FAQ
Everything you need to know about double glazing windows and doors — answered by Ada Windows Ltd, FENSA-registered manufacturers and installers based in Enfield, North London.
About Ada Windows
Is Ada Windows FENSA registered?
Yes. Ada Windows Ltd is a FENSA-registered installer (registration number 36583). FENSA — the Fenestration Self-Assessment scheme — is a government-authorised body that ensures all window and door replacement installations comply with UK Building Regulations, in particular Part L (energy efficiency) and Part N (safety glazing). Every Ada Windows installation is registered with FENSA, and customers receive an official FENSA certificate on completion. This certificate is required when selling your home and proves the installation meets building regulations without the need for a separate building control inspection.
FENSA registration is one of the most important indicators of a reputable double glazing company. It means Ada Windows is regularly audited and can only retain registration by maintaining installation standards.
Does Ada Windows manufacture its own windows and doors?
Yes. Ada Windows operates its own production factory in Enfield, North London, where it fabricates UPVC and aluminium windows and doors in-house. The company has been manufacturing its own products since 2015. This is relatively uncommon among local double glazing companies — most installers source finished products from a third-party manufacturer.
Because Ada Windows controls its own fabrication, it can offer a wider range of configurations, colours, and bespoke sizing than companies that rely on off-the-shelf supply. Quality is managed end-to-end, from raw profile to finished installation.
How long has Ada Windows been in business?
Ada Windows Ltd was established as a manufacturing and installation company in 2015, with its factory based in Enfield. The management team has experience in the double glazing industry stretching back to 2001. Since beginning manufacture in 2015, Ada Windows has completed over 4,000 installation projects and currently installs up to 2,400 windows per year across London and the surrounding counties.
What accreditations does Ada Windows hold?
Ada Windows Ltd holds six industry accreditations and consumer protection registrations:
FENSA (registration 36583) — government-authorised self-certification for Building Regulations compliance on all window and door replacements.
Trustmark (registration 1461244) — government-endorsed quality scheme verifying technical competence, customer service, and fair trading practices.
HomePro — consumer protection scheme providing deposit protection and insurance-backed guarantees independent of the installer.
Fairtrades — accreditation for ethical and transparent trading practices.
BFRC — British Fenestration Rating Council energy performance ratings on all Ada Windows products.
CE Marking — product safety certification confirming compliance with UK and EU requirements.
Is Ada Windows Trustmark registered?
Yes. Ada Windows Ltd is registered with Trustmark (registration number 1461244). Trustmark is the government-endorsed quality scheme administered by the Department for Energy Security and Net Zero. It independently vets businesses for technical competence, customer service standards, and business practices. Trustmark registration is also a condition of accessing certain government energy-efficiency grant schemes, including the Great British Insulation Scheme.
Where is Ada Windows based?
Ada Windows Ltd is based in Enfield, North London, where its production factory and headquarters are located. Enfield is the primary service area. The company covers Greater London and the surrounding Home Counties — Hertfordshire, Essex, Kent, and Surrey — within a 50-mile radius. Larger commercial projects are considered up to a 100-mile radius. Call 020 8803 8004 to confirm availability for your area.
Windows and doors
What types of windows does Ada Windows install?
Ada Windows manufactures and installs UPVC and aluminium windows in the following styles:
Casement windows — the most popular style in the UK; hinged on one side, available as single or double casement.
Tilt and turn windows — tilt inward at the top for ventilation, or open fully inward for easy cleaning; ideal for flats and upper floors.
Flush sash windows — a modern style where the sash sits flush with the outer frame, giving a clean contemporary profile.
Sliding sash windows — a classic vertical sliding design that suits period and Victorian properties.
Bay windows — three or more window panels set at angles to project outward from the wall.
All window styles are available in double or triple glazing and in a full range of frame colours.
What types of doors does Ada Windows supply and install?
Ada Windows manufactures and installs the following door types:
UPVC doors — durable, low-maintenance front and back doors with multi-point locking.
Composite doors — GRP (glass reinforced plastic) outer skin over a solid foam core; combines the appearance of timber with superior insulation and security.
Aluminium doors — slim, modern frames available in a full RAL colour range; suited to contemporary properties and commercial buildings.
Bifold doors — folding-sliding door systems that open the full width of the aperture; available in UPVC and aluminium.
Sliding patio doors — space-saving large glazed panels that slide on a track; available in UPVC and aluminium.
All doors include multi-point locking systems and toughened or laminated safety glass as standard.
What is the difference between UPVC and aluminium windows?
