Multi-storey car parks

At a glance

There are over 4,500 multi-storey car parks in the UK, many dating back to the 1960s, when design standards were less onerous than today. So, there is a legacy of poorly-constructed and equally poorly-maintained structures that demand expensive and extensive remedial work. Often car parks are treated with little respect for the serious potential problems that may exist. See the Introduction.

The engineering professions regard multi-storey car parks with the same level of caution as they do bridge structures; both are exposed elements subjected not only to the weather but to aggressive forms of deterioration from chlorides in road salts and other chemicals. See Modes of deterioration.

While steel-framed car parks are not unusual, most are of either precast or reinforced concrete. All structures are vulnerable to decay arising from water brought in on vehicles or from the weather. Intermediate floors and access ramps are often worse affected than top floors as a degree of regular washing under rainfall can help to reduce the build up of harmful chemicals. On intermediate floors chemicals become more concentrated as there is less dilution by rain. See Urea and chlorides.

Deflection of structures leads to ponding and difficulties with rainwater disposal. Water then works its way into the structure via poorly-designed or maintained movement joints (or cracks arising through lack of movement joints) where it may assist in the corrosion of reinforcement. Often, leaks occur in the areas that are structurally most vulnerable, such as around balustrade fixings, half joints, etc. See Problems with movement.

The Standing Committee on Structural Safety recommends that owners of car parks should:

  • commission inspections by suitably experienced engineers before commissioning repairs (these inspections should go beyond those areas that are visibly defective);
  • identify the risk of progressive collapse; and
  • establish the suitability of edge barriers to resist accidental vehicle loads and to protect small children from falling.