A bifold door is one of the most misunderstood products in the internal door market. People assume it is a complicated piece of engineering. In reality it is a pair of door panels, joined by hinges, that hang from a track at the top and pivot on a single fixed point at the top and bottom of the opening. Understand those three components and the whole system makes sense.
This guide explains exactly how an internal bifold door works, what parts you get in a kit, what sizes are sold in the UK, what they actually cost, how to fit one, and where a bifold is the wrong choice. Every price and product count in this guide comes from our own live stock at Doors2Floors bi-fold doors, where we currently list 15 bifold products alongside a wider range of over 710 internal doors.
How a Bifold Door Actually Works
A bifold door does not slide, and it does not swing on butt hinges like a standard door. It does both, in a small way, at the same time.
The Track and Roller System
A track is screwed into the underside of the door head. A guide roller sits inside that track and is fitted into the top edge of the leading panel. As the door opens, the roller travels along the track and pulls the leading edge of the door sideways.
The Pivot Points at Top and Bottom
The panel nearest the hinge side does not travel. It is held by a top pivot that locates in a bracket at one end of the track, and a bottom pivot that sits in a floor bracket screwed to the floor or the frame leg. That panel only rotates. It stays in the same place in the opening.
The Folding Hinges Between Panels
Between the two panels sit a set of butt hinges, usually three per pair on a standard height door. These allow the two panels to close against each other like a book. The hinges are what turn two separate leaves into a folding unit.
What Bifold Actually Means
Bi means two and fold means fold, so a bifold is a door that folds in two. A four panel set is really two bifold pairs meeting in the middle, which is why suppliers sell them as pairs rather than as single sets.
Why the Opening Is Never the Full Door Width
This is the single most common misunderstanding. When a bifold folds back, the two panels stack against the pivot side. That stack is roughly the thickness of two doors plus the hinge knuckles, typically 80mm to 90mm on a 35mm door. So a 762mm bifold gives you an actual clear opening of about 660mm to 680mm, not 762mm, and certainly not double the width. Any claim that a bifold creates an opening twice as wide as its closed width is simply wrong.
Why Bifolds Feel Effortless
Most of the door weight is carried by the fixed pivot, and the moving edge is supported by a roller running on nylon or steel bearings. Once the track is level and the pivots are plumb, the door moves with very little force. When a bifold is stiff, the cause is almost always an out of plumb opening or a track that is not level, not a fault in the door.
Internal Bifold Doors and External Bifold Doors Are Not the Same Product
Search results mix these two together constantly, and it causes real buying mistakes.
What an Internal Bifold Is Designed For
An internal bifold is a timber, laminate or primed door panel, usually 35mm thick, hung on a lightweight top track. It is designed for cupboards, wardrobes, utility spaces and narrow openings inside a heated, dry building. It has no weather seal, no thermal rating and no security rating.
What an External Bifold Is Designed For
An external bifold is an aluminium or timber framed glazed system with a structural bottom track, multi point locking, weather gaskets and double or triple glazed units. It is a glazing product, not a joinery product, and it is quoted, surveyed and installed as a system.
Why the Two Are Never Interchangeable
An internal bifold panel has no weather protection and no load bearing bottom track. Fitting one in an external opening will lead to swelling, delamination and failure within a season. The reverse also fails: an external system is far too heavy and deep for an internal stud opening.
What Doors2Floors Supplies
We supply internal bifold doors and internal bifold frame kits. If you need an external opening covered, look at our over 90 external doors or our over 30 glazed external doors instead, and speak to a glazing specialist about a folding sliding system.
The Parts of an Internal Bifold Door System
When people say a bifold is complicated, what they usually mean is that a kit contains more parts than a standard door. Here is what each one does.
The Door Panels
Two matched leaves, typically 35mm thick, supplied as a pair. Bifold panels are narrower than standard doors because two of them together have to fit the opening.
The Top Track
An aluminium or steel channel screwed to the underside of the head. It must be dead level. A track that drops even 3mm across its length will make the door swing open or closed on its own.
The Top Pivot and the Guide Roller
The top pivot is a threaded pin in the hanging panel that drops into an adjustable bracket at the end of the track. The guide roller is a wheel in the top of the leading panel that runs in the track. Adjusting the pivot height is how you set the gap at the head.
The Bottom Pivot and Floor Bracket
A pin in the bottom of the hanging panel drops into a bracket fixed to the floor or the frame leg. It carries most of the door weight, so it needs a solid fixing, not a plug in soft plaster.
