Top hung systems: As the name suggests these are hung from a track above. They require a steel lintel to take the weight of the doors. With no track at the bottom, these offer a level threshold that won’t trap dirt or debris.

Bottom rolling systems: These move on floor-mounted tracks – a good choice where it isn’t possible to have a steel lintel above.

Access doors: If the area with bi-fold doors needs regular access then a single panel access door that can be opened independently of the bi-fold should be specified.

Inwards or outwards hung: This indicates where the doors will stack in relation to the threshold once open. Inwards hung will stack internally and outwards externally – which is usually what people choose to save internal space. You can get half-in-half-out options too, but these are the best (and worst) of both worlds so ask for visualizations of each.