The filigree width of the aluminium profiles emphasizes the minimalistic design of Keller minimal windows®. The frame profile is reduced to a minimum to allow seamless integration into floor, ceiling and walls. A glass proportion of up to 98% guarantees unhindered light flow only interrupted by slender 21 or 26/34mm leaf profiles.

The border between indoors and outdoors dissolves. Up to four-track sliding systems in combination with fixed leaves, interior or exterior corners with no distracting posts, large, telescopic-like opening variants are possible.


Combining outer frames perfectly set into the floor with an integrated sliding rail, minimal windows® offer a barely perceptible, barrier-free threshold transition that couldn't be more different from conventional systems with surface-mounted door frames or deep thresholds. The transition from indoors to outdoors is seamless.

The new minimal windows® freeway is distinguished by a sliding rail raised to floor level. This offers a virtually even transition.


Sliding doors up to 12 m² and fixed windows of up to 18 m² can be achieved. The maximum overall height for sliding doors is 4.5 m. Larger overall heights (up to 6 m) with even more impressive views are available upon enquiry.

The most diverse arrangements of sliding leaves, pivoting doors and fixed elements in different tracks create the most exclusive, individual solutions – even with bent systems. The "pocket" system enables the sliding leaf to slide and completely disappear inside the wall.
Countless colours and the most diverse surface structures can be selected.

Arrangement variants (PDF)

Energy efficient

minimal windows® sliding systems achieve maximum energy efficiency through the optimised thermal insulation of the profiles and the use of large thermal insulation glazing.
There is a choice of double or triple glazing or, for cold systems, single glazing.

According to the overall size, the minimal windows®4+ systems with triple glazing achieve insulation values at passive house level with Uw-values of ≥ 0.70 W/m²K.


Extremely powerful electric motors with tensile forces of 800 kg (LLD24), 1.500 kg (LLD36) and 2.400 kg (LLD36x2) move the sliding leaves silently via toothed belts. Various controllers are available for optimum user comfort.

Our in-house test system consists of a telescopic-like variant S-S-S with leaf dimensions of 3,100 x 4,000mm (W x H) each and a leaf weight of 993kg each. After more than 40,000 faultless movement cycles, neither roller carriages nor sliding rails show any signs of wear.


Deciding on Keller minimal windows® means deciding on highest quality. Security corresponding to a burglar resistance of RC 2 (WK 2) is fulfilled for all minimal windows® sliding series.
Bullet-proof versions are available on enquiry.
minimal windows®4+ offers sound reduction values up to 43 dB (minimal windows® up to 39 dB).

A design without corner posts is possible for all series.
Unparalleled top performance with respect to wind load, driving rain tightness and air permeability is achieved.
Suitable for blower-door test.
Typhoon and hurricane resistance on enquiry.

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