The following diagrams show a side on view of typical Bi-folding doors. The last pictures show the style of bi-fold we would recommend.
BOLT ON TRACK - TRACK INSIDE HOUSE
Panels roll on a track that is "bolted on" to the outer frame.
Door has untidy appearance
Door has a high threshold - meaning you need to step over it
Door has large front-back measurement making them look bulky
Generally not recommended; OK in some situations
BOLT ON TRACK - TRACK OUTSIDE OF HOUSE
If a door that is designed for open-in is fitted turned around, then the track is exposed to weather and the dirt build up will prevent the doors from operating correctly.
Door will not operate smoothly
Door has untidy appearance
Door has a high threshold - meaning you need to step over it
Door has large front-back measurement making them look bulky
NOT recommended
CONCEALED TRACK (STANDARD THRESHOLD) ON ALUMINIUM BI-FOLDING DOORS
Aluminium Bi-folds can have a concealed track. This has many advantages including:
Track cannot be removed - highly secure
The doors have a clean, smooth appearance as there are not extra "bolt-ons" (see how the vertical lines of the sash line up with the verticals of the outer frame).
Standard threshold (pictured) provides optimal weather performance.
Standard threshold (pictured) with open-out doors gives it further security as doors rest against up stand when pushed from the outside.
A low threshold is also available for flush fitting.
Recommended
CONCEALED TRACK (LOW THRESHOLD) ON ALUMINIUM BI-FOLDING DOORS
Aluminium Bi-folds can have a concealed track. This has many advantages including:
Track cannot be removed - highly secure
The doors have a clean, smooth appearance as there are not extra "bolt-on's" (see how the vertical lines of the sash line up with the verticals of the outer frame).
With the low threshold (pictured) there is minimal step-over required.
Recommended
Note: - above drawings have been modified to improve clarity and are not exact representations of the systems - but are similar.