UPVC (unplasticised polyvinyl chloride) and aluminium are the two main frame materials used in modern double glazing. Here is how they compare:
Cost: UPVC is generally less expensive than aluminium for equivalent window sizes. Aluminium commands a premium due to its material properties and slimmer sightlines.
Appearance: UPVC frames are bulkier in profile. Aluminium allows slimmer sightlines and a more contemporary, minimal look — particularly suited to large glazed areas, bifold doors, and modern architecture.
Colour: Both materials are available in a wide colour range. UPVC is typically available in foiled finishes such as white, anthracite grey, black, rosewood, and golden oak. Aluminium is powder-coated and available in virtually any RAL colour.
Maintenance: Both materials are low-maintenance and do not require painting. UPVC can yellow slightly over decades in strong sunlight, though modern profiles are highly UV-resistant. Aluminium does not discolour.
Thermal performance: Both achieve excellent energy ratings when fitted with quality glazing units. Modern thermally broken aluminium frames are as thermally efficient as UPVC.
Ada Windows manufactures both UPVC and aluminium products at its Enfield factory and can advise on the best choice for your property during a free site survey.
What is the difference between double glazing and triple glazing?
Double glazing consists of two panes of glass sealed around a cavity, typically 16–20mm wide, usually filled with argon gas. The cavity and gas filling significantly reduce heat loss compared to single glazing.
Triple glazing adds a third pane and a second cavity, further reducing heat loss and improving acoustic insulation. It is heavier than double glazing and more expensive, but offers measurably better thermal performance — typically a U-value of around 0.6–0.8 W/m²K compared to 1.0–1.2 for quality double glazing.
Triple glazing is most beneficial in properties with high heating costs, on particularly exposed elevations, or in rooms where noise reduction is a priority. For most UK homes, A-rated double glazing provides excellent value. Ada Windows supplies both double and triple glazed units and can advise during your survey.
What is secondary glazing and when should I use it?
Secondary glazing is an additional internal glazed panel fitted inside the existing window reveal, without removing or altering the original window. It is not the same as double glazing — it is a separate inner layer added to a window that already exists.
Secondary glazing is the appropriate solution when:
The property is a listed building or in a conservation area where planning conditions prevent changing the external windows.
The original windows are timber sash or other heritage frames that the owner wishes to retain.
The property is rented and the landlord does not wish to replace the windows.
Budget does not stretch to full window replacement but thermal or acoustic improvement is needed.
Secondary glazing from Ada Windows significantly reduces heat loss and can cut noise transmission by up to 80% in some configurations. It does not require planning permission in most cases, though Ada Windows recommends checking with your local planning authority for listed or conservation area properties.
What glazing options are available?
Ada Windows offers the following glazing specifications within its window and door units:
Standard double glazing — two panes with argon-filled cavity; meets Building Regulations energy requirements.
A-rated energy-efficient double glazing — enhanced low-emissivity (Low-E) coating on the inner pane; BFRC A-rated.
Triple glazing — three panes with two argon-filled cavities; superior thermal and acoustic performance.
Acoustic glazing — laminated glass with acoustic interlayer; significantly reduces external noise; recommended for properties on busy roads, near railways, or under flight paths.
Obscure glass — various patterns (Satin, Stippolyte, Flemish, Cotswold, and others) for privacy in bathrooms, cloakrooms, and side panels.
Safety glass — toughened or laminated glass meeting BS EN 12600 requirements; required by Building Regulations in certain positions (low-level panes, doors, and side panels).
Decorative glass — leaded, Georgian bar, and stained effects available on selected products.
What colours and finishes are available?
UPVC windows and doors are available in the following standard foiled finishes: White (classic), Anthracite Grey, Black, Rosewood, Mahogany, Golden Oak, and Cream. Dual-colour options are available — for example, white internally with anthracite grey externally.
Aluminium windows and doors are powder-coated and available in virtually any RAL colour. Popular choices include Anthracite Grey (RAL 7016), Jet Black (RAL 9005), Traffic White (RAL 9016), Signal Grey (RAL 7004), and Bronze. Custom RAL colours are available to order.
Hardware — handles, hinges, and locking mechanisms — is available in a range of finishes including white, chrome, gold, black, and anthracite.
Installation and process
How does the Ada Windows installation process work?
The Ada Windows process from first contact to completed installation follows these steps:
- Free site survey — a fenestration surveyor visits your property to take precise measurements, assess the existing frames and reveals, discuss your requirements and preferences, and provide a written quotation. There is no charge for this.
- Quotation and order — once you are happy with the quotation, a deposit is taken and your order is placed with the Ada Windows factory in Enfield.
