If you’ve been considering installing a set of folding doors in your home or office space, then you may have noticed that many manufacturers offer both interior and exterior folding door systems. Although they all work using the same technology (folding panels that move along a metal track using rollers), there are a few key differences between exterior and interior systems.

The other day, a reader asked whether or not it’s possible to put exterior folding doors inside, so we decided that we’d put together a brief post explaining our answer and breaking down some of the key differences between interior and exterior systems.

Technically speaking, there’s no reason why you can’t install exterior folding doors on an interior structure. While it doesn’t make sense for most situations, there are a few cases (such as for commercial use) where a customer could benefit from installing exterior folding doors inside.

What’s The Difference Between Interior And Exterior Folding Doors?

As we mentioned, both interior folding doors and exterior folding doors use the same exact technology. All multi-fold door systems consist of a few main components:

• At least 3 door panels linked together with hinges.
• A single swinging door (one of the panels) that acts as a regular entry/exit when the system is closed.
• Doors move along rollers that are inset into tracks using pins.

The main difference between interior and exterior folding door systems is the strength and durability of the door materials.

Overall, interior systems are far lighter-weight as they aren’t designed to withstand the outside elements. Door tracks are typically smaller, locks are smaller, and the glass is thinner. For this reason, interior doors are usually more cost-effective if you plan on installing folding doors inside of an office, retail space, or showroom.

However, as we mentioned, there are several cases where somebody might want to install an exterior door system inside, such as:

• For a hybrid indoor-outdoor space (hotels, enclosed patios, outdoor shopping mall).
• Increased security (vehicle showrooms, high-end retail stores, clubs/restaurants).

That being said, here are the key differences between exterior and interior folding door systems.

Glass Thickness

The first thing that you’ll notice is that interior folding doors are a lot lighter than exterior door panels. This is mostly due to the thickness of the glass used within the doorframe. Interior doors typically only use a single pane of tempered glass, whereas exterior doors usually use 2 or 3 panes of glass.

The more panes of glass are in a system the more thermally efficient it is and the more resistant it is to heavy winds, storms, flooding, and other exterior forces that could break down a thinner pane of glass. Interior setups typically don’t need to be as strong and therefore aren’t designed to be as strong.

Doorframe Material

Most interior folding door systems are made using a thin, lightweight aluminum doorframe. These are easy to install, relatively maintenance-free, and can stand up to regular daily use. Exterior folding doors, on the other hand, usually offer greater options when it comes to doorframe materials.

With an exterior doorframe, you’ll typically be able to choose between:

• Reinforced aluminum.
• Natural hardwood.
• Vinyl/PVC.
• Hybrid aluminum-vinyl or aluminum-wood doorframe.

Thermal Efficiency

Interior folding door systems have very little in the way of energy-efficient coating or treatment. After all, they’re located indoors, where the temperature is expected to remain the same everywhere in the building.

Exterior folding doors typically feature two types of technology to increase thermal efficiency:

• Thermal breaking throughout the doorframe.
• Low-E (low-emissivity) glass that resists temperature change from one side to the other.

Exterior folding door systems are able to keep the inside of your home a cool 70-degrees even while it’s a sweltering 105-degrees outside. This is due to the fact that low-E glass is infused with Argon gas to resist temperature change and thermally-resistant polymer breaks line the inside of the doorframe itself.

Interior folding doors contain little to no thermal breaking and definitely don’t have low-E glass.

Security

Interior folding door systems typically have a simple cylinder lock that’s designed to keep the doorway closed and secure when it’s not in use. However, exterior folding door systems usually feature multi-point locking systems and reinforced shatter-proof glass that are designed to protect against theft, vandalism, and burglary.

Installing Exterior Folding Doors Inside

Overall, you should have no problems installing an exterior folding door system within a home, office, or other business space. Since the door panels will be heavier, you may need to reinforce the structure, and you’ll have to use heavier-duty rolling tracks. But these are all things that your builder or contractor can help you work through.

What’s The Advantage Of Using An Exterior Doorway On An Interior?

Generally speaking, exterior folding doors aren’t commonly installed inside residential spaces. However, they are installed inside of commercial spaces quite frequently. In fact, many commercial folding door systems that are used within clubs, retail spaces, hotels, and showrooms are designed with many of the same features as residential exterior doors.