Because there is 8 cm thick insulation layer inside the window opening, the expansion screw for installing the window must be lengthened, and the length of the expansion screw of 10 cm is obviously insufficient. Because according to the thickness of this insulation layer, the part that goes deep into the wall connection is only two centimeters, and the installation of the window must go deep into the wall about five centimeters.
For those who have installed 10 cm long expansion screws, there is indeed a hidden danger of unstable installation, but as long as the floor is not very high, such as below six floors, the possibility of the window falling off is very small.
Then, if it has not been glued, it is recommended to brush cement mortar on the side of the window frame, and the cement mortar should cover the window frame by about 3 mm, so that there will be no worries about the unstable installation of the window frame.