Most sliding patio door problems are caused by worn, broken or seized rollers, a damaged or dirty track, or a door that has dropped so the lock no longer meets its keep. These can usually be repaired by replacing the rollers, adjusting the door height and resetting the keeps. We also replace misted or broken glass units in existing patio door frames and renew tired seals.
How does a sliding patio door work?
An in-line sliding patio door has at least one moving sash that runs on rollers along a track in the bottom of the frame, guided at the top by a channel. Most uPVC and aluminium patio doors use adjustable rollers, so the height of the sash can be set to run level and line up with the lock. The lock itself is usually a hook-type multipoint lock operated by a handle on the inside and a euro cylinder from the outside.
Because each sliding sash carries a large sealed glass unit, it is heavy. Everything that goes wrong tends to follow from that weight: rollers flatten and wear, the sash drops, the lock stops engaging, and the seals are dragged out of position. This is one of the more mechanical parts of our double glazing repair service, and catching it early usually makes the repair simpler.
Signs your patio door needs repair
- It takes two hands or a shove to open or close.
- It grinds, judders or makes a scraping noise as it slides.
- The sash jumps off the track or tilts as it moves.
- The handle will not lift or the lock will not engage unless you push the door hard against the frame.
- You can see daylight or feel a draught along the meeting stiles or the top.
- Water collects in the track and does not drain away.
- Condensation or a haze has appeared between the panes of glass.
What we repair on patio doors
| Problem | Usual cause | Typical repair |
|---|---|---|
| Heavy or grinding slide | Worn or broken rollers, debris in the track | New rollers, track cleaned and checked |
| Door jumping the track | Collapsed roller or damaged track | Rollers replaced, track repaired or capped where possible |
| Will not lock | Sash dropped, keep out of line, worn lock | Height adjusted, keeps reset, lock or gearbox replaced |
| Draughts and rattles | Brush seals and gaskets worn or displaced | Seals renewed, sash realigned |
| Misted or cracked glass | Failed or damaged sealed unit | Made-to-measure safety glass unit fitted in the existing frame |
Patio door rollers: why they fail
Rollers are the part that does most of the work. Grit in the track, a sash set too low so it drags, or simply years of use wear the wheels down until they flatten, crack or seize. Once one roller fails, the sash tilts and the others take extra load, so wear speeds up. Replacing rollers means lifting the sash out of the frame, which is a job for two people because of the weight of the glass, and it is not something we suggest trying yourself. Rollers vary between makers, so a photo of the bottom of the sash or any name on the frame helps us find the right ones.
What you can safely do is keep the track clean. Vacuum or brush out grit and leaves, and wipe the track down. Do not oil a track unless the door maker recommends it, as oil holds on to dirt.
Glass in patio doors
Patio doors are a critical location under Approved Document K, so any glass in them must be safety glass, either toughened or laminated. If a unit has misted or cracked, we measure it and order a replacement sealed unit made to suit the existing frame, then fit it at a second visit. This is a glazing-only repair, so the frame stays where it is. For more about failed units in general, see our misted double glazing repair page.
Patio doors across Merseyside
Sliding patio doors and bi-folds are common on larger homes and extensions, and in coastal areas such as Formby and Crosby wind-driven rain and sand in the track add to the wear on rollers and seals. We also see plenty of older sliding doors on inter-war and post-war semis in suburbs like Allerton. If you have folding doors rather than sliders, our bi-fold door repair page covers the different runners and hinges they use.
What affects the price of a patio door repair?
Cost depends on what needs doing: rollers, a lock or gearbox, seals, glass, or a combination. The make of door affects how easy parts are to source, and glass units vary with size, type and whether they are toughened or laminated. We quote in writing after looking at the door.
If the door is still covered by an installer's guarantee, check the terms before arranging a repair elsewhere.
Patio door sticking or not locking?
Describe the problem and send a photo if you can. Call 07777 659786 or use the form, and we will call you back to talk through your window and door repairs on Merseyside.
Frequently asked questions
Can patio door rollers be replaced?
Yes, on most uPVC and aluminium sliding doors the rollers can be replaced. The sash has to be lifted out of the frame, so it is a two-person job because of the weight of the glass. Rollers vary between door makers, so we identify the type before ordering, and a photo of the bottom of the sash helps.
Why does my patio door keep coming off the track?
A sash usually jumps the track because a roller has collapsed or worn unevenly, the track is damaged or bent, or the door has been set too high or low. Debris in the track can also lift a roller out. Replacing worn rollers and checking the track normally stops it happening again.
My patio door will not lock. What is wrong?
Often the sash has dropped slightly, so the hooks on the lock no longer line up with the keep. Adjusting the roller height and resetting the keep usually fixes it. If the handle feels loose or will not move at all, the lock or gearbox may need replacing instead.
Should I oil my sliding door track?
Usually not. Oil and grease on a track tend to collect grit, which speeds up roller wear. Keeping the track clean with a brush and vacuum is generally better. The locking points are different: a light lubricant as the door maker recommends helps those work smoothly.
Can you replace just the glass in a sliding patio door?
Yes. If a sealed unit has misted or cracked, we can fit a new made-to-measure unit in the existing frame. Glass in a patio door must be toughened or laminated safety glass. The new unit is ordered after measuring and fitted at a second visit.
Is it worth repairing an old patio door or should I replace it?
If the frame is sound and square, repair is often the sensible choice: new rollers, an adjusted sash, fresh seals and a new lock or cylinder can make an older door work well again. If the frame is badly damaged or distorted, we will say so honestly. Full door replacement is not something we offer, so our advice is about what a repair can realistically achieve.