A common problem with casement frames is that often the opening sashes of windows “rub” (catch) during their operation (opening – closing) or when they tilt. There are two main reasons why windows rub:
A. The installation of closed sashes (with the use, by the aluminum frame manufacturer, of closed opening glass sashes, it is not possible to shim the glazing units).
B. Incorrect shimming of the glazing units or their complete absence.
C. Incorrect manufacturing measurements and ‘play’ in the frames.
We will examine the second reason why windows rub. First, let’s see what shims are and what they are used for. Shims are plastic spacers inserted between the glazing unit (glass) and the aluminum profile. Their purpose is:
- The correct distribution of the weight of the glazing unit (glass)
- To maintain the correct position of the sash relative to the frame casing
- To protect the glazing unit from breakage
- To transfer the weight of the glazing unit to the hinge side
- In sliding frames, to prevent the movement of the glazing unit within the aluminum profile when it is being slid.
With all the above, we understand that the use and shimming of glazing units are imperative for the proper long-term operation of frames (casement – sliding).
Why do sliding aluminum balcony doors not lock
The reasons why sliding balcony doors may not lock are usually the following:
- They have not been shimmed
- The glass sashes have tilted (‘settled’)
- The lock strikes have shifted
- The locks have been damaged
- The bottom guides have been damaged
- In dark-colored thermal break sliding frames, the bowing phenomenon
But what is the bowing phenomenon?
Thermal break frames (glass sashes) are divided into two sections, the inner section and the outer section, with insulating material (e.g., polyamides) inserted in the middle, which provides thermal insulation. When we have dark-colored thermal break frames that are directly exposed to intense heat and sunlight, they expand from the outside due to the heat. However, inside the house, a different temperature prevails (air conditioning, etc.), causing the aluminum to contract. This creates difficulty in locking the glass (due to linear expansion only of the outer side of the hybrid sash) and often they rub – catch. This only happens during the hours when the sun hits the aluminum on very hot days and in dark-colored frames. The phenomenon does not appear when there is sufficient shading or when the frames are painted in light shades. The cast handle – sashes with a bar prevent this phenomenon as they do not allow linear expansion.
For more details, click on frame installation