Aligners and Snugger Springs
An aligner is a small nylon guide fitted to the back of the leading panel that keeps the folded pair sitting flush when closed. A snugger spring holds the door lightly against the jamb so it does not drift. Most kits include one or both.
The Bifold Frame Kit
A bifold frame kit gives you the lining, the track, the pivots and the stops as a matched set, cut for a specific opening size. It removes most of the guesswork. Our kits include the Deanta White Primed Bifold Frame Kit at £345.50, the Deanta Oak Bifold Frame Kit Fully Finished at £391.50, the Deanta Oak Bifold Frame Kit Unfinished at £375.75, and the Deanta Walnut Bifold Frame Kit at £406.25. Each is available in six size options.
Door Knobs Rather Than Lever Handles
Bifolds take a knob, not a lever, because a lever would foul the adjacent panel as the door folds. We list over 40 door knobs suitable for this.
Bifold Door Configurations Explained
Two Panel Bifold
The standard arrangement. Two panels folding to one side, used for cupboards, wardrobes and single door openings. This is what most of our 15 bifold products are.
Four Panel Bifold
Two bifold pairs, one hung on each side of a wider opening, meeting in the centre. Used for double wardrobes and wide storage runs. You buy two pairs and two tracks, or one long track cut appropriately.
Left Hand and Right Hand Hanging
A bifold pair is symmetrical, so the same set can be hung to fold left or fold right. You decide the hand on site by choosing which end of the track takes the pivot bracket. This is a real advantage over a hinged door, which is handed at the point of fitting the hinges.
Bifold as a Room Divider
A bifold can be used to split a through lounge or separate a dining area, but a purpose built system is usually better for that job. We list 17 room divider products designed for exactly that purpose.
Bifold Wardrobe Doors
The most common domestic use. Bifolds let you see the whole wardrobe interior without needing swing clearance in front of the unit, which matters in a small bedroom where the bed is close to the wardrobe.
Bifold Door Sizes in the UK
Standard UK Bifold Widths
UK internal bifolds are sold by the overall pair width, matched to standard door opening sizes. The common sizes are 610mm, 686mm, 762mm and 838mm overall, with 1981mm the standard height. Some ranges also offer 914mm. Each panel in the pair is therefore roughly half the overall width, less an allowance for the hinge gap.
Reading the Size Label Correctly
A 762mm bifold means the pair measures 762mm across when closed. It does not mean each panel is 762mm. If you order two 762mm pairs expecting to fill a 762mm opening you will have bought twice what you need.
Measuring the Opening
Measure the width in three places, at the head, the middle and the floor, and use the smallest figure. Do the same for the height on both sides and in the centre. Openings in older properties are rarely square, and the smallest measurement is the one that governs.
How Much You Can Trim
Most engineered core bifold panels carry a trimming allowance of around 6mm to 10mm per edge, but you must check the individual product specification because it varies by manufacturer and by panel thickness. Trim equally from both stiles so the panel stays visually balanced. Our guide on how to plane a door covers the technique in detail.
Head and Floor Clearance
Allow roughly 3mm at the head above the track and 6mm to 10mm at the floor, more if a thick carpet is going down later. The bottom pivot bracket takes up floor height, so measure from the finished floor level, not the bare subfloor.
Ceiling Height and Track Depth
The track itself takes 25mm to 35mm of head height. If your opening is already at the minimum, that lost height matters, and a 1981mm bifold may not fit an opening that took a 1981mm hinged door.
Bifold Door Materials and Finishes
White Primed Bifold Doors
Primed panels arrive with a factory base coat and are finished on site in your chosen paint. They are the most economical route and the easiest to match to existing joinery. The LPD Textured 4 Panel Bi-Fold White Internal Door is our entry point at £131.35, with the LPD Textured 6 Panel version at £136.60.
Fully Finished Bifold Doors
Fully finished panels come lacquered or painted from the factory and hang straight out of the box. The LPD Mexicano Fully Finished Oak Bi Fold Door at £273.68 is a good example. We stock over 350 fully finished internal doors across the wider range.
Unfinished Oak Bifold Doors
Unfinished oak lets you control the final colour and sheen. The LPD Mexicano Unfinished Oak Bi Fold Door is £242.93. There are over 80 unfinished internal doors in the range if you want the same approach elsewhere in the house.
Laminated Bifold Doors
Laminate gives a hard wearing surface that resists knocks better than paint, which suits cupboards that get daily use. We list over 20 internal laminated doors.
