ᐅ Plastic windows cracking due to sunlight and thermal expansion

Hello,

I have the following problem with a newly built house (Dec. 2015) featuring the triple-glazed plastic windows listed below. Whenever the sun comes out (whether in winter at 6°C (43°F) outside temperature or in summer at 30°C (86°F)) the windows or window frames start making cracking noises. Strangely, only the windows on the south side (sunrise side) are affected.

The cracking noise can be heard quite loudly at intervals of about 30 seconds to one minute during the worst phases (sometimes the cracking is audible for several hours daily – usually until the sun reaches its highest point above the house at midday). It sounds like small popping noises. At times, the noise is so loud and frequent that sleeping during summer from around 7:00 a.m. is no longer possible.

So it definitely has to do with heat and expansion.

The issue was reported to the home builder in May 2016, who then passed the problem on to the subcontractor. So far, only the following measures have been taken:

1. Slightly enlarged (ventilation) drill holes in the frame

2. Shortened seals

3. Screws tightened and loosened

4. Screws completely removed

All attempts so far have been unsuccessful. I have found only a few forum posts on this issue, and unfortunately, no homeowner has ultimately reported a solution. I have read about some approaches.

Since this has been ongoing for almost two years and the building companies are now more or less refusing to try further measures, I am forced to involve a lawyer.

Manufacturer details:
Plastic windows:
Central seal S 9000 | IKD up to Uw W/m²K 0.72* (6016/6003/84)
Color scheme with Acrylcolor (base body and color permanently fused) inside white and outside RAL 7016 (anthracite)

The triple-glazed windows are fitted with insulating glass containing a "SWISSPACER". Ug from 0.5 W/m²K depending on profile thickness, g-value 53%.

Structure and properties:
1) High-tech coating for better light and heat transmission
2) Gas filling in the space between panes
3) Ideal glass spacing of 15 or 16 mm (0.6 or 0.63 inches)
4) Excellent optical properties

Attached is an image showing the window construction.

Do you have any further suggestions for solutions? In particular, I’m interested in how others affected have dealt with this and what the current status is. What are the chances of success when involving a lawyer or expert? I understand that windows can make some noise and that this is not automatically a defect. However, constant and loud cracking due to sunlight is, to me, not acceptable.

Thank you very much for any information, help, or feedback!