Due to missing insulation capillary moisture builds up in the masonry. With moisture, soluble salts get into the masonry and are deposited in the capillaries, which reduces their diameter. This allows for water to rise higher. The water evaporates from the masonry surface, the salts are dried and crystallized. This increases their volume and disturbs the surface layers due to crystalline pressure.
This process is continually repeated and the damages are visible:
- due to humidity, the thermal insulation capacity of the masonry is reduced, damp plaster starts to crack due to frost and this opens way to dampness;
- in the interior, the damp masonry causes occurence of fungi and rotting bacteria, which reduces the comfort of used spaces;
- with the interaction of crystallizing salts, shedding of plaster and other damage of masonry occurs, while the damage of masonry can also be dangerous from the viewpoint of its capacity;
- crystallized salts can also have hygroscopic properties - they can bind water from the ambient air; along with acid rains they are a suitable environment for bacteria, fungi and algae - these try to preserve their damp environment and abosrb the moisture from the surrounding air;
- with impermeable lining the humidity rises higher than in case of masonry without lining.