors Ltd is a firm of window installers serving London and the surrounding area. The company fits windows and doors for residential properties.
Transparency notice: Recommended and Featured listings are paid placements, so a business's fee affects whether and where it appears. All other listings are ranked by a combined score drawn from ratings and review counts published on third-party business listings, plus basic completeness signals such as a working website and phone. A Trust Verified badge means we have independently checked that business's documents; businesses without it have not been independently verified by us. How we verify →
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Window installation costs vary significantly across London. Basic uPVC double glazing starts around £300-500 per window, whilst timber sash window restoration can run £800-2000 per window depending on condition. Heritage glazing for listed buildings often costs £1500-3000 per window. Location affects pricing too - central London jobs typically cost 20-30% more than outer boroughs due to access restrictions and parking charges. Always get three quotes to compare.
Do I need planning permission for new windows in London?
Most window replacements fall under permitted development rights, but many London properties sit in conservation areas where restrictions apply. Listed buildings always need consent for window changes. Even in conservation areas, like-for-like replacements often get approval, but changing materials (timber to uPVC) usually doesn't. Check with your local council's planning department before starting work, as unauthorised changes can be expensive to rectify.
What's the difference between FENSA and Certass registration?
Both FENSA and Certass are government-approved schemes that allow window installers to self-certify their work meets building regulations. This saves you applying for building control approval separately. FENSA is the larger scheme with more members, whilst Certass covers similar ground. Either registration is fine - what matters is that your installer belongs to one of these schemes for replacement window work.
How long does window installation typically take in London?
A typical London house with 8-10 windows usually takes 2-3 days for complete replacement, though Victorian terraces with original features might need longer. Single window replacements often complete in half a day. Sash window restoration takes longer - expect 1-2 weeks per window as they're often removed to workshops. Access issues in London (narrow streets, parking restrictions) can extend timescales, so discuss logistics upfront.
Should I choose timber, uPVC, or aluminium windows?
Your choice depends on budget, maintenance preferences, and planning constraints. uPVC offers good value and low maintenance but isn't suitable for conservation areas or listed buildings. Timber provides authentic appearance for period properties but needs regular upkeep. Aluminium works well for modern homes and offers slim sightlines, but costs more than uPVC. Many London boroughs have specific requirements, so check local planning guidance first.
How do I verify a window installer's credentials and reputation?
Start by confirming FENSA or Certass registration on their official websites. Check the installer's Companies House listing shows active trading status and recent accounts. Ask for references from jobs completed in the last year, preferably in your area. Verify their insurance covers public liability (minimum £2 million) and get this in writing. Look for consistent Google reviews over time rather than just high ratings, and be wary of installers who cold-call or demand large upfront payments.
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