Bifold vs Sliding Doors: Costs, Pros and Cons (2026)
If you are opening the back of your home into the garden, the glazing you choose will define how the whole space feels, and the decision almost always comes down to bifold vs sliding doors. Both flood a kitchen or rear extension with light, but they behave very differently, they are not the same price, and the right answer depends on the width of your opening and how you actually live. This guide gives you a straight comparison, 2026 UK costs by material and size, the numbers that matter (opening percentages, sightlines, thresholds, U-values) and a decision checklist at the end.
The quick answer
- Choose bifold doors if you want to open up the entire span and connect inside and out completely in summer, or if the opening is narrower than about four metres.
- Choose sliding doors if you want the biggest possible glass and the clearest view when the doors are closed, which is most of the year, or if the opening is five metres or wider.
- On a standard opening, sliding doors are usually cheaper; on a premium, very wide opening, sliders can cost more than bifolds.
At a glance
| Feature | Bifold doors | Sliding doors |
|---|---|---|
| Installed cost, aluminium (standard opening) | £3,000 – £7,500 | £1,800 – £4,500 (standard); £5,000 – £12,000+ (slimline / large) |
| Clear opening when fully open | Around 90% of the span | 50 – 66% of the span |
| Sightline between panels | Around 100 – 130 mm | Around 20 – 35 mm interlock |
| Maximum panel width | Around 1.2 m per panel | 2.5 – 3 m per pane |
| View when closed | Good, broken by frames | Best in class |
| Threshold | Flush or weathered (15 – 20 mm) | Flush or weathered (15 – 20 mm) |
| Thermal performance (double glazed) | U 1.2 – 1.6 W/m²K | U 1.2 – 1.6 W/m²K |
| Security | PAS 24 available | PAS 24 available |
| Space needed | Panels stack inside or outside | None; panels slide in-plane |
| Best for | Full garden connection, openings under 4 m | Light, views, openings over 5 m |
How they work
Bifold doors are a run of panels hinged together that concertina and fold back against the wall. A typical run is three to seven panels, each up to about 1.2 metres wide. Most are top-hung, which keeps the weight off the bottom track, or bottom-rolling, which suits very heavy sets. Almost every set includes a traffic door: one panel that opens on its own like a normal door, so you do not have to fold the whole run to let the dog out.
Sliding doors run on a track and slide behind one another. Standard inline sliders have two to four panes and always leave at least one pane in place. Lift-and-slide systems lift the pane a few millimetres off its seal before it moves, which gives a better seal and lighter action for big, heavy panes. Slimline or minimal-frame sliders push the interlock down to around 20 mm for the cleanest possible look, at a premium price.
Bifold doors cost (2026)
Prices below are supplied and fitted into a prepared opening, excluding the structural work to create it.
| Material | 3 panels (approx. 2.4 – 3 m) | 4 panels (3 – 4 m) | 5 panels (4 – 5 m) |
|---|---|---|---|
| uPVC | £2,000 – £3,000 | £2,600 – £3,700 | £3,200 – £4,200 |
| Timber (hardwood) | £2,200 – £3,400 | £2,900 – £4,000 | £3,500 – £4,800 |
| Aluminium | £3,150 – £4,800 | £4,000 – £6,000 | £5,000 – £7,200 |
A useful rule of thumb is £1,000 to £1,600 per panel installed for aluminium, or roughly £2,000 to £3,500 per square metre of glazed opening. Labour is typically £600 for a three-panel set, £800 for four and £1,000 for five, over one to two days. Very large or heavy sets sometimes need a small crane or lifting equipment at £250 to £500.
Sliding doors cost (2026)
| System | 2 panes (2 – 3 m) | 3 panes (3 – 4.5 m) | 4 panes (4.5 – 6 m) |
|---|---|---|---|
| uPVC inline | £1,500 – £2,500 | £2,200 – £3,200 | £3,000 – £4,000 |
| Aluminium inline | £1,800 – £3,200 | £2,800 – £4,500 | £4,000 – £6,000 |
| Aluminium slimline / lift-and-slide | £4,500 – £7,000 | £6,000 – £9,000 | £8,000 – £12,000+ |
Labour runs £600 to £1,500 depending on pane size and weight; a single three-metre pane can weigh well over 100 kg and needs several people or a lifter.