Smooth and Moulded Panels
A moulded panel gives you the look of a traditional panelled door at a lower price. The Doors2Floors Ashford White Smooth Internal Bi Fold Door at £92.00 is the most affordable bifold pair we carry.
Metal and Composite Bifolds
You will read that metal and composite are internal bifold options. In UK domestic joinery they are not. Metal folding partitions belong in commercial and industrial settings, and composite is an external door material. For an internal opening, timber based panels are what the market actually supplies.
Glazed and Solid Bifold Doors
What Glazing Changes
A glazed bifold borrows light from the brighter room into the darker one. In a hallway or a narrow landing that can make a real difference. We list over 280 glazed doors and over 420 unglazed doors across the full range.
Safety Glass Is Not Optional
Glazing in a door, and in the side panels next to a door, falls into a critical location under UK building regulations. The glass must be toughened or laminated safety glass and it should carry a permanent mark. Internal glazed doors sold in the UK are supplied with safety glass as standard. Never fit a single sheet of ordinary annealed glass into a door.
Clear Glazing
Clear glass maximises light transfer and visual connection. Our LPD Pattern 10 Bi-Fold Glazed Primed White Internal Door at £226.98 and the LPD Shaker 4 Light Bi-Fold Glazed Primed White Internal Door at £264.97 both use clear glass. There are over 110 clear glazed doors in the range.
Frosted and Obscure Glazing
Frosted glass passes light while blocking the view, which is the right answer for anything opening onto a bathroom or a utility. We list over 20 frosted glazed doors.
Unfinished Glazed Options
The LPD Pattern 10 Glazed Bi-Fold Unfinished Internal Door at £272.91 lets you glaze and finish to your own scheme.
Weight Matters More on a Bifold
Glass adds weight to the leading panel, which is the panel hanging from the roller. Check the track load rating before choosing a heavy glazed pair, and make sure the floor bracket is fixed into something solid.
How Much Do Bifold Doors Cost in the UK?
The figure of around £300 that circulates online is a guess. Here is what our own live pricing looks like.
Entry Level Bifold Doors
From £92.00 for the Doors2Floors Ashford White Smooth pair, rising to about £137 for the LPD Textured panels. These are primed or smooth faced pairs for cupboards and wardrobes.
Mid Range Bifold Doors
Between roughly £180 and £240. The LPD Pattern 10 Bi-Fold Primed White Internal Door sits at £182.52 and the LPD Vancouver Bi-Fold Primed White Internal Door at £232.44.
Premium Bifold Doors
From roughly £260 to £320. The LPD Mexicano Bi-Fold Primed White Internal Door is £319.36, and the fully finished oak Mexicano is £273.68.
Frame Kit Costs
Bifold frame kits run from £345.50 for white primed up to £406.25 for walnut. A frame kit is a significant part of the budget and is easy to forget when comparing door prices.
Hardware and Extras
Add a knob, a magnetic catch and a door stop. We carry over 2,900 door hardware lines and over 30 door stops, so most budgets are covered.
Fitting Costs
A joiner will typically charge for half a day to fit a bifold pair into a prepared opening, and a full day if the lining needs replacing. Prices vary widely by region, so get a local quote rather than relying on a national average.
Where to Save Money
Our over 20 clearance doors often include discontinued lines at a substantial reduction, which suits a cupboard where the door will not be on show.
Where Bifold Doors Work Best
Wardrobes and Fitted Storage
The classic application. A bifold needs almost no clearance in front of it, so you can place a bed or a chest of drawers close to the wardrobe without blocking access.
Airing Cupboards and Utility Spaces
Narrow openings where a hinged door would swing into a corridor. A bifold folds flat against the reveal and keeps the walkway clear.
Small Bedrooms and Box Rooms
Where the swing arc of a standard door would eat a metre of usable floor. A bifold reclaims most of that.
En Suites and Cloakrooms
Possible, but think carefully. Bifolds do not seal well and do not take a mortice lock easily, so privacy and moisture are both compromises.
Where a Bifold Is the Wrong Choice
Avoid a bifold anywhere you need acoustic separation, a fire rating, a proper lock, or a door that will be opened and closed dozens of times a day. In those situations a standard hinged door from our over 710 internal doors is the better product.
Bifold Doors Compared With Other Space Saving Options
Bifold Compared With Sliding
A sliding door needs a clear run of wall beside the opening. A bifold does not, because it folds into the opening itself. But a sliding door gives a wider clear opening for the same nominal size. We list 16 sliding door kit systems.
