While very different in almost every way, these two types of doors share one major thing in common: They both use large amounts of glass and they both open wide!
This article hopefully will help you navigate the main features for each and compare the key differences. By the end of it, you should have a solid understanding as to which one works best for your particular project. We will even touch a bit on costs.
Bi-Fold – Although commonly used in reference to a style of patio door, it is technically incorrect. Anything “bi-fold” is technically two, and no more than two door sashes hinged together. The only time it is correct to identify a patio door system as a “bi-fold” door is when it is truly a two-panel system. Regardless, it is a term that stuck and is widely accepted.
Other terms used: Folding doors, multi-fold doors, concertina doors, or accordion doors.
Multi-Slide – Unlike folding doors, sliding doors come in a variety of versions and their respective names are used to differentiate them all. For example, sliding doors, multi-slide, and Lift & Slide doors are all technically doors that slide on a track, but they all refer to very specific products.
This particular article focuses primarily on Multi-Slide, as this is more comparable in terms of purpose and function to folding doors.
Note: Both bi-fold doors and multi-slide doors can be described as “moving glass walls”.
Aside from the obvious function of hinged sashes folding into an open position, most folding doors in the USA roll on a top-hung track primarily. The main benefit is in the operation itself. Not only do top hung folding doors glide and move with a very fluid movement, there is also little maintenance involved to keep debris out of the track. However, anyone planning for a folding door system would need to give careful consideration to the structural design. There is a significant amount of weight that would need to be supported sufficiently from the top. Skipping or ignoring this step would almost certainly lead to problems. This is a big reason why some say Bi-Fold doors are “finicky” or “problematic” when in reality the problem exists in the lack of preparation and proper installation.
Unlike folding door systems, most sliding doors (of all types) in the USA are bottom rolling. The roller mechanisms are located inside the bottom of each panel and they simply glide along the supporting track. These mechanisms can support a significant amount of weight and is why you will typically see much wider sized panels with sliding doors. One obvious drawback is the the need to frequently clean the bottom tracks from debris to keep them running smoothly. Additionally, though robust, one can expect some wear and tear on the tracks, wheels, and weather seals over time. It is good practice to lubricate the tracks as part of the regular maintenance intervals. It is notable that many of the rollers themselves do not need additional lubrication.
Maximum Opening Capabilities
Unless specifically designed into the system, bi-fold doors do not have a fixed panel. This allows all panels to fold and stack together and maximize the total open space.
In many cases, if not most, multi-slides have at least one fixed panel. When the door slides open, they will stack adjacent to the fixed panel like a stack of cards. When calculating the total open space with a multi-slide door, subtract the total width of the fixed panel.
Because total space in the opening is lost due to a fixed panel, many consider that a drawback and may give more consideration to a folding door system. However, the exception being the possibility of pocketing the sliding door completely into the structure itself. In this case, a multi-slide door would be the clear winner because there would be 100% gain in the total opening.
Individual panel sizes usually max at about 4 feet wide by 13 feet heigh.
Individual panel sizes usually max at 6 feet wide by 12 feet heigh.
To truly compare expenses between products you have to navigate not only the cost of the product itself but also any additional factors that one product might incur over the other, such as additional construction.
Typically when it comes to the product itself, a bi-fold door system could range anywhere from $700 – $1600 per linear foot. Every manufacturer has their own pricing structure and so do the dealers who market and install the products.
Top-loading folding doors may incur construction costs to insure proper structural support.
Like bi-fold doors, prices can very significantly. However, you might find that a multi-slide door is priced slightly lower. Wider panel possibilities might require fewer panels to fill your project’s rough opening. There is also less hardware required to make the door function. This all contributes to a reduction in cost.
However, sliding doors that completely slide into a pocket cavity will require additional construction costs. The cost of doing so may be more expensive than utilizing the benefits of a folding door system for similar results.
As you can see, one type of door system does not necessarily trump the other. In the end, the better choice is the one that makes the most sense after weighing all of the above with your particular project in mind and with what you are ultimately trying to achieve.