Two panels, one sliding
The simplest layout and the best value. One panel parks behind the fixed one, so the clear opening is about half the width.
Aluminium · Lift & slide
Big glass that still closes like a vault.
Lift & slide doors carry very large panels on rollers, then lower them onto compressed gaskets when closed. You get a wide, slim-framed opening that stays airtight and quiet. We draw it with you, make it to order and fit it with our own team.
The data on this page is for aluminium. Lift & slide is also available in timber and PVC for smaller openings. Compare materials.
- Panel weightup to 400 kg
- Panel heightup to 3,200 mm
- Panel widthup to 3,300 mm
- Interlock sightlinefrom c. 50 mm
- Thresholdflush or ≤15 mm
- Whole-door Uwfrom c. 0.9 W/m²K
Indicative System-class envelope. Certified values are published with each system data sheet.
Choosing a system
Lift & slide, inline slider or bi-fold?
All three can work in a London extension. They differ in panel size, how much frame you see, how well they seal and how they feel to use every day. This is the comparison we talk clients through at Stage 2.
| Lift & slide | Inline sliding | Bi-fold | |
|---|---|---|---|
| Largest panel | Very largeUp to c. 400 kg and 3.2 m tall | LargeUsually lighter hardware classes | SmallPanels typically ≤1.2 m wide |
| Frame you see when closed | One slim interlock per meeting | Very slim on minimal systems | A vertical frame every metre or so |
| Airtightness & weather | ExcellentPanel drops onto compressed gaskets | GoodMostly brush seals | GoodMany joints to seal |
| Clear opening | 50–67% of the widthNear 100% with a pocket | 50–67% | Up to c. 90% |
| Everyday use | Turn the handle, then the panel glides | Push to slide | Unfold every panel |
| Best for | Wide garden elevations, big glass, exposed sites | Contemporary minimal frames, moderate sizes | Opening the whole wall in summer |
How it works
A half-turn of the handle does the heavy lifting.
Closed and lowered
The panel sits down on its gaskets. Its own weight compresses them, which is why lift & slide doors seal so well against wind, rain and noise.
Turn the handle 180°
A gear in the sash lifts the panel a few millimetres onto steel rollers. The gaskets come clear of the frame.
Slide and park
The panel glides on the rollers with a light push. You can leave it at any position, and a soft-close damper is an option.
Configurations
Six layouts cover almost every opening.
Plan views. Accent lines are sliding panels; grey lines are fixed. We pick the layout from your opening width, the panel weight and where you want the door to park.
Three panels, three tracks
Two panels stack behind one fixed panel and open two-thirds of the width. Good when one side must stay clear.
Four panels, centre opening
The classic garden elevation: symmetrical, and the two middle panels part to the sides. It keeps panel weights down on wide openings.
Six panels, centre opening
For openings over about 7 m. Four panels slide on three tracks and two-thirds of the width opens.
Corner, no post
Two sliding panels meet at a corner with no post, so the garden corner opens completely. The structure must carry the corner load instead: we coordinate this with your engineer at Stage 3.
The panels slide into a pocket in the wall, leaving the full width open and no frame in view. This needs a cavity designed for it, so it must be decided by Stage 3.
Sizing tool
Check panel size and weight before you draw it.
Enter the structural opening. The tool estimates panel width, glass weight, clear opening and handling needs, and flags the Approved Document L 25% rule for extensions. These are planning figures. We confirm the final numbers on project drawings.
- Panel width
- —
- Approx. panel weight
- —
- Approx. clear opening
- —
- Opening area
- —
Performance
Design envelope
The ranges a lift & slide system of this class achieves. On every project we issue the certified values for the exact system, size and glass, so you can quote them in your specification and your Part L calculation.
Indicative We'll replace each range with the certified value and its test reference once the system data sheet is published.
| Thermal transmittance, whole door (Uw) | c. 0.9–1.4 W/m²KTriple vs double glazing and size. Approved Document L limiting values: 1.4 for replacement doors in existing homes; 1.6 in new dwellings. |
|---|---|
| Maximum panel weight | 300 kg standard / 400 kg heavy-dutySet by the roller and gear hardware class. |
| Maximum panel size | c. 3,300 × 3,200 mmLarger on engineering review. |
| Interlock sightline | from c. 50 mmSlim interlock option. |
| Frame depth | c. 160–220 mm2 or 3 tracks. |
| Threshold | Flush (recessed) or low upstand ≤15 mmA ≤15 mm upstand meets the accessible-threshold expectation in Approved Document M. |
| Security | Specified to PAS 24:2022Needed for doors in new dwellings under Approved Document Q. |
| Weather (BS 6375-1 / EN 12207, 12208, 12210) | Classified per system test reportWe match the classes to your site's exposure. |
| Acoustic (Rw) | up to c. 40 dBWith asymmetric laminated acoustic glass. |
| Safety glazing | Toughened or laminated throughoutDoors and side panels are critical locations under Approved Document K. |
Thresholds
A flush threshold is a floor detail, not a door option.
Getting inside and outside onto one level is the reason most clients choose lift & slide. It only works if the slab, insulation and drainage are drawn for it.