- Manufacturing — your windows and doors are fabricated to your exact measurements and specifications at the Enfield factory.
- Installation — Ada Windows installation teams fit your windows and doors, make good around the reveals, and remove all waste and packaging.
- FENSA registration — all installations are registered with FENSA. Your FENSA certificate is issued after installation, usually within a few weeks.
- 10-year guarantee — your insurance-backed guarantee documentation is issued covering both labour and workmanship.
How long does installation take?
The length of an installation depends on the number of windows and doors being fitted and the complexity of the property. As a general guide:
A single window replacement typically takes two to four hours.
A full house of eight to twelve windows and one or two doors is usually completed within one to two days.
Larger properties or those with non-standard apertures may require additional time.
Ada Windows will confirm the expected duration at the survey stage and give you a scheduled installation date once your order is in production.
Do I need scaffolding for window installation?
In most cases, no. Ada Windows installation teams are equipped to work from ladders for standard first and second floor windows. Scaffolding is not usually required for typical two-storey residential properties.
For higher floors, certain loft conversions, or where safe ladder access is not possible, temporary scaffolding or a mobile elevated work platform (MEWP) may be required. Ada Windows will assess access requirements at the site survey stage and advise accordingly. Any scaffolding costs would be discussed and agreed as part of the quotation.
Will installation make a mess inside my home?
Ada Windows installation teams work to minimise disruption and protect your home throughout the installation process. Dust sheets are used to protect floors and furnishings near the work area. All old frames, glazing units, and packaging are removed and taken away at the end of the job.
Some dust and debris around the window reveals is inevitable during removal of old frames, particularly in older properties. Ada Windows teams clean up all work areas on completion. Most customers find the disruption minimal, particularly compared to other home improvement work.
Do I need planning permission to replace my windows?
In most cases, replacing windows and doors in England is permitted development and does not require planning permission, as long as the new windows are similar in appearance to those being replaced.
However, planning permission or listed building consent may be required in the following situations:
The property is a listed building — any alteration, including window replacement, requires listed building consent.
The property is in a conservation area — permitted development rights are restricted; you may need conservation area consent for changes to the front elevation.
The property has a planning condition removing permitted development rights — this may apply to some newer-build estates.
Ada Windows recommends checking with your local planning authority before proceeding if any of the above may apply. For properties in conservation areas, Ada Windows can advise on appropriate window styles and materials, including secondary glazing as an alternative where full replacement is restricted.
What guarantee does Ada Windows provide?
Ada Windows provides a 10-year insurance-backed guarantee (IBG) on all window and door installations. This covers both labour and workmanship.
The guarantee is insurance-backed, meaning it is underwritten by an independent insurer and remains valid even if Ada Windows ceases to trade. This is an important distinction from a standard company guarantee, which would become worthless if the company closed.
The glazing units themselves (the sealed double or triple glazed unit) carry a separate manufacturer’s guarantee against failure of the seal, which would result in condensation between the panes.
Energy efficiency
How much can new double glazing reduce my energy bills?
The Energy Saving Trust estimates that replacing single glazing with A-rated double glazing can save a typical semi-detached home in England around £110–£135 per year on heating bills. Savings vary depending on the size of the property, the number of windows, the existing glazing, and how well-insulated the rest of the property is.
The biggest savings come when replacing very old double glazing (pre-2002) or single glazing. If your existing double glazing is already relatively modern and energy-efficient, the saving from replacement will be smaller.
Beyond energy costs, new double glazing improves comfort significantly — reducing cold spots near windows, eliminating draughts, and reducing condensation on the inner pane.
What does an A energy rating mean for windows?
The British Fenestration Rating Council (BFRC) Window Energy Rating (WER) system rates windows from A++ (most efficient) to G (least efficient), using a scale similar to domestic appliances.
The rating takes into account three factors: the U-value (heat loss through the frame and glass), the g-value (solar heat gain through the glass), and the air leakage rate.
An A-rated window provides the best balance of low heat loss and useful solar gain. Building Regulations in England require replacement windows to achieve a minimum WER of C, though A-rated windows are strongly recommended for the best thermal performance and lowest energy bills.
All Ada Windows products are BFRC-rated and carry energy labels. A-rated windows and above are available across the UPVC and aluminium ranges.
Does Ada Windows use recycled materials?
Yes. Ada Windows uses recycled UPVC material in the manufacture of window frames, reducing the volume of virgin PVC required in production. UPVC is a recyclable material that can be reprocessed multiple times without significant degradation.
