12 Best Window Installers in South East London for 2026

South East London has some of the most varied housing stock in the capital, and that shapes what window work involves here. Around Blackheath, Greenwich and Lewisham you'll find Victorian and Edwardian terraces with timber sash windows that suit repair or like-for-like replacement. Move out towards Bexley, Sidcup, Bromley and Orpington and it's mostly interwar semis and post-war estates, where uPVC and aluminium casements are the usual choice. Conservation areas such as Greenwich and Blackheath Village can limit what you're allowed to fit on a street-facing elevation, so it's worth knowing which side of the line your property sits on before you start collecting quotes.

The businesses on this page are drawn from third-party business listings and ranked by public review rating and review count, with a small lift for those that show a working website and phone number. We read each business's homepage to confirm that window installation is what they primarily offer, which keeps unrelated trades off the page. Listings flagged as permanently closed are removed automatically. Where you see a Trust Verified badge, that business has additionally passed our full verification covering trade qualifications and accreditations, public liability insurance, trading history, customer review history and registered company information. Our How We Verify page sets out the full list. For any business without the badge, we haven't independently checked those things, so you'll need to do it yourself before you book.

Get at least three written quotes, and make sure each one specifies the same thing: frame material, glazing type (double or triple, with the U-value), handle and lock spec, and whether old windows are taken away. Ask whether the installer is registered with FENSA or CERTASS, because that's how replacement windows are signed off under the Building Regulations, and you should receive a certificate once the work is done. Check the guarantee in writing, ask how long the deposit is held and what it covers, and confirm they carry public liability insurance. A fitter who's vague about any of that is telling you something.

How We Select & Rate The Best Window Installers in South East London

Our ranking is driven by public review rating and review count taken from third-party business listings, with a small lift for businesses that have a working website and phone number. We read each business's homepage to confirm that window installation is what they primarily offer, and listings flagged as permanently closed are removed automatically. Businesses marked Trust Verified have additionally passed our full verification covering trade qualifications, insurance, trading history, customer review history and registered company information. Our How We Verify page has the full list. Other businesses on this page have not been independently verified by us, and inclusion is not an endorsement. Always do 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 →

Quick Comparison: Window Installers in South East London

#	Business	Rating	Reviews	Phone
1	SDG Windows Ltd	⭐ 4.8	212	020 8616 1516	View →
2	The London Sash Window Company	⭐ 4.9	147	020 8017 1632	View →
3	Sidcup Windows & Doors	⭐ 4.6	123	020 8298 9059	View →
4	Wandsworth Sash Windows	⭐ 4.7	61	020 7924 7303	View →
5	Crestshield Windows	⭐ 4.7	56	020 8776 5554	View →
6	Monsta Windows	⭐ 5.0	11	0208 473 1004	View →
7	Emmcon Glazing Ltd	⭐ 5.0	8	020 3623 4235	View →
8	The Window Clinic	⭐ 4.6	14	020 8771 2200	View →
9	Local Window Installer Erith	⭐ 5.0	6	0800 310 1665	View →
10	Diamond Glass & Glazing Southern Ltd	⭐ 5.0	2	07889 148746	View →
11	Sutton Windows - Welling	⭐ 4.1	10	0800 212289	View →
12	London and Surrey Windows	⭐ 4.1	8	020 8058 2765	View →

Our Top Picks

SDG Windows Ltd

Not Verified

★★★★★ 4.8 (212 reviews)

South East London 020 8616 1516

SDG Windows Ltd provides professional window installation services from their base on Sydenham Road in London SE26. The company has earned a strong reputation with local customers, maintaining a 4.8/5 star rating based on 207 verified Google reviews. They serve properties across London with reliable glazing solutions and expert fitting services.

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The London Sash Window Company

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★★★★★ 4.9 (147 reviews)

South East London 020 8017 1632

The London Sash Window Company specialises in sash window installation and restoration services throughout London. Based in SE20, the company has earned a 4.9/5 star rating from 147 verified customer reviews. They provide expert window installation services for both period properties and modern homes across the capital.

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Sidcup Windows & Doors

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★★★★★ 4.6 (123 reviews)

South East London 020 8298 9059

Sidcup Windows & Doors specialises in window installation services for residential and commercial properties in the Sidcup area and surrounding London boroughs. The company has earned a strong reputation with customers, maintaining a 4.6-star rating based on 123 verified Google reviews. Based on Westwood Lane in Sidcup, they serve the DA15 postcode area and neighbouring communities with professional window fitting solutions.

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Wandsworth Sash Windows

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★★★★★ 4.7 (61 reviews)

South East London 020 7924 7303

Wandsworth Sash Windows specialises in the installation and restoration of traditional sash windows across London, operating from their base in Lower Sydenham. The company has earned a strong reputation with a 4.7-star rating from 48 verified customer reviews. Their skilled craftsmen work throughout the capital, helping property owners maintain the period character of their homes while improving energy efficiency and security.

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Crestshield Windows

Not Verified

★★★★★ 4.7 (56 reviews)

South East London 020 8776 5554

Rated 4.9 out of 5, Crestshield Windows Ltd has built a consistent record among homeowners in south-east London. The company installs windows and doors for residential properties, operating from SE20. Customer feedback points repeatedly to clean installation work and clear communication throughout each job.

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Monsta Windows

Not Verified

★★★★★ 5.0 (11 reviews)

South East London 0208 473 1004

Monsta Windows is a window installation company based in London, serving residential customers across the capital. Operating from SE7, the business covers a broad stretch of south and east London, handling supply and fitting of replacement windows. Straightforward in scope, it offers a local alternative to the larger national installers that dominate the market.