- The slab needs a recess of the depth the system needs. We give you that dimension at Stage 3.
- The thermal line has to run under the frame to avoid a cold bridge, so coordinate it with the insulation and any underfloor heating.
- Outside, fit a linear drain and lay the paving to fall away. On exposed sites, a low upstand may be the safer choice.
- For Part M, keep any upstand to 15 mm or less.
Glass, finish, hardware
Specified once, built exactly as drawn.
Every component on your specification is the one we install. If a change is ever needed, we tell you in writing and show its effect on performance and certification before anything is ordered.
Glass
Double or triple
Low-E, warm-edge spacers, argon fill. Options: solar control for south and west elevations (relevant to Part O), acoustic laminated glass near main roads and under flight paths, and laminated security glass.
Finish
Any RAL, dual colour
Polyester powder coat to a recognised architectural standard, textured or matt finishes, and anodised options. Different colours inside and out are available at no structural penalty.
Hardware
Lift gear and rollers
Branded lift-and-slide hardware sized to the panel weight. Choose slim, flush or lockable handles, multi-point locking and soft-close dampers.
Extras
Motorised and screened
Concealed motorisation for very large panels, integrated insect screens and child-safety locks.
Designing in London
Four things that decide whether a big slider works.
Most problems with large sliding doors start long before installation. These are the four we check on every set of drawings. The design guide covers each one in detail.
01 · Structure
Beam deflection
A sliding head tolerates only a few millimetres of movement. Your engineer should design the beam to the system limit, not just to a general span ratio.
02 · Floor
Recess and drainage
A flush threshold needs a formed recess, a continuous thermal line and a drain outside. All three must be fixed before the slab is poured.
03 · Access
Getting the glass in
A 300 kg panel won't go through a Victorian hallway. We plan the route from kerb to opening at survey, and that can mean a crane licence.
04 · Regulations
Part L, O, K, Q
Glazing over 25% of the extension floor area needs SAP. New homes need an overheating check, safety glass and PAS 24 security.
Working with us
What you get at each RIBA stage.
We work as part of the design team rather than as a supplier who shows up at tender. Each stage ends with something you can use.
Stage 2 · Concept
Configuration and panel-size advice, a budget range and a check on structure and access.
→ budget ±15%Stage 3 · Spatial
System recommendation, typical head, sill, jamb and threshold details, and the deflection limit for your engineer.
→ DWG detailsStage 4 · Technical
Project shop drawings, certified U-values for your sizes, loads on the structure and a fixed quotation.
→ drawings to sign offStage 5 · Site
Site survey, manufacture to signed drawings, delivery plan and installation by our own team.
→ installed & testedStage 6 · Handover
O&M manual, declarations of performance, the guarantee, and a check-in visit after the first season.
→ handover pack
Technical files
Lift & slide spec pack
One download with everything you need to specify the door. We'll publish it when the system data sheet is certified. Until then, request it and we'll send the current drafts for your project.
| File | Format | Status |
|---|---|---|
| Head, sill, jamb & interlock details | DWG · PDF | Preparing |
| Flush & low threshold details | DWG · PDF | Preparing |
| BIM object | RVT · IFC | Preparing |
| NBS-style specification clause | DOCX | Preparing |
| Data sheet & declaration of performance | Preparing | |
| Installation & maintenance guide | Preparing |
Questions
Lift & slide FAQ
How wide can a lift & slide door be?
There's no practical limit on overall width; it's a question of how many panels you use. Each panel is limited by weight (typically up to 400 kg) and size (around 3.3 m wide). Wide openings use four or six panels. Use the sizing tool for a first check.
Is a 300 kg panel hard to open?
No. Once lifted onto its rollers the panel needs only a light, steady push. The handle's gear does the lifting. For very large panels we offer concealed motorisation.
Lift & slide or bi-fold for a London extension?
Bi-folds open nearly the whole width, but you see a frame every metre or so when they're closed, and that's most of the year. Lift & slide gives bigger glass, slimmer sightlines and better sealing, with half to two-thirds of the width opening. See the comparison.
Can I have a completely flush threshold?
Yes, if the floor is designed for it: a recess in the slab, a continuous thermal line and drainage outside. On exposed or high sites, a low upstand of 15 mm or less is often the more robust choice and still meets Part M.
Will it meet Building Regulations?
For an extension, the door's U-value needs to meet the limiting value in Approved Document L, and the total glazing should stay within 25% of the extension floor area for the simple route. Above that, your energy assessor uses SAP. New dwellings also need PAS 24 security (Part Q), safety glazing (Part K) and an overheating assessment (Part O). We provide the data for each.
Do I need planning permission?
Many rear extensions fall under permitted development, but not in conservation areas where Article 4 directions apply, and not for listed buildings. Planning is your architect's call. We can supply elevations and sightline drawings for the application.
Who makes and installs the doors?
We make them to order on a branded system and install them with our own team. We don't subcontract fitting. You get one project manager from survey to handover.
You're a new company. Why should we trust you with a big opening?
That's a fair question. The answer is in what you can check: certified system data, a full-size sample before you order, written change control, our own installers and a guarantee from a UK company. Read how our founding projects work.