How folding glass doors work

A folding door, often called a bi-fold, is a series of hinged glass panels that run on a track and fold against each other like an accordion. When open, the panels stack neatly at one or both ends of the opening, leaving almost the full width clear. That is the main difference from a sliding door: a stacking slider always leaves some panels standing in the opening, while a folding door gets nearly all of the glass out of the way. Impact folding doors use laminated glass and are tested as a complete system, so the open-air feel comes with hurricane protection when they are closed.

Panel stacking and layouts

• Single-direction stack: all panels fold to one side. Best when one end of the opening is next to a wall and the other faces the main view.
• Split stack: panels fold to both sides, opening from the middle. Good for very wide openings and symmetrical rooms.
• Traffic door: many layouts include one panel that swings on its own like a regular door, so you can step outside without folding the whole wall.
• In-fold or out-fold: stacked panels sit inside or outside the room. Out-folding keeps interior space clear; in-folding keeps the patio clear.

Opening widths and approvals

The overall width of a folding door comes from the number of panels and the width of each panel. Each impact-rated system is approved at specific maximum panel sizes and design pressures, so a wide opening is laid out panel by panel against the approval. Taller panels and higher-pressure openings, such as those facing open water, can mean narrower panels or a heavier system. We also check the header above the opening, since it has to carry the load without deflecting onto the track.

In Broward County, part of the High-Velocity Hurricane Zone, the door must be approved for HVHZ use, typically shown with a Miami-Dade NOA. In Palm Beach County, a Florida Product Approval or Miami-Dade NOA is accepted, and each opening must meet its required design pressure. We handle the permit and inspections.

Threshold options

The threshold decides how the floor reads from inside to out and how the door handles water. A raised sill sits on the slab and generally offers stronger water resistance, which matters on exposed elevations. A low-profile or recessed threshold sits closer to or flush with the floor for a continuous surface onto the terrace, but it needs the slab detailed for it, a drainage plan, and an approval that covers that configuration. A covered patio or deep overhang helps the low-threshold option perform. We review both with you before the slab is poured or the order is placed.

Pool decks and terraces

Folding doors are a natural fit for a family room that opens to the pool or a terrace used for entertaining. Salt and chlorine exposure affect finish and hardware choices, and the folded stack should land where it does not block a walkway. On condo terraces, association approval is usually required in addition to the permit. We coordinate both and track the work in your client portal.

Brands and related doors

We install folding systems from ES Windows, PGT, CWS, ETI, and Velocity, where a product line fits the opening. If a folding door is not the best fit, compare sliding glass doors, including pocketing sliders, or French doors for smaller openings. See all impact doors, plus pivot and entry doors, and matching impact windows. We serve Fort Lauderdale, Lighthouse Point, Pompano Beach, Delray Beach, Palm Beach, and our other service areas.

Folding door questions

Folding or sliding: which opens wider?

A folding door clears nearly the full opening because the panels fold into a compact stack. A stacking slider leaves its stacked panels in the opening unless it pockets into the wall.

Are impact folding doors approved for hurricane zones?

Approved systems are available, each within its listed panel sizes and design pressures. In Broward the product must be approved for HVHZ use. We confirm the approval for your opening before ordering.

Can I get a flush threshold?

Many systems offer a low-profile option. It needs the right slab detail and drainage, and the approval must cover that threshold. A raised sill is the safer choice on exposed elevations.