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Emmcon Glazing Ltd

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★★★★★ 5.0 (8 reviews)

South East London 020 3623 4235

Calls to Emmcon Glazing Ltd often start with a leaking gutter, sagging fascia or water pooling near the roofline that's begun creeping into brickwork. The London firm replaces and repairs guttering, fascias and soffits, sorting out the cause rather than just the symptom. Its work across eight jobs has earned a full five-star record so far.

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The Window Clinic

Not Verified

★★★★★ 4.6 (14 reviews)

South East London 020 8771 2200

The Window Clinic is a window installation company operating in the SE25 area of South London. Rated 4.6 on Google across 14 reviews, it has built a steady local reputation for reliable fitting work. The clinic-style name reflects a focus on diagnosing and resolving glazing problems rather than simply selling new units.

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Local Window Installer Erith

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★★★★★ 5.0 (6 reviews)

South East London 0800 310 1665

Local Window Installer Erith provides professional window installation services from their base on Slade Green Road in Erith, serving the DA8 area and surrounding London districts. The company has earned a perfect 5-star rating from 6 verified customer reviews on Google. Customers can learn more about their services and request quotes through their dedicated website.

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Diamond Glass & Glazing Southern Ltd

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★★★★★ 5.0 (2 reviews)

South East London 07889 148746

Diamond Glass & Glazing Southern Ltd is a window installation company operating in London, covering the SE9 area and surrounding neighbourhoods. Specialising in residential and commercial glazing, the firm handles supply and fitting of windows and glass units. Its postcode base in SE9 places it well for projects across south-east London.

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Sutton Windows - Welling

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★★★★☆ 4.1 (10 reviews)

South East London 0800 212289

Sutton Windows - Welling provides professional window installation services from their base on Bellegrove Road in Welling, serving the DA16 area and surrounding London boroughs. The company maintains a solid 4-star rating from 9 verified customer reviews on Google, reflecting their reliable approach to residential and commercial glazing projects. Their experienced team handles various window types and installation requirements for local property owners.

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London and Surrey Windows

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★★★★☆ 4.1 (8 reviews)

South East London 020 8058 2765

London and Surrey Windows specialises in professional window installation services across London and Surrey from their base in SE19. The company has earned a 4.1/5 star rating from 8 verified customer reviews on Google. Their experienced team provides comprehensive window fitting solutions for residential and commercial properties throughout the region.

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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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Frequently Asked Questions

How much does a window installers cost in South East London?

For uPVC double glazing, expect roughly £350 to £700 per standard window, fitted, depending on size and style. A full house of eight to ten windows in a typical three-bed semi in Bexley or Sidcup often lands between £4,000 and £8,000. Aluminium costs more, usually £700 to £1,400 per window. Timber sash windows are the priciest, commonly £1,200 to £2,500 each for new double-glazed units, and restoration of existing sashes can run from £300 to £800 per window. Prices climb with bay windows, awkward access on upper floors and conservation area requirements. Get two or three quotes, as it's completely normal and you'll quickly see what's reasonable.

Do I need planning permission to replace my windows?

Usually not. Like-for-like replacement is normally permitted development for houses. Flats and maisonettes are different, as permitted development rights often don't apply, so check with your freeholder or lease. Conservation areas and listed buildings are the main trap. Parts of Greenwich, Blackheath, Lee and Bromley sit in conservation areas, and an Article 4 direction can remove your right to change street-facing windows without consent. A quick call to your borough planning team (Lewisham, Greenwich, Bromley, Bexley or Southwark) will settle it before you commit.

What's the difference between uPVC, aluminium and timber windows?

uPVC is the cheapest and lowest maintenance, and it suits most post-war and interwar homes. Aluminium has slimmer frames and a modern look, and it's popular on extensions and rear glazing, but it costs more. Timber is the right call for period properties, especially Victorian terraces in Deptford, Brockley and Blackheath, and it's often the only thing a conservation officer will accept. It needs repainting every five to eight years. Composite and timber-effect uPVC sit somewhere in between if you want the look without the upkeep.

How long does a window installation take?

Most installers fit a standard window in one to two hours, so an average house is typically done in one or two days. Made-to-measure frames take longer to arrive. Allow four to eight weeks from survey to fitting for uPVC, and up to twelve weeks or more for bespoke timber sashes. Expect some dust, and ask the installer to confirm in advance how they'll protect floors and what they'll do about making good plaster and decorating around the frames, because that's often not included.

Will I get a certificate for the new windows?

You should. Replacement windows must comply with the Building Regulations, and an installer registered with FENSA or CERTASS can self-certify the work and issue a certificate. Without one, you'd need to apply for building control sign-off, which costs more and is a hassle. Keep the certificate safe, as your conveyancer will ask for it when you sell. Ask before you book whether the installer is registered, and don't accept 'we'll sort it later'.

How do I check and choose between window installers?

Start with the paperwork. Ask for proof of FENSA or CERTASS registration and check it with the scheme itself. Ask for a copy of their public liability insurance and look at the dates and cover level. Read recent online reviews for patterns, especially around aftercare and snagging. Ask for addresses of recent jobs nearby and, if you can, go and look. Compare quotes line by line, as a cheap price often leaves out removal of old frames or making good. Get the guarantee, deposit terms and start date in writing, and never pay the full amount upfront. If a business isn't marked Trust Verified, we haven't independently checked any of this, so it's down to you.

12 Best Window Installers in South East London for 2026

Quick Comparison: Window Installers in South East London

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