The short answer
Bifold doors are adjusted using the built-in roller and hinge adjusters. When panels start to drag, catch, drop at a corner, or fail to meet cleanly, it usually means the alignment has drifted and a small adjustment is needed. Most systems have adjustable rollers at the bottom that raise or lower the panel height, and adjustable hinges that fine-tune how the panels sit relative to each other, reached with an Allen key or screwdriver. The first step is always to clean the track, since debris is the most common cause of dragging. If the doors are still misaligned after cleaning, small turns of the adjusters bring them back into line. Because over-adjustment can cause new problems, and the right adjuster varies by system, many homeowners have a professional realign them — especially under warranty.
Bifold doors drift out of alignment over time, but the fix is usually a small adjustment rather than a repair. Here is how to diagnose the problem and what the adjusters do.
Realignment basics
- First checkClean the track of debris
- Height / dropRoller adjusters at the base
- Panel-to-panel fitHinge adjusters
- ToolsUsually an Allen key
- When unsureUse a professional / warranty
Diagnosing the problem first
Before adjusting anything, work out what the doors are actually doing, because the symptom points to the cause. Common signs that bifolds need attention include panels that drag along the track, a panel that has dropped at one corner so it no longer sits square, doors that catch or rub against each other or the frame, gaps where the panels should meet cleanly, or a lock that no longer engages smoothly. Each of these usually indicates the alignment has drifted slightly from where it was set at installation.
The essential first step — before touching any adjuster — is to clean the bottom track thoroughly. A surprising number of "misalignment" problems are simply grit and debris in the channel stopping the rollers running freely, which mimics or causes dragging. Vacuum and wipe the track, check the rollers are clear, and operate the doors again. If the problem disappears, no adjustment is needed. Only if the doors remain stiff, dropped or misaligned after a clean track has been confirmed should you move on to the adjusters. Diagnosing properly this way avoids unnecessary fiddling with settings that were correct to begin with, and it is the step professionals always do first.
What the adjusters do
Bifold systems are designed to be fine-tuned, with adjusters built into the hardware. The two main types are:
- Roller (height) adjusters: located at the bottom of the panels where they sit in or on the track. Turning these raises or lowers the panel, correcting a dropped corner or a panel that is dragging because it sits too low. Small, equal adjustments keep the panel level.
- Hinge adjusters: the hinges connecting the panels, and connecting the lead panel to the frame, often allow fine adjustment of how the panels sit side to side and in or out. This corrects panels that catch each other or do not meet flush.
The adjusters are typically turned with an Allen (hex) key or screwdriver. The golden rule is to make small adjustments — a fraction of a turn at a time — then test the doors before adjusting further, because the panels in a bifold are interdependent and a large change in one place can throw out the whole run. It also helps to know your specific system: manufacturers position and label adjusters differently, and consulting the installation or maintenance guide for your doors avoids turning the wrong screw.
When to adjust yourself and when to call a pro
A confident, careful homeowner can often handle minor realignment — cleaning the track and making small roller or hinge tweaks to correct a slightly dragging or dropped panel — provided they have the right tool, work patiently, and follow the manufacturer's guidance for their system. Done methodically, it is a reasonable DIY task and restores smooth operation.
There are good reasons to call a professional, though. If the doors are still under warranty, a professional adjustment keeps cover intact and the supplier may carry it out as part of the warranty service. If the misalignment is significant — large gaps, panels badly out of square, hardware that seems worn or damaged, or a frame that may itself have moved — that points to something beyond a simple tweak, and a specialist should assess it. The same applies if repeated small adjustments do not hold, which can indicate a deeper issue such as a settling frame or a structural problem above the opening. As a rule of thumb: clean the track and try gentle adjustment for minor drift, but bring in an expert for anything substantial, anything under warranty, or anything that does not respond to careful tuning. Catching alignment problems early — before a dragging panel wears the rollers or track — keeps the repair small either way.
Preventing misalignment in the first place
The best realignment is the one you never need, and most alignment problems are preventable with the same light maintenance that keeps bifolds running smoothly. The dominant cause of drift is a dirty track: grit and debris force the rollers to work harder, wearing them and gradually pulling the panels out of true. Keeping the bottom track clean and clear — vacuumed and wiped regularly, especially where the doors open onto a garden — removes the single biggest source of misalignment before it starts.
A few other habits help too. Operate the doors gently, letting the mechanism do the work rather than shoving or slamming the panels, since rough use stresses the hinges and rollers and accelerates drift. Lubricate the moving parts a couple of times a year with a suitable light product so the hardware runs freely rather than binding. And address small issues early: a panel that has just started to catch or drag is a quick clean or a fractional adjuster turn away from being fixed, whereas a problem left for months can wear the rollers, damage the track, and turn a minor tweak into a repair. Watching the seals and the threshold drainage also matters, because water sitting at the base or a sagging frame can both contribute to alignment trouble. In short, the routine that keeps bifolds smooth is also the routine that keeps them aligned — a clean track, gentle use, occasional lubrication and prompt attention to small symptoms together prevent most of the realignment work owners would otherwise face.
Frequently asked questions
Why do bifold doors drop or sag over time?
The most common causes are a dirty track stopping the rollers running freely, the rollers needing a height adjustment, or normal settling that has shifted the alignment. Clean the track first; if a panel still sits low or drags, the roller height adjusters usually correct it. Significant or persistent sagging warrants a professional check.
Can I adjust bifold doors myself?
Often yes, for minor drift. After confirming the track is clean, small turns of the roller (height) and hinge adjusters with an Allen key can realign panels that drag or do not meet cleanly. Make small adjustments and test as you go. For significant misalignment, or while under warranty, use a professional.
What tools do I need to realign bifold doors?
Usually an Allen (hex) key or screwdriver to turn the roller and hinge adjusters, plus a vacuum and cloth to clean the track first. Check your manufacturer's maintenance guide, as the size of key and the location of adjusters vary between systems. Work patiently with small adjustments.
Sources & further reading
Figures on this page are typical UK ranges drawn from published sources and depend on your specific opening and material. They are guidance, not a quotation.