- Postcode district
- N3
- Survey
- Free for new and replacement doors
- Typical lead time
- Typically 6–8 weeks for slimline systems after check survey sign-off
- Guide price
- From £5,095 inc VAT
- Nearby
- Hendon, Mill Hill, Golders Green
- Building rules
- England
Are sliding doors for extensions right for your Finchley home?
Before you settle on a door type, it helps to know what sliding doors for extensions do well and what to check before you order.
Where an extension in Finchley faces south or west, ask about solar-control glass, because a wall of glass in a single-storey room can overheat in summer.
Self-building in Finchley or elsewhere in Greater London? Ask for the sliding doors to be quoted as part of a wider glazing package so the frames, colours and glass match across the house.
- Slimline aluminium systems with interlocks typically around 20–25 mm maximise the glass in a new rear wall, keeping the view as open as possible.
- We provide the structural opening size and fitting tolerances in writing, giving your builder a clear target and avoiding disputes about who measured what.
- Being involved at drawing stage means the opening is formed to suit the door, rather than the door being compromised to suit an opening built a few centimetres out.
Daylight in Finchley and what it means for your glass
At the latitude of Finchley, the midday sun climbs to about 62° in late June but only about 15° in late December, when daylight lasts around 7 h 49 min against 16 h 39 min in midsummer. A south-facing sliding door for an extension lets that low winter sun deep into the room; on a west or south elevation, solar-control glass keeps summer afternoons comfortable.
How much do sliding doors for extensions cost in Finchley?
Guide prices are the same across Greater London. They cover the door supplied and fitted into a prepared opening, including VAT, with options itemised in your quote.
| Overall width | Typical panels | Guide price (fitted, inc VAT) |
|---|---|---|
| 1.8 m | 2 panels | £5,095–£6,195 |
| 2.1 m | 2 panels | £5,495–£6,795 |
| 2.4 m | 2 panels | £5,995–£7,295 |
See every size on the sliding doors for extensions page or try the guide price tool.
Timescales for sliding doors for extensions in Finchley
Here is the usual sequence in Finchley: guide price, free survey, written quote, any building work, then manufacture (typically 6–8 weeks for slimline systems after check survey sign-off). Fitting typically takes 1–2 days, scheduled to the build programme. Nearby, we also survey in Hendon, Mill Hill and Golders Green.
Rules for sliding doors for extensions in England
In England, sliding doors in a new extension are covered by the extension's own Building Regulations application rather than a separate door notification. Approved Document L limits the glazed area: windows, roof windows and doors should not normally exceed 25% of the extension's floor area plus the area of any windows or doors lost to the extension, unless the extra glass is compensated for elsewhere. The doors must also meet the energy and safety glazing standards.
Choosing the specification
- Solar-control glass. Coated glass for south- and west-facing extensions prone to summer overheating.
- Two-panel slimline. One sliding and one fixed panel, suiting openings up to around 3.6 m depending on the system.
- Triple glazing. For low-energy extensions or north-facing walls, subject to panel size limits.
Questions about sliding doors for extensions in Finchley
How soon can you survey in Finchley?
Surveys in the N3 district are booked at a time that suits you, and we offer survey dates when we reply to your enquiry. After you approve the written quote, manufacture is typically 6–8 weeks for slimline systems after check survey sign-off.
Why does the steel beam matter for sliding doors?
The steel beam above an extension's sliding door matters because every beam bends a little under load, and a large sliding door needs a straight, level head to run freely. If the engineer knows a wide slider will sit under the beam, they can design for low deflection. Too much movement can make panels stiff or bind.
What structural opening size should my builder leave for sliding doors?
Your builder should leave the structural opening size we give in writing for your chosen door, which is the frame size plus a small fitting tolerance on each side and at the head. The exact figure depends on the system and the threshold detail. We confirm it from your drawings early, then check the built opening before the door is made.
How much do sliding doors for an extension cost?
Slimline sliding doors for an extension have a guide price of £7,795–£9,495 for a 3.6 m opening and £9,595–£11,695 for a 4.8 m opening, fitted, inc VAT at standard 2.1 m height. Taller doors, extra panels, special glass and flush thresholds move the price. Your written quote after the check survey fixes it.