Extra costs that apply to both
The doors are only part of the bill. If you are creating a new opening or widening an existing one, budget for:
- Steel lintel or beam to carry the wall above: £800 to £2,500 supplied and fitted, plus £250 to £450 for the engineer's design
- Knocking through and making good: £1,000 to £3,000
- Building control for the structural work and the glazing: £150 to £400 for a replacement, more as part of an extension application
- Flush threshold drainage channel: £200 to £600
- Integral blinds between the glass panes: £300 to £600 per panel
- Blinds or curtains for a full-width opening: often overlooked, rarely cheap
When the doors are fitted as part of an extension, all of this is folded into the build. Our guide to house extension costs shows where glazing sits in the bigger picture.
So which is cheaper?
For a standard opening of three to four metres, sliding doors are usually the cheaper option: a two or three-pane aluminium slider at £1,800 to £4,500 against an aluminium bifold at £3,000 to £7,500. That is simply fewer components and less labour.
For a premium or very wide opening, the picture flips. Slimline sliders with 20 mm interlocks and panes three metres wide use thick, heavy glass and precision hardware, and cost £5,000 to £12,000 or more, which is above most bifold sets. If you are being quoted more for sliders than bifolds, that is why.
Light, views and sightlines
When the doors are shut, and they will be for most of the year, sliding doors win. Two or three panes with interlocks of 20 to 35 mm mean the opening is almost all glass. Bifolds have a frame of roughly 100 to 130 mm between every panel, so a five-panel set has four vertical bars breaking up the view. Slimline aluminium bifolds narrow that gap, but they cannot match a slider.
Opening up to the garden
This is where bifolds pull ahead decisively. Folded back, they clear around 90 per cent of the span, giving you a genuinely open wall for summer entertaining and a true indoor-outdoor feel. A sliding door always leaves at least one pane in place, so a two-pane slider opens 50 per cent of the span and a three-pane slider around 66 per cent. If throwing the whole wall open is the dream, bifolds are the answer.
Space and layout
Bifold panels stack at one or both ends of the opening, inside or outside, and that stack takes up 300 to 600 mm of wall space that you cannot put furniture against. Sliding panels stay within the plane of the opening, which matters in a tight kitchen where every wall counts. On openings under about four metres, a three-panel bifold is compact enough that this rarely matters; on very wide openings, the stack becomes noticeable.
Thresholds and level access
Thermal performance and Part L
Modern aluminium doors of either type perform well when you choose good glazing. Double-glazed units typically achieve U-values of 1.2 to 1.6 W/m²K, and triple glazing 0.8 to 1.0. Building regulations (Approved Document L) require replacement doors in England to achieve 1.4 W/m²K or better, and new extensions have their own overall targets, so ask for the certified U-value of the whole door, not just the glass. Thermally broken aluminium frames, warm-edge spacers and argon-filled units are the standard specification now. Neither type is inherently warmer than the other; the quality of the system is what matters.
Security
Both can be highly secure. Look for a system tested to PAS 24, multi-point locking on every panel, anti-lift blocks so panes cannot be levered off the track, and toughened or laminated glass. Bifolds have more locking points because they have more panels; sliders rely on a strong interlock and hook locks. A properly fitted, well-specified door of either style meets modern security standards and mortgage lender expectations.
Weather, maintenance and cleaning
Both types run on a bottom track that collects grit, leaves and the occasional toy, and both need that track sweeping or vacuuming regularly to keep rollers running smoothly. Hinges and locks benefit from a light lubrication once a year. Aluminium frames need nothing more than washing; timber needs repainting or re-oiling every few years. Check the seals and drainage slots each autumn and both will last decades.
Ventilation, privacy and blinds
A sliding door gives you a controllable gap for ventilation without opening the whole wall; a bifold's traffic door does the same job. For privacy and shading, integral blinds sealed between the glass panes are the neatest solution for either type, because a full-width opening is awkward to curtain. Solar-control glass is worth considering on a south-facing extension to keep the room from overheating, which building regulations now consider under Part O for new homes.
Configurations and alternatives
- Open-corner sets: two runs of bifolds or sliders meeting at a corner with no post, so the whole corner disappears. Spectacular, and expensive.
- Pocket sliders: panes slide into a cavity in the wall, giving a completely clear opening. Needs planning at the design stage.
- Bifold with fixed panes: a bifold set beside a fixed glazed panel, combining a full opening with an uninterrupted view.
