1. Poor adhesion at high temperatures or sun exposure causing rapid thickening of the glue and reduction of its adhesive capacity.
2. Poor substrate quality, without the use of the appropriate materials in cement mortar application, creating pores and cracks
3. Poor or inadequate quality of the glue.
The situation is worsened because the water is drained when the pool is not being used, leading to moisture entrapment (due to the three reasons mentioned above) and ice formation within the substrate, causing detachment due to thermal expansion.
This phenomenon is more severe in areas that experience frosting.
Unfortunately, once things go bad, it’s easy for the situation to get out of hand and become irreversible, no matter how many times you try to patch it up; this is why the problem surfaces at a different spot every year.