Define the use, footprint and finished level
- 1Finished level
- 2Sloping base
- 3Drainage away from the building
Measure the area, locate thresholds and obstacles, then draw the laying direction. Check local planning requirements before ordering materials.
Worked example: 5 × 4 m, giving 20 m². Measure the available build-up height between the base and the required finished surface.
Choose the construction system
Over natural ground, provide a stable, free-draining base. Over a sound concrete slab, pedestals, joists or paving may be suitable if the available height allows. Ask a competent professional to verify raised structures or work over unstable ground.
System suitability depends on loads, the supporting base and the limits stated by each manufacturer. A generic value cannot replace the product instructions.
Prepare and drain the base
- 1Boards
- 2Joists
- 3Pedestals
- 4Compacted aggregate
- 5Geotextile
- 6Ground
Remove topsoil where necessary, compact the base in layers and maintain a clear drainage route away from the building.
Calculate the excavation volumeTesCalculs→Size the structure and surface
- 1Joists
- 2Pedestals
- 3Centre-to-centre grid
Set support centres from the technical data for the actual board, paving unit, joist and pedestal you will use. Complete the full layout before ordering.
Calculate boards and joistsTesCalculs→Install, check and finish
Check alignment, level, perimeter gaps, ventilation and drainage throughout the installation. Keep all movement gaps clear.
Measure both diagonals of a rectangular layout. Equal diagonals confirm that it is square.