- French doors: a pair of hinged doors. Cheaper at £1,200 to £3,000 installed and often the right answer for openings under two metres or period homes.
- Crittall-style steel-look doors: slim black frames in an industrial style, available in aluminium at a premium.
Planning, building regulations and certification
Fitting doors as part of an extension is covered by the extension's own planning route and building control application. Replacing an existing door with bifolds or sliders does not normally need planning permission, except on listed buildings, in conservation areas with an Article 4 direction, or on flats. Replacement glazing must be installed by a FENSA or CERTASS registered installer, who certifies the work, or you need a separate building control application. Lead times run four to ten weeks from order, and most quality systems carry a ten-year guarantee on frames and hardware. Our planning permission guide covers the wider rules.
Which should you choose? A decision checklist
- Opening under 4 m: bifolds
- Opening over 5 m: sliding doors
- Between 4 and 5 m: decide on the next two questions
- You want the whole wall open in summer: bifolds
- The view when closed matters most: sliding doors
- Tight kitchen with no spare wall for stacked panels: sliding doors
- Tightest budget on a standard opening: sliding doors or uPVC bifolds
- Level threshold for a wheelchair or pushchair: either, specified flush at the design stage
- Period home or conservation area: timber or steel-look, in either type
There is no universally "best" option, only the right one for your space. On our Locks Heath kitchen extension the client chose bifolds so the kitchen-diner could open straight onto the garden across the full width, exactly the kind of decision we help clients weigh up at the design stage.
What we fit in Southampton
We fit bifold and sliding doors as part of extensions and renovations across Southampton, Fareham, Hedge End, Eastleigh and the surrounding area, handling the structural opening, steel, threshold drainage and building control as one job. Typical installed prices locally sit in the ranges above; the South East premium on labour is modest for glazing because the doors themselves are the main cost.
Bifold, sliding or French doors?
| Feature | French doors | Bifold doors | Sliding doors |
|---|---|---|---|
| Installed cost, aluminium | £1,200 – £3,000 | £3,000 – £7,500 | £1,800 – £4,500 (standard) |
| Ideal opening width | Up to 2 m | 2 – 5 m | 3 m and up |
| Clear opening | Full width | Around 90% | 50 – 66% |
| Look | Traditional, symmetrical | Contemporary, full-wall | Minimal, maximum glass |
| Best for | Period homes, small openings | Garden connection | Views, wide openings |
French doors are often the right answer for a small opening or a period property, and they are the cheapest of the three.
Sizes and configurations
| Opening width | Bifold configuration | Sliding configuration |
|---|---|---|
| 1.8 – 2.4 m | 2 or 3 panels | 2 panes |
| 2.4 – 3.6 m | 3 or 4 panels | 2 or 3 panes |
| 3.6 – 4.8 m | 4 or 5 panels | 3 panes |
| 4.8 – 6 m | 5 or 6 panels | 3 or 4 panes |
| 6 – 8 m | 6 or 7 panels | 4 panes or two sets |
Bifolds can be configured to fold to one side or split, for example three panels left and two right, and to open from the inside or outside. Sliders can be two-pane with one fixed, three-pane with the centre sliding, or four-pane opening from the middle.
Glass options
Toughened glass is the minimum for safety in a door; laminated glass adds security and sound reduction. Solar-control coatings cut heat gain on a south or west-facing extension, low-emissivity coatings cut heat loss, and self-cleaning glass uses a coating that breaks down dirt for the rain to wash off, useful on a roof lantern above the doors. Triple glazing improves the U-value to 0.8 to 1.0 W/m²K and reduces noise, at 15 to 25 per cent more than double. Integral blinds sit between the panes and never need cleaning.
Colours and finishes
Aluminium doors come powder-coated in any RAL colour, with anthracite grey, black and white the most popular, and dual colour lets you match a dark exterior with a white interior. Woodgrain-effect finishes give the look of timber with none of the maintenance. Matt finishes hide fingerprints better than gloss on a door that gets handled every day.
What installation day looks like
Once the structural opening and steel are in place, a standard set takes one to two days. The frame is levelled and fixed first, because a frame out of square is the root of every sticking bifold; the threshold is bedded and sealed, or a flush channel is installed; the panels are hung and adjusted so they meet evenly; the locks are aligned; and the perimeter is sealed inside and out. The installer then tests every panel through its full travel. On a good install, the doors glide with one finger; on a poor one they never will.
