Sliding doors for extensions and garden rooms across Greater London
A few practical points decide whether sliding doors for extensions suit a particular room and opening:
Planning an extension in Greater London? Send us the drawings before the steel is ordered, so the beam above the doors can be designed with the door in mind.
If your Greater London builder is about to pour the screed, confirm the finished floor level for the threshold first, because it is very hard to change afterwards.
- A check survey once the opening is built means the door is made to the real dimensions, accounting for any small variation in the brickwork or blockwork.
- Telling the engineer the door type and span early lets them design the beam above it to limit deflection, protecting the smooth running of large sliding panels.
- Setting the finished floor level before the screed goes down allows a low threshold, typically 15–25 mm, or a flush one with a drainage channel outside.
Guide prices for sliding doors for extensions in Greater London
The table shows guide prices for common sizes, supplied and fitted, including VAT. Your exact price is fixed in a written quote once the opening in your home has been measured.
| 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 |
| 3.0 m | 2 panels | £6,895–£8,395 |
| 6.0 m | 4 panels | £11,395–£13,895 |
Every size is on the sliding doors for extensions page.
Daylight and glass in Greater London
In Greater London the shortest day has roughly 7 h 50 min of daylight and the longest about 16 h 38 min. The noon sun sits near 15° above the horizon in winter and 62° in summer — so glass that faces south collects useful warmth from October to March, while a west-facing door may need solar control to stop it overheating in July.
Towns we cover in Greater London
We survey and fit sliding doors for extensions in 90 towns across Greater London, including the BR1, BR3, BR6, BR7, CR0, CR4 postcode districts.
Approvals in England
Doors in an English extension go through the extension's Building Regulations approval. Under Approved Document L, the total area of windows, roof windows and doors is normally capped at 25% of the extension's floor area plus any openings the extension removes, unless your designer shows compensating improvements; the glass must be safety glazing under Approved Document K.
Questions about sliding doors for extensions in Greater London
Can you match other doors and windows in my Greater London home?
Usually, yes. Most aluminium and uPVC systems come in standard RAL colours and finishes, and we can quote dual colour where the inside and outside need to differ. Bring photos of existing frames to the survey.
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.
Can you work with my builder and architect?
Yes, working with your builder, architect and structural engineer is the normal way we approach extension doors. We can provide technical details, opening sizes, threshold requirements and fixing information, and attend site for the check survey. Your builder forms the opening and prepares the floor, and our installers fit the doors to the agreed programme.
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.