How to Adjust External Bifold Doors
Being able to make subtle or major adjustments (depending on the circumstances) to your external bifold doors can be an incredibly useful skill to have in your inventory, especially if your house is prone to unwanted movements, which will be particularly likely if you like in an area afflicted by harsh or diverse climates. It can be a simple case of moving your doors a little to the left, a little to the right, raising them a little bit or a lowering then a little bit, but even this is something that requires prior knowledge of exactly how bifold doors work, as it's certainly not a job you want bodge, as this will leave your home exposed. What specific adjustments you'll need to make will depend on not only your specific doors and their configuration, but the problem that caused them to unsettle.
The ease with which you will be able to make any adjustments, minor or major, to your external bifolding doors will depend on the age of the doors and how damaged they are, if at-all. Being external doors, they will have been exposed to the elements for any number of months or years, and in that time they will undoubtedly have worn a little. This will be especially true if your doors and their frames are made from cheaper materials like UPVC. It's not only the weather that will wear your doors and their tracking hardware either, as heavy use will degrade them over time, especially if you haven't kept on top of the up-keep. If your doors appear to be damaged to the extent that they are practically falling out of their tracks, you might want to consider simply replacing them. If they are in decent enough condition, however, you should be all set to make the adjustments you need.
Left, Right Raised or Lowered?
The first thing you'll need to do is actually play with the door a little and see where the problem is. If your lead bifold door (the one you pull on to move the other doors) appears to bind to the jamb or isn't set properly with the opening, then it might need to be adjusted to the left or right in order to free up the other doors. In order to do this you're going to need to adjust the hinges fixed to the sill, which can be done in most cases with a simple, good old-fashioned allen key (hex key, allen wrench, whatever you want to call it). Above these hinges in the top track there should also be some similar hardware that will also be adjustable with your allen key. Experiment here, sliding your doors until they are flush and comfortable. If your bifold doors are dragging however, and appear to be sitting a little low or are sometimes popping out of their track when you use the door, you can adjust the height using the hinge bolts until they stay in place, extending it to raise the doors and pushing it in to lower them. Of course, the specific construction of your bifold doors will vary depending on make, model, material and manufacturer, but generally, these tips will hold true.
If you want to make more intricate adjustments, such as fixing specific panels or panes, sanding, painting or changing the hardware of your bifold doors, you're going to need to know how to remove them from their tracks and put them back in their tracks. In many cases it should simply be a case of popping them out of the track by popping the spring-loaded pin on the edge of the door. This may require a fair amount of force (be careful), but if you push down hard enough your doors should basically pop right out. The important thing is not to be alarmed when this happened, and to be ready for it! Once your doors are out and placed somewhere safe and sensible, you should be free to clear the tracks of any debris that might have caused the bifold doors to jam and closer inspect the doors themselves. There is a chance that the hardware will need a little lubrication (WD40 is your friend here) or simply a little soap and water. The doors, meanwhile, could have worn or warped (especially possible if they are of a wood construction) and might require some sanding or filling. Either way, when you are ready to place your doors back into their tracks, the process couldn't be simpler. If the problem is with the frame, however, and not the doors themselves, you might need to tighten the screws that fix it to your opening.
If you've tried all the steps above and a simple adjustment and clean up job won't do the trick, then you might need to make some minor repairs. If your doors are loose and wobbly, and you can't get them to align using the tips above, it could be because the bottom pin has worn out of its seat within the door. In this case you'll need to remove it and reposition it, filling in the now departed hole with some filler. Drill a new hole and fix the pin once again, though make sure the new hole is far enough away from the old one that they don't meet. If this doesn't work then there's a chance you might actually need to replace the pin itself.
To summarise, making minor adjustments to your bifold doors can be a relatively straightforward job if you have the right tools, the right mindset and a certain amount of patience. Remember to read the situation, make your adjustments bit by bit until you're happy with the results and don't be afraid to remove your doors entirely if needs be (they really are not that difficult to rehang).