A month ago your renovation was completed. On delivery day, your brand-new balcony door opened and closed with a single finger. Today, however, the bottom edge drags on the threshold, and turning the handle all the way down takes real effort.
Your first thought: "They installed faulty windows!" Relax. In 99% of cases, there is no permanent damage - just a phenomenon called "sagging". Let's look at the 3 reasons it happens and why the fix is often a matter of minutes.
The most common reason a sash sags has nothing to do with the hinges - it's the glass itself! Imagine the opening sash as an empty, lightweight aluminium "picture frame". Inside it sits a triple-glazed unit weighing 80 to 120 kg.
The glass doesn't rest directly on the aluminium (it would crack). Specialised hard plastic packers called glazing shims are placed around the perimeter. They must sit diagonally to transfer the weight to the bottom hinge. If the factory technician rushed or used soft shims that compressed during the first month's use, the geometry shifts. The side opposite the hinge "drops" a few millimetres and the sash drags on the floor.
The technician removes the glazing beads (which hold the glass), inserts a new shim of the correct hardness to lift the pane, and the sash returns to perfect alignment. This work is done at your home in 15-20 minutes per sash, without dismantling anything from the wall.
Especially in newly built properties, the materials (concrete, bricks, renders) carry enormous weight and contain trapped moisture. During the first months after construction, the building "settles" - shifting imperceptibly, on a millimetre scale.
This micro-movement transfers to the window frame. Even if the installer laser-levelled the window perfectly on day one, a 2 mm wall shift is enough to knock the locking mechanisms (mushroom cams) out of alignment. The result: the handle jams, the sashes don't seal airtight, and you hear air whistling through.
Settlement is usually complete within the first year. That is why reputable installation companies include a free micro-adjustment within the first 6 months as part of their warranty - they know buildings "move".
Modern, heavy energy-rated windows have a break-in period - exactly like a new car. This is not a defect but a natural property of the materials.
If you installed dark aluminium in winter (5°C) and the following month temperatures hit 25°C, the metal expanded. This volume change can make the window "catch" at the locking points. Dark colours (RAL 7016, anthracite, black) reach outer surface temperatures of 70-80°C in direct sunlight.
Despite their top-tier durability, modern perimeter locking mechanisms "take up their clearances" after 100-200 open-close cycles. This is perfectly normal: the metal components "bed in" to their final positions within a few weeks of use.
The golden rule when a window sticks: DON'T FORCE IT! If the handle won't turn all the way down, don't hang off it with all your weight. The perimeter mechanisms have gears (rack-and-pinion) - if they jam and you force them, you'll break the mechanism and the repair is costly.
All modern hardware (GU, Roto, Maco, Siegenia etc.) is adjustable in 3 dimensions (3D). A specialist uses a simple Allen key (4 mm) to adjust the top and bottom hinges: raising or lowering the sash, shifting it left/right, or pressing it more firmly against the gasket. An entire home can be adjusted in 15-30 minutes.
Contact your installer immediately. Reputable companies always include a free inspection and micro-adjustment in the first 6 months as part of their warranty. They know that heavy sashes with triple glazing need this final "tuning" once clearances develop. If your installer refuses a free adjustment, you may need to reconsider your partnership.
A window that "sticks" doesn't necessarily mean shoddy work. The three main causes - incorrect glazing shims, building settlement, thermal expansion - are easily and quickly resolved by a qualified technician. Don't neglect the micro-adjustment during the first months - it's part of the natural "maturation" of a new window.
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