The problem: Many screeds are unsuitable for old buildings

Illustration 1.: Emergence of house fungus due to impeded diffusion in the floor construction. Source: FUSSBODEN ATLAS® (Floor Manual)
Illustration 1.: Emergence of house fungus due to impeded diffusion in the floor construction. Source: FUSSBODEN ATLAS® (Floor Manual)
Illustration 2: Crack emergence due to intensive screed contraction. Source: FUSSBODEN ATLAS® (Floor Manual)
Illustration 2: Crack emergence due to intensive screed contraction. Source: FUSSBODEN ATLAS® (Floor Manual)

Standard screeds used in old buildings

arrowcan impede diffusion immensely causing the emergence of      fungi and mould,
arroware often very thick and extremely heavy,
arroware often inconvenient for the screed-layer due to their thickness,
arrowfrequently cannot be compacted completely,
arroware often unsuitable for floor heating and cooling systems,
arrowrequire higher flow temperatures in the floor heating system
     and heat up slowly,
arrowoften use up a lot of energy,
arrowleave little room for supplementary insulation,
arrowcan offer low protection against footfall sound and vibrations,
arroware sometimes not fire resistant,
arrowcan contain a lot of water which is prone to spread around the
     site later on,
arrowoften contract intensely and dry slowly,
arroware usually not suitable for all kinds of laying procedures
     (base-bonded, laid on a separating layer, laid on insulation)
      and common floor coverings,
arroware often not water-resistant,
arrowcan enhance the emission load of a room,
arrowoften show little load-bearing capacity,
arrowcan often not be recycled, hence their disposal is expensive,
arroware primarily applicable to large undifferentiated surfaces.