Common mistakes to avoid
- Fitting doors before the structural opening is right. An opening a few millimetres out of square causes years of sticking.
- Choosing the biggest opening the wall allows without thinking about where bifold panels will stack.
- Ignoring orientation. A south-facing wall of glass without solar control or shading overheats in summer.
- A flush threshold with no drainage channel, which lets rain track inside.
- Buying on price alone. The frame system, the glass specification and the installer matter more than the brand name.
Resale and kerb appeal
Large glazed doors are one of the features estate agents photograph first, and an extension with bifolds or sliders opening onto a garden consistently shows better than the same room with a window and a single door. They do not add value on their own, but they make the extension that contains them worth more, and they are part of why a well-designed kitchen extension adds more than it costs on the right street.
Planning an extension with bifolds or sliders?
We help you choose the right glazing for your space and fit it properly as part of the build, with the structural opening and threshold done right. Book a free site visit.
The doors are one of the most visible parts of an extension, so it is worth getting the choice and the installation right first time. Prices in this guide are based on our own quotes and published UK trade guides and are correct as of August 2026.
Frequently asked questions
Are bifold or sliding doors more expensive?
On a standard three to four metre opening, sliding doors are the cheaper option: around £1,800 to £4,500 supplied and fitted for a two or three-pane aluminium slider against £3,000 to £7,500 for an aluminium bifold set. Go slimline or very wide and it reverses, with premium sliding systems at £5,000 to £12,000 or more. The steel, knock-through and building control cost the same whichever you choose.
Which lets in more light, bifolds or sliding doors?
Closed, a sliding door: two panes with a 20 to 35 mm interlock is almost all glass, where a five-panel bifold puts four 100 to 130 mm frames across the view. Open, a bifold: folded back it clears around 90 per cent of the span against 50 to 66 per cent for a slider. Since the doors are shut for most of the year, that closed view is the number to weigh most heavily.
Do bifold doors have a big threshold to step over?
Only if you let them. The standard weathered threshold stands 15 to 20 mm proud, fine for most homes, and a flush threshold with a drainage channel outside gives a completely level run from kitchen floor to patio, which matters for wheelchairs, pushchairs and toddlers. Specify it at the design stage, because the channel and the falls outside are far easier to build into an extension than to add later.
Are sliding doors more secure than bifolds?
Both can be very secure when you choose a system tested to PAS 24 with multi-point locking, anti-lift blocks and toughened or laminated glass. Security depends on the quality of the door and the installation far more than on whether it folds or slides.
Which is better for a small extension?
For openings under about four metres, bifolds usually make more sense: a three-panel set opens the whole span and suits a narrow run well. For a wide opening of five metres or more, sliding doors tend to look better because the panes can be enormous and the view when closed is almost uninterrupted.
Do I need planning permission for bifold or sliding doors?
Not usually. Replacing an existing door or window, or fitting doors as part of a permitted development extension, does not normally need planning permission. The exceptions are listed buildings, homes in conservation areas with an Article 4 direction, and flats. Building regulations still apply, and the doors must meet the thermal and safety-glazing requirements.
Aluminium or uPVC: which should I choose?
Aluminium for almost every extension. It is stronger, so the frames are slimmer and the panels can be larger, it does not warp or discolour, and it comes in any colour. uPVC is cheaper, at roughly £2,000 to £4,200 for a bifold set, but the chunkier frames and limited spans show. Timber suits period homes and conservation areas but needs maintenance.
What is the maximum width for bifold and sliding doors?
Bifold panels are generally limited to around 1.2 metres wide each, so a seven-panel set spans about eight metres. Individual sliding panes can be 2.5 to 3 metres wide, and some slimline systems go larger, which is why sliders suit very wide openings. Height is typically up to 2.4 to 3 metres for both.
Are bifold doors high maintenance?
No, but the bottom track collects grit and leaves and needs sweeping or vacuuming regularly to keep the rollers running smoothly. Sliding doors have the same issue with their track. Hinges and locks on both types benefit from a light lubrication once a year. Aluminium frames just need washing.
How long do bifold and sliding doors take to arrive and fit?
Lead times are typically four to ten weeks from order, longer for bespoke colours or very large sliding panes, so order early in an extension build. Fitting takes one to two days for a standard set once the structural opening is ready. If the doors are replacing an existing door, the installer must be FENSA or CERTASS registered or the work needs a building control application.