The gear in a folding door is precision hardware carrying a lot of weight through a lot of cycles. It does not need much, but the little it needs is not optional. Most of the "the doors have gone stiff" calls we hear about would have been prevented by a brush and ten minutes.
Twice a year is the right rhythm: once in spring before the doors get heavy use, once in autumn before the weather arrives. Put it in the calendar next to the boiler service.
The tracks, which is most of it
The bottom track collects grit, and grit is what wears rollers and guides. Vacuum it out first, then run a stiff brush along the channel, then wipe with a damp cloth. Pay attention to the ends of the run, where debris accumulates and where nobody looks.
Do not lubricate the running surface of the track. Oil or grease in a track turns garden dust into grinding paste, which is the opposite of the intention. The track should be clean and dry.
Drainage slots
Along the bottom of the threshold there are drainage slots, usually with small covers. Their job is to let out any water that gets past the outer seal. They block with leaf litter and silt, and when they block, water sits inside the profile.
Check them every autumn and again after any storm that dropped a lot of leaves. A thin brush or a jet of water clears them. Then pour a jug of water along the outside of the threshold and watch it drain. If it pools, something is blocked.
A set in Broxbourne that had been letting water in for two winters turned out to have every drainage slot packed solid with silt washed off a gravel path. Twenty minutes with a brush fixed what two visits from two different installers had not diagnosed, because nobody had looked.
Hinges and running gear
Moving parts want a light application of a suitable lubricant once or twice a year. A dry PTFE or a light silicone spray is generally the right choice for door and window hardware. Apply sparingly to the moving joints and wipe away the excess — excess lubricant attracts dust.
What not to use, and this is worth being firm about:
- General-purpose water-dispersant sprays. They wash out the manufacturer's grease, work briefly, and leave the hardware drier than before.
- Heavy oil or grease anywhere near the track.
- Anything petroleum-based on rubber gaskets. It degrades them.
If your fabricator specified a particular product, use that. Hardware manufacturers do publish requirements, and using the wrong thing can matter for a warranty claim.
Gaskets and seals
The rubber seals do the weatherproofing, and they last well as long as they stay flexible and stay in their grooves. Wipe them with a damp cloth when you do the tracks, and once a year treat them with a silicone-based rubber conditioner — not an oil.
Look for gaskets that have pulled out of the groove at a corner, gone flat and hard, or torn. All three are cheap to replace and expensive to ignore, because a failed gasket at a corner is exactly where water finds its way in.
The powder coating
Powder coat is durable but it is a coating, and it wears if you attack it. Wash it with warm water and a mild household detergent, using a soft cloth. Rinse and dry.
Never use solvents, abrasive creams, scouring pads or pressure washers close to the frame. Along the North Circular and the busier stretches of the A10, urban grime builds up faster than people expect and twice a year becomes three times a year — but the method is the same. On matt finishes, wipe in one direction rather than in circles; circular polishing shows up under low sun.
If you also have Schüco windows in the same coating batch, do them at the same time with the same cloths. It keeps the ageing even across the elevation, which matters more than it sounds when the sun is low in the afternoon.
Seasonal movement
Aluminium expands. A door that runs perfectly in January and catches slightly in July is behaving normally, and a competent installer will have set the adjustment with that in mind. A door that catches badly, or that has clearly dropped so the shadow gaps are uneven, needs adjusting rather than forcing.
Resist the urge to adjust the hinges yourself. The adjustment points on folding gear interact — move one and you change two others — and a set that has been enthusiastically fiddled with is more expensive to put right than one that was simply left alone.
When to call someone
- Water inside after rain, once you have confirmed the drainage slots are clear
- A leaf that has dropped visibly, with uneven shadow gaps
- A handle that needs force, or a lock that will not throw without lifting the door
- Any grinding or crunching from the running gear — stop using the door and call
- Misting between the panes of a sealed unit, which means the unit has failed and is usually covered by warranty
Keep the paperwork from installation somewhere findable. Warranty claims go much faster when you can quote an order number and a date.
Common questions
How often should bifold doors be serviced?
A twenty-minute clean and check twice a year covers most of it. Some installers offer a paid service visit every couple of years, which is worth it on large or heavily used sets.
Can I use WD-40 on bifold door hinges?
Better not to. General-purpose water-dispersant sprays wash out the factory grease and leave the hardware drier than before. Use a dry PTFE or light silicone lubricant, or whatever your fabricator specifies.
Why do my doors stick in summer?
Aluminium expands with heat, so a small amount of seasonal change is normal. Significant sticking usually means the gear needs adjusting, or something has moved beneath the threshold.
Can I pressure wash aluminium doors?
Avoid it near the frame and seals. Warm water, mild detergent and a soft cloth is the correct method; pressure washing can force water past seals and damage the coating.