Multifunctional coating films that can be applied in liquid form are provided for compressing, sealing, covering and preserving surfaces. The films include a composition of polysaccharide materials and/or homo- or heteroglycan water-soluble polysaccharide derivatives, polyol spacers, and crosslinkers with carbonyl or carboxylic function(s). As-applied, the composition is water-soluble and reactive, but after hardening it is capable of absorbing water or swelling, impermeable to water vapour, stable against water and UV and can be biologically degraded in a controlled manner. By reacting polysaccharide materials, polysaccharide derivatives and polyol spacers with cross linkers having carbonyl or carboxylic function(s), mechanically stable flexible films are obtained, which retain their mechanical properties up to a foreign material content of 80%. The films can swell in a controlled manner and can bind up to 75% water relative to their dry weight, corresponding to the degree of crosslinking and the spacer that is used.