In general terms there are only 2 alternatives – doors that swing and doors that slide.
A very popular type is the French Door which is usually seen as a double set, hinged at the sides and locking in the middle. They can be fitted to open out or in which, for rooms with limited interior space, is useful as the outward opening option does not interfere with your room itself. You should bear in mind what you are doing with the area immediately outside the doors if you select outward opening models.
For larger openings French Doors will need either side or top panels or, if the opening is wide enough, you could fit 2 sets separated by a glazed or solid panel.
Tilting & Turning doors also offer the option to open in or out, but the standard construction is to open them inward, which can be annoying in wet weather if the water drips off the doors onto your interior floor.
Tilt & Slide versions move along the tracks like a typical sliding patio door and so do not interfere with interior or exterior space. The disadvantage is that the moving door will overlap one of the other panels and so you will only have a 50% clear opening for a 2 panel set of doors, even if both panels move – but usually one is fixed into place and does not move.
Both tilting & sliding types of doors tend to have high thresholds and can be awkward to use for wheelchairs.
Similar to the Tilt & Slide, a standard sliding door will be fixed into tracks and move from side to side. The benefits are non interference with interior or exterior space, but the downside is that the overall clear opening will be restricted due to the door remaining in the tracks. For sets of 3, 4 or more doors you can opt for more than one panel to slide.
Bi-fold doors offer the largest clear opening & flexibility. When opened they “stack” neatly to the side of the opening and can be installed to be folded to inside or outside. Moving on tracks they can be “top hung” or “bottom hung”, They are very often fitted with floor level “flush” thresholds which are great for ease of access.
Double or triple glazed units for glass doors should be used in order to maximise energy efficiency. In terms of safety & security, for installations where glazing reaches floor level the glazing should be toughened or laminated to meet with building regulations and lower the risk of breakage – especially when young children are in residence.
Most modern examples are fitted with multiple point locking systems, anti-lifting tracks &locks that resist picking, bumping or drilling.