Revisions log for Answer #1561
This is the answer to the question Why do windows make a crackling noise in the evening?
Revision 1
The nature of the deformations is as follows:
1. PVC has a high coefficient of linear thermal expansion.
2. It also has a low thermal conductivity.
3. Therefore, the front walls of the house and street are heated / cooled differently, respectively, and expand differently. Therefore, when heating/cooling from the street side, the profile tends to bend towards the warmer wall: in winter towards the room, in summer towards the street. The greater the temperature difference, the greater the deflection. Actually, the so-called "fasteners": anchors, self-tapping screws, dowels, plates – serve to prevent these deformations perpendicular to the plane of the window. If there is not enough fasteners, then the deformation even with a dead reinforcement can be quite tangible. If there are enough fasteners, the deformation energy is redirected to the plane of the window by torsion. Then the determining factor may be the lack of support pads, poor quality of the foam joint.
Clicking can be many things: threaded fasteners on the reinforcement, anchor plates, poorly secured sills and window sills, the connection imposts.