Introduction
As urbanisation expands and the number of cars on our streets continues to grow, the lack of parking places is forcing us to reconsider our use of space, to maximise its potential, and to investigate the possibility of vertical development. Modern offices, apartment blocks and shopping centres use a combination of hard and soft landscaping on their flat roofs and underground parking facilities to make the most of their limited open space. Careful planning and good design will improve overall living conditions within our cities by creating large, open green areas and places for recreation and leisure, while sub-surface structures provide the necessary underground parking that will prevent it from intruding into the urban environment.
Careful planning by architects and design engineers can maximise the use of valuable open spaces by covering roofs with extensive and/or intensive planting schemes that are combined with suitable hard-landscaping to provide access for vehicles and/or pedestrians. Any design will need to accommodate specific construction requirements such as the required composition depth for elemental paving, the depth of growing medium required by the planting scheme, the maximum permissible surface loads, the provision of a suitable waterproofing system, and so on.
When paving of any type is used, it will not be constructed over a prepared sub-grade, as would normally be the case, but will be constructed on top of a structural deck, and so the design must address the following considerations:
- the difference in behaviour and reaction that can be expected between natural sub-grades and constructed roof decks
- the waterproofing system must be suitable for both static and the dynamic loadings
- the type of roof construction, whether it is a ‘warm roof‘, an inverted roof, or a roof construction without thermal insulation
- the compressive strength of any thermal insulation
- the type and depth of any granular materials, such as sub-base layers or laying courses
- the type, depth and behaviour of any elemental paving
- the anticipated usage and the predicted intensity of use of the roof deck structure by both people and vehicles, and the loads imposed as a consequence of such use.
To be continued.
Design considerations
Standards
Load classification
Roof constructions
Thermal insulation
Waterproofing systems
Details
Design of falls – structural roof deck
Roof drainage
The build-up of a podium and parking roof deck
Separation layer
Slip layer
Protection layer
Drainage layer
Filter layer
Drainage Systems
Sub-base layer
Sub-base layer
Levelling layer
Laying course
Paving
Podium and/or parking roof decks combined with intensive green roofs
Podium deck and Parking Deck Systems
Podium Deck System – load class 1
Warm roof construction/roof construction
a. Build-up without sub-base layer
b. Build-up including sub-base layer
c. Build-up including levelling layer
d. Build-up including grass tiles
Inverted roof construction
a. Build-up without sub-base layer
b. Build-up including levelling layer
Park Deck System – cars – load class 2
Warm roof construction/roof construction
a. Build-up without sub-base layer
b. Build-up using larger concrete flags/slabs without sub-base layer
c. Build-up including sub-base layer
d. Build-up including grass tiles
Inverted roof construction
a. Build-up without sub-base layer
b. Build-up using larger concrete flags/slabs without sub-base layer
c. Build-up including sub-base layer
Park Deck System – heavy goods vehicles – load class 3
Warm roof construction/ roof construction
a. Build-up using large format concrete flags/slabs without sub-base layer
b. Build-up including sub-base layer
c. Build-up including grass tiles
Inverted roof construction
a. Build-up using larger concrete flags/slabs without sub-base layer
b. Build-up including sub-base layer
Composition of an parking deck – load class 2 combined with intensive planting scheme