Bifold Compared With a Pocket Door
A pocket door disappears completely and gives the cleanest result, but it needs a cavity built into the wall, which means structural work. We carry 4 pocket doors. A bifold is retrofittable in an afternoon.
Bifold Compared With a Standard Hinged Door
A hinged door seals better, locks properly, blocks more sound and can be fire rated. A bifold wins only on floor space. Choose on the basis of what the opening actually needs.
Bifold Compared With a Room Divider Set
Room divider sets are engineered for large openings with matched frames and multiple leaves. For anything above about a metre wide, a divider set will look and perform better than a chain of bifolds.
How to Fit an Internal Bifold Door
This is a realistic sequence for a competent DIYer. If the opening needs structural alteration, or if you are unsure, use a qualified joiner.
Tools You Will Need
A spirit level of at least 900mm, a tape, a pencil, a cordless drill and driver, a hand plane or electric planer, a sharp chisel, a bradawl, and a set of packers or shims. A mitre saw is useful if you are also fitting architrave.
Step One: Check the Opening
Level the head, plumb both jambs, and check the floor. Correct the opening before you touch the door. Almost every bifold that will not run properly has an opening problem behind it.
Step Two: Fit the Track
Mark a level line on the underside of the head and fix the track to it. Screw into solid timber, not plasterboard. Check the level again after fixing, because tightening screws can pull the track out of true.
Step Three: Fit the Bottom Bracket
Drop a plumb line from the top pivot bracket to the floor and mark the position. The two pivots must sit on the same vertical axis. If they do not, the door will bind.
Step Four: Prepare the Panels
Trim the panels to size if required, keeping within the manufacturer allowance. Drill the pilot holes for the pivots and the roller, and fit the hinges between the two leaves. Our guide on where to fit door hinges covers hinge positioning.
Step Five: Hang the Door
Insert the top pivot into its bracket first, then locate the roller in the track, then drop the bottom pivot into the floor bracket. Two people make this much easier on a glazed pair.
Step Six: Adjust
Wind the top pivot up or down to set the head gap, then adjust the pivot laterally to close the gap at the jamb. Work in small increments and test the fold after each change.
Step Seven: Fit the Aligner and the Hardware
Fit the aligner so the panels sit flush, then add the knob, the magnetic catch and the door stop.
Step Eight: Finish the Trim
Fit the architrave last, once the door is running properly. We list 16 door architrave products, and our guide to door architraves explains the mitre work.
Technical Points People Get Wrong
Assuming the Opening Is Square
It rarely is. Measure, do not assume, and shim the lining before the door goes anywhere near it.
Trimming Too Much Off One Edge
Taking all the reduction from one stile puts the hinge screws into the softer core and unbalances the look. Split the reduction between both edges.
Skipping the Aligner
Without the aligner the two panels will not sit flush and the door looks permanently half open. It takes five minutes to fit.
Forgetting the Finished Floor Level
Fitting to bare boards and then laying a 15mm floor and underlay will jam the door. Work from the finished level. If you are laying new flooring, our 12 flooring products all state their finished thickness.
Overloading the Track
Every track has a weight limit. A heavy glazed oak pair on a light duty track will sag and eventually jump out.
Fixing the Floor Bracket Into Nothing
The bottom pivot carries the load. A wall plug in soft plaster will pull out. Fix into the frame leg or into solid substrate.
Bifold Door Hardware
Knobs Rather Than Levers
A lever handle projects far enough to catch the adjacent panel as the door folds. Use a knob. Browse over 40 door knobs or the full over 2,500 door handles range.
Magnetic Catches
A small magnetic catch at the leading edge keeps the pair closed without a latch. It also stops the door drifting on a slightly out of level track, though it is not a substitute for levelling the track properly.
Hinges Between the Panels
Standard butt hinges, three per pair on a 1981mm door. We list over 350 door hinges.
Door Stops
A stop prevents the folded panels being pushed back into the reveal and damaging the plaster. We list over 30 door stops.
Finishing an Unfinished or Primed Bifold Door
Finish Before You Hang
Finish the panels flat, on trestles, before hanging. It gives a better result and lets you reach the edges properly.
Seal All Six Faces
Most manufacturers require every face and every edge, including the top and bottom, to be sealed. Skipping the top edge is the classic mistake and it lets moisture into the core.
Priming and Painting
A primed door still needs at least two topcoats. Our guide on painting and maintaining a door covers the process, and the pre-finished, unfinished and primed doors guide explains which route suits which project.
