When selecting a waterproof decking system(s) for New Build and Refurbishment of car parks, a suitably qualified and experienced Architect/Engineer should always consider the following factors in order to select the most appropriate system to meet their requirement based on the construction of the structure, i.e in-situ concrete, steel framed, composite decks or precast units.


Ground movement or movement of the structure orof individual components, e.g. at construction joints, expansion joints is usually visible. Parking structures in use are always subject to dynamic loading

Atmospheric Carbonation

Atmospheric carbon dioxide gradually and progressively reduces the protective alkaline layer around the reinforcement, which will allow the steel to corrode.

Thermal Variations

  • Sunlight causes thermal expansion and stress cracking
  • Frost causes thermal contraction and freeze/thaw damage
  • Ultraviolet light causes degradation of organic materials, ie waterproofing membranes, resin and coatings

De-Icing Salts

De-icing salts are based on chlorides. The penetration of water contaminated by de-icing salt into concrete cause corrosion of embedded steel reinforcement and often cracking, spalling and delamination of concrete cover.


  • With water filling the pores and capillaries, concrete becomes susceptible to freeze/thaw damage
  • In carbonated concrete water ingress will allow steel reinforcement to corrode

Mechanical Exposure

The decks of parking structures are exposed to different levels of mechanical stress, according to their location and function, ie:-

  • Pedestrian levels: walkways
  • Standard levels: in primary parking bays
  • Heavy levels: entrance and exit areas, ramps and turning cycles

Aggressive Pollutants

  • Acidic oxide gases of sulphur and nitrogen from exhausts diffuse into the condensation and attack and corrode the concrete surface, which reduces the strength and increases the porosity
  • Some liquids, such as hydraulic brake fluid, are very aggressive and will attack concrete and steel surfaces

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