‘Semi-basement’ parking is structured parking built partly below ground level, either as a partial basement to a building or covered with structure above.
By their nature, semi-basements require less excavation, substructure and waterproofing in comparison to full underground parking. Semi-basement parking can help solve certain site-specific issues. For example, semi-basements are suitable for sites with a water table that prevents construction of deeper basements.
Semi-basements invariably result in the ground floor being raised above street level. This is an advantage for residential buildings, as the raised level helps to avoid privacy issues to ground floor areas whilst offering greater outlook to the street. Care needs to be taken if retail or commercial space is provided at this raised ground level as it is then harder to provide level access for wheelchair or pushchair users.
Where a semi-basement structure sits above ground level ventilation grilles should be incorporated into the facade and/or landscape design to reduce the visual impact of the car park structure.
Semi-basement car parking should be considered wherever possible, but is especially suited to sites with medium to high density and land value.
Locate vehicle entrance ramps to an semi-basement parking so that disruption to traffic, cyclists and pedestrians is kept to a minimum i.e. via a side street rather than a main road.