Guarantee Conditions
Manufacturer guarantees are usually conditional on the door being properly acclimatised and sealed within a stated period of delivery. Read the paperwork that comes with the door.
Choosing a Finish
Our guide to door finishes and the complete guide to internal door finishes compare lacquer, paint, oil and wax.
Maintaining a Bifold Door
Keep the Track Clean
Dust and carpet fibre build up in the channel and are the usual cause of a stiff or noisy bifold. Vacuum the track and wipe it out twice a year.
Check the Pivots
Pivot pins work loose over time. A quarter turn on the adjuster restores the gap. Do not force a door that has dropped.
Re-adjust After Building Settlement
New build properties move in the first two years. A bifold that ran perfectly at handover may need resetting once, and that is normal.
Cleaning the Panels
A damp cloth and a mild detergent. Avoid solvent cleaners and abrasive pads on laminate and lacquered surfaces.
Avoid Lubricating Sprays on the Track
Oil attracts dust and turns into a paste. If the roller squeaks, clean it. Use a dry film lubricant only if the manufacturer recommends one.
Can a Bifold Door Be a Fire Door?
Why Standard Bifolds Are Not Fire Rated
A fire door has to close fully into a rebated frame against intumescent seals, held by a self closing device. A bifold folds rather than closes into a rebate, and the folding joint cannot be sealed to the same standard. For that reason internal bifolds are not normally supplied with a fire rating.
Where a Fire Door Is Required Instead
If the opening is one that needs a rated door, fit a rated door. We list over 240 fire doors, including over 150 FD30 fire doors and 11 intumescent strips and pads. Our article on fire door materials explains what these doors are made of.
Get Advice Before You Decide
Fire door requirements depend on the building, the layout and the use. Confirm what is needed with your local building control body or a competent fire safety professional before ordering.
Buying Bifold Doors from Doors2Floors
The Range
We currently list 15 bi-fold doors, including primed, laminated, oak and glazed options, drawn from our over 250 Deanta, over 500 LPD and over 90 Doors2Floors own brand product lines.
Frame Kits and Linings
Four matched bifold frame kits, plus over 30 internal frames if you are working to a non standard opening.
Delivery
Delivery options and lead times are set out on our delivery page.
Bespoke Sizes
If nothing standard fits, our bespoke service can help.
Talk to Us First
Doors2Floors has supplied doors and flooring to homes and businesses across the UK. If you are unsure whether a bifold is right for your opening, contact our team before you order. You can also read more about us and the brands we carry.
Frequently Asked Questions About Bifold Doors
Do bifold doors need a bottom track?
Internal bifolds do not run on a bottom track. They use a single bottom pivot bracket at the hanging side. Only external folding sliding systems use a full bottom track.
How wide an opening can a bifold cover?
A single pair comfortably covers up to around 838mm. Beyond that you use two pairs, or a room divider set.
Can I fit a bifold door myself?
Yes, if the opening is square and you are comfortable with a level and a drill. The difficulty is always in the opening, not the door.
Are bifold doors noisy?
A correctly fitted bifold on a clean track is quiet. Noise means dirt in the track, a loose roller or an out of level head.
Can bifold doors be trimmed?
Usually yes, within the manufacturer allowance, which is commonly 6mm to 10mm per edge. Always check the specific product specification.
Do bifold doors come as a pair?
Yes. Internal bifolds are sold as a matched pair of panels, priced per pair.
What thickness are internal bifold doors?
Most UK internal bifolds are 35mm thick.
Can I put a lock on a bifold door?
Not a conventional mortice lock. Bifolds take a knob and a magnetic catch. If you need a lock, choose a hinged door and browse our over 720 locks and latches.
Do bifold doors reduce sound between rooms?
Very little. The folding joint and the gaps around the panel let sound through. For acoustic separation choose a solid core hinged door.
Are grey bifold doors available?
Our current bifold range is primed white, oak and textured. For grey we list over 60 internal grey doors in hinged formats, and our guide to the best grey internal doors covers the options.
Can a bifold door be used externally?
No. Internal bifold panels have no weather protection. Use a purpose made external folding sliding system.
How long do bifold doors last?
A well fitted, well maintained internal bifold in a domestic setting should last the life of the joinery. Tracks and rollers are the wear items and are usually replaceable.
This article is general guidance for UK homeowners. Building regulations, fire safety requirements and manufacturer specifications vary. Always check the specification supplied with your door and consult a qualified professional or your local building control body where compliance is involved.