Bi-Fold Lift-Up and Up-and-Over Flap Fittings Defined

Bi-fold lift-up flap fittings and up-and-over flap fittings are specialised flap mechanisms for wall units. Whilst a bi-fold lift-up flap folds a two-part front upwards in the centre when opening, the up-and-over flap pivots a single-piece front completely above the cabinet carcase. Both systems require precisely calculated lift mechanisms to hold the weight continuously in any open position.

What Exactly Are Bi-Fold Lift-Up and Up-and-Over Flap Fittings?

In modern furniture construction, flap systems increasingly replace traditional hinged doors on wall cabinets. Similar to a vehicle's tailgate, they lift the furniture fronts entirely out of the user's movement and head clearance zone. The technical heart of these systems is the lift mechanism – a lever assembly that is frequently supported by a gas strut or a spring pack.

The bi-fold lift-up flap is used on tall wall units. The front is split horizontally. An upper concealed hinge connects the upper front to the carcase, whilst an intermediate hinge connects both front sections. When opened, the system folds upwards together. Space requirement above the cabinet is minimal.

The up-and-over flap moves a large, single-piece front in an arced motion over the top of the cabinet. This requires sufficient clearance to the ceiling. The fitting ensures that the front pivots upwards parallel to the carcase.

Types and Variants of the Mechanism

The choice of mechanism depends on the weight and dimensions of the front.

• Mechanical spring mechanisms: Operate purely via adjustable steel springs.
• Gas-operated systems: Utilise sealed cylinders in which compressed gas performs the lifting work. Classic Gas Struts lift the flap smoothly.
• Heavy-duty systems: Reinforced lever arms are utilised for fronts made of solid wood or thick MDF. Here, the fitter relies on Gas Struts for Heavy Flaps.
• Basic stays: For small, lightweight flaps, basic Flap Stays often suffice, simply locking the front in the end position.

Visually, the fitting components are matched to the cabinet interior. In addition to plastic cover caps, colour-matched cylinders are used directly, such as the Gas Strut Black for dark carcases or the Gas Strut Silver for technical designs.

Dimensions, Standards, and Typical Values

Exact calculations are strictly required for correct installation and function. The fittings are dimensioned according to the power factor (PF). This is calculated from the carcase height multiplied by the front weight including the handle.

• Carcase heights: Bi-fold lift-up flaps are typically suitable for heights of 480 mm - 1040 mm. Up-and-over flaps are usually installed with heights of 350 mm - 800 mm.
• Carcase widths: Up to 1800 mm are possible with appropriate material (taking deflection into account).
• Push-out force: Specified in Newtons (N) for gas struts. Common values range from 50 N for light flaps to over 500 N for heavy fronts.
• Drilling pattern: Fixing to the carcase is almost always carried out using the standardised System 32 with a 5 mm drill hole diameter.

Application and Selection

Planning a flap cabinet starts with determining the front weight. A 19 mm thick chipboard panel weighs approximately 13 kg per square metre. Once the weight is determined, the appropriate lift mechanism is selected from the range of Flap Fittings.

A crucial criterion during installation is the kinematics. The fittings must be positioned exactly according to the manufacturer's specifications, as deviations of just a few millimetres will impair the closing action. Most modern systems feature integrated damping (soft-close), which prevents slamming during closure. This function must not be confused with mechanical push latches (push-to-open), which are used for handleless fronts and allow the flap to pop open a crack when the front is pressed.

Related Terms

• Power factor: Key figure used to determine the required spring or lifting force.
• Intermediate hinge: Specialised hinge connecting the two front sections of a bi-fold flap.
• Concealed hinge: Cup hinge, usually with a 35 mm cup drilling, for attaching the upper front to the carcase top panel.
• Gas strut: Pneumatic component used for power-assisted lifting.

Matching Categories

• Flap Fittings
• Gas Struts for Heavy Flaps
• Flap Stays
• Gas Struts
• Gas Strut White