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Top-hung vs. bottom-rolling bi-fold doors: what's the difference?

All bi-fold doors run along tracks in the top and bottom of the frame. But some doors are top-hung, while others are bottom-rolling. What does this mean?

Top-hung vs. bottom-rolling bi-fold doors—a comparison

Top-hung bi-fold doorsBottom-rolling bi-fold doors

Ease of use

With top-hung bi-folds, all the weight is at the top of the frame. Without the right set of captive rollers, the doors can be unstable.

Bottom-rolling doors have a lower center of gravity and don’t pull down as much weight from the top of the frame. This gives them a smoother operation and makes them more stable than top-hung bi-folds.

Ease of installation

Top-hung bi-folds need a strong lintel or beam overhead to bear the weight of the wall or roof above.

The lower balancing of their weight means bottom-rolling bi-folds are easier to install than top-hung doors.

Look

Both top-hung and bottom-rolling bi-folds are available in a wide range of materials, colors and styles, and are engineered to complement the most contemporary home designs.

Maintenance

Top-hung bi-fold doors do have a bottom guide track in which dirt, leaves and debris can accumulate. However, this is less likely to affect the sliding motion of the doors.

We have more information on bi-fold door maintenance here.

When the doors are open, dirt, leaves and debris can sometimes get stuck in the bottom track, affecting the doors’ sliding motion.

Go here for more information on bi-fold door maintenance.

What are top-hung bi-fold doors?

Top-hung (also known as top-track) bi-fold doors are so called because they ‘hang’ from the top track, using the bottom track as a guide only.

This means that the frame heads take most of the doors’ weight and so need to be supported by a strong lintel. The lintel must be able to bear both the weight of the doors and the weight of the wall or roof above them.

While top-hung bi-folds can sometimes be unstable, using a component known as captive rollers to ‘hang’ them can solve this problem.

What are bottom-rolling bi-fold doors?

Bottom-rolling (also known as bottom-track) bi-fold doors run along a bottom track, meaning most of their weight is concentrated at the foot of the door and not supported by any overhead beams or lintels. This makes the doors more stable and reliable and gives them a smoother operation.

Do bi-fold doors need a bottom track?

Technically, no—installing bi-fold doors without a bottom track is possible, and it’s often done with doors made from wood or plastic, or internal bi-fold doors.

However, bottom tracks are typically used on steel or aluminum external bi-fold doors, due to the:

  • increased weight, not only from the metal but the double-glazed glass
  • size of the apertures
  • additional guidance that the track offers when the doors are opened and folded back

One important benefit of a bottom track is that it heavily contributes to keeping weather out. There’s more information on weatherproofing and door thresholds here.

Both sets of tracks are really only there as a guide and to offer structural strength, as the doors use pins at the top and bottom to carry the weight and as hinges.

That said, trackless bi-fold doors generally aren’t available.

Are Origin Bi-Fold Doors top-hung or bottom-rolling?

All Origin Bi-Fold Doors are bottom-rolling and use a specially engineered trolley system that makes opening the doors smooth, simple and silent. The design and engineering features of our bi-fold doors are explained in more detail here.

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