The Design Behind Folding Patio Doors

The Design Behind Folding Patio Doors

Folding Patio Door Configuration Options 

Weathertight Folding Door

At Brennan, we know that one size never fits all when it comes to home improvement, which is why we take a consultative approach to every project. If you're looking for advice on installing patio doors for your home contact us today!

Folding patio doors have become a hot ticket item for our company. We've received inquiries on a daily basis about the accordion doors. The typical request is from a homeowner looking to replace existing sliding patio doors with a fresher, more appealing alternative. The functionality and aesthetic appeal of the folding doors often catches their eye.

When deciding on a patio door replacement, keep in mind the following configuration options. Folding patio doors may or may not be the best option for your door replacement.


Are you looking to divide rooms within the interior of your home? Interior applications are well suited for either an inswing or an outswing application. If this is a retro-fit application, be aware of the threshhold requirements from the folding door manufacturer.


Exterior folding patio doors are best suited for an outswing application. Here is a recent job-site photo of a residential folding patio door. These panels are 3' wide by 8' tall and were used to enclose a patio. This application required use of James Hardie® to fill in the space surrounding the doors, as well as insulation between the doors and behind the HardiePlank® lap siding to ensure the interior temperature would remain relatively stable.

Weathertight Folding Doors

Consider Functionality

Most configurations have an active door, identified by the handle. This door serves as a passage door so this should be in the most convenient location. Typically, your active door will be an odd numbered panel. For instance, the active door for the project pictured, is the third door from the left.

How Many Doors

The least expensive options use fewer doors and standard sizes. For example, a 18' wide system can have 6 - 36" wide doors or 9 - 24" wide doors. The 6 door system will be less expensive than the 9 door system.

Door Configurations

Rough Opening Heights:

  • 6/8 - 85"
  • 8/0 - 101"
  • 10/0 - 125"

Folding Door Options

We offer multiple door options to match the personal style of your home.

  • Fir
  • Aluminum Clad
  • Custom Series - Mahogany, Alder, Red Oak and others

Folding Door Glass

Our glass is insulated Low E. Here is the energy values according to door type.

U-Values and Solar Heat Gain values will be affected by the type of door panel chosen for the system. A chart with these values per door panel type is below:

Door Panel Type


Solar Heat Gain

Fir Door






Aluminum Clad



Custom Wood



Aluminum Clad and Custom Wood are being shipped with Cardinal 366 Low E insulated glass. Other glass types are available upon request in these two door types (additional charges may apply to special request glass types).

Folding Door Frames

For interior and exterior applications, we offer an aluminum frame and wood frame.

Aluminum Frame Notes

Maintenance Free: Due to the heavy gauge aluminum extrustion and powder coated finish, the exterior is virtually maintenance free.

Self Trimming: Our folding patio doors do not needs any exterior trim such as brick mold.

Minimum Wall Thickness: A 2x6 stud wall thickness is required to install a folding patio door. For 2x4 walls the wood frame must be used.

Interior Options: Pine, Oak, Mahogany, and alder are available. Also, a PVC substitute can be requested for high moisture areas.

Exterior Option: Bronze and what are standard, but custom colors using an epoxy based marine finish are also available.

Wood Frame Notes

Interior Options: Poplar, Mahogany and Alder.

Not Self Trimming: Exterior trim is required for the wood frames; the trim is supplied by the inallation company or homeowner.

Minimum Wall Thickness: Available for either 2x6 or 2x4 wall thickness. Wider widths are available at additional charges.

Folding Patio Doors Thresholds


Weather Strip

Weather Resistance

Swing Type

Weathertight Threshold

Foam Compression

Water & Wind Resistance


Low Rise Threshold

3/8" Nylon Brush

Moderate Wind Resistance

In or Out-swing

In Floor Track

3/8" Nylon Brush

Low Wind Resistance

In or Out-swing

ADA Threshold

3/8" Nylon Brush

Low Wind Resistance

In or Out-swing


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