Ada Windows also operates a waste recycling scheme for both factory offcuts and materials removed during installation. UPVC frame offcuts, aluminium profiles, and insulated glazing units removed from properties are segregated and recycled rather than sent to landfill.
This commitment to recycling is part of Ada Windows’ approach to responsible manufacturing within the double glazing industry.
Finance and cost
How much does double glazing cost in London?
The cost of double glazing in London depends on the number of windows, the frame material (UPVC or aluminium), the glazing specification, and the style of window or door. As a general guide for the London market in 2025–2026:
A standard UPVC casement window replacement (supply and installation) typically costs £400–£900 depending on size.
Aluminium windows cost more than UPVC equivalents, typically 20–40% more for a comparable specification.
A full house of ten to twelve standard-sized UPVC windows might cost £4,500–£9,000 installed, depending on specification and property specifics.
Bifold doors and sliding patio doors are priced per panel; a four-panel bifold door set typically costs £2,500–£5,000 installed.
These are indicative figures only. The most accurate way to get a price for your property is to request a free site survey and written quotation from Ada Windows, which carries no obligation.
Does Ada Windows offer finance?
Yes. Ada Windows offers finance options on window and door installation projects, subject to status. Finance allows you to spread the cost of your installation over a period of time rather than paying in full upfront.
Ada Windows Limited is an introducer appointed representative of Ideal Sales Solutions Ltd, trading as Ideal4Finance. Ideal Sales Solutions is a credit broker and not a lender (FRN 703401). Finance is available subject to status. The rate offered is provisional and will depend on your personal circumstances, the loan amount, and term.
To find out more about finance options, call Ada Windows on 020 8803 8004 or visit adawindows.com/finance.
Is a deposit required to place an order?
Yes. A deposit is taken when you confirm your order with Ada Windows. The deposit secures your order into production at the Enfield factory.
Ada Windows is registered with HomePro, which provides independent deposit protection. This means your deposit is protected even in the unlikely event that Ada Windows is unable to complete the installation. HomePro also backs the 10-year installation guarantee.
Repairs and aftercare
My existing double glazing has condensation between the panes. Can Ada Windows help?
Condensation between the panes of a double-glazed unit means the sealed unit has failed — the hermetic seal around the edge of the unit has broken down, allowing moist air to enter the cavity. This is sometimes called ‘blown’ or ‘misted’ double glazing.
In most cases this is remedied by replacing the glazed unit (the glass) rather than the entire window frame, which is a much less expensive repair. Ada Windows can assess the condition of your existing frames and advise whether unit replacement or full window replacement is the more appropriate and cost-effective solution.
If your windows are still within a guarantee period, you should first check whether the failure is covered by the original installer’s guarantee or the glazing unit manufacturer’s guarantee.
Can Ada Windows repair existing windows and doors rather than replacing them?
Ada Windows primarily focuses on the supply, manufacture, and installation of new windows and doors. For minor repairs — such as replacing a failed glazing unit, repairing a broken handle or lock mechanism, or adjusting a door that is not closing correctly — Ada Windows can advise during a survey visit whether repair or replacement is the more practical and economical option.
In many cases where frames are still sound and in good condition, replacing only the sealed glazing units is a cost-effective way to restore thermal performance and eliminate condensation.
Getting a quote
How do I get a quote from Ada Windows?
Getting a free, no-obligation quotation from Ada Windows is straightforward:
By phone — call 020 8803 8004 during office hours to speak with the Ada Windows team and arrange a survey.
Online — use the quote request form at adawindows.com/contact to send your details and a member of the team will be in touch.
A fenestration surveyor will visit your property to take measurements, discuss your requirements, and provide a written quotation. There is no charge for the survey or the quotation, and there is no obligation to proceed.
What areas does Ada Windows cover?
Ada Windows covers all London boroughs — North, East, West, Central, and South London — plus Hertfordshire, Essex, Kent, and Surrey within a 50-mile radius of the Enfield factory. Larger commercial projects are considered up to a 100-mile radius.
The primary service area is North London, including Enfield (where the factory is based), Haringey, Barnet, Islington, Hackney, Waltham Forest, and Camden. South London installations are available subject to location — call 020 8803 8004 to confirm availability before booking a survey for South London addresses.
Ada Windows serves both residential and commercial clients across all covered areas.
Ready to get started? Call Ada Windows on 020 8803 8004 or visit adawindows.com/contact for a free, no-obligation survey and quotation. Ada Windows Ltd — FENSA registered (36583) · Trustmark registered (1461244) · 10-year insurance-backed guarantee · Manufactured in Enfield, North London.
