Z40770_Response to InformationRequest_NC_final

6     FOOTING AND SLAB SPECIFICATIONS

Footing Details

All footings must be founded a minimum of 300mm into the NATURAL STIFF SILTY CLAY (shown shaded on the
attached log sections). Dimensions and reinforcement requirements are detailed on the structural plans and
details.

Where the NATURAL STIFF SILTY CLAY is deep or is covered by the introduction of or the presence of existing fill,
the footings are to be increased in depth to reach this level. Alternatively the footings can be supported on
piers founded into the foundation material or deeper as required to obtain the required strength. Refer to the
structural plans for details.

Drilled Piers Supporting the Footings

Where the NATURAL STIFF SILTY CLAY is deep or to be covered by fill the footings can be supported on drilled
concrete filled piers founded at a minimum of 300mm into the NATURAL STIFF SILTY CLAY. The size and spacing
of these piers is nominated on the structural plans.

Floor Slab Details

The thickness and reinforcement for slabs on ground are shown on the structural plans.

Ground slabs may require thickenings or stiffening beams incorporated in their construction. It may be
advantageous to excavate them at the same time as the perimeter footings. Refer to the structural plans for
the locations and extent of these.

Where the stiffening beams intersect a perimeter footing, their base must be graded down to the footing base
level, 3 x N12 bars must be cogged into the footing and lapped 500 with the beams trench mesh. Refer to the
structural plans for details.

Where the stiffening beams intersect a blockbase or retaining wall, 3-N12 bars must be dowelled 150mm into
the blockbase and lapped 500 with the beams trench mesh. Refer to the structural plans for details.

A levelling layer under the ground floor slab is to comprise of granular material such as clean sand or crusher
dust compacted in 150mm layers. Either well graded sand or crusher dust can be used.

An approved polyethylene damp proof membrane of 0.2mm (min) thickness is to be placed over the levelling
layer. Laps are to be a minimum of 200mm and be taped. All service penetrations and punctures are to be
fully taped. The membrane is to be extended down the inside face of the perimeter footings and must continue
under any thickenings or stiffening beams.

Drilled Piers Supporting the Slab

Slab piers are required where there is more than 300mm of uncontrolled fill beneath the slab. They are to be
founded at a minimum of 300mm into the NATURAL STIFF SILTY CLAY. Special attention must be paid to the
extra slab thickening required over slab piers as detailed in the structural plans.

Drilled Pier Reinforcement

                               Pier Depth mm     Perimeter Piers       Slab Piers

                                up to 1500       None required       none required
                                1500-2500         2xN12bars          none required
                                2500-4000         4xN12bars           2xN12bars
                                4000-6000         6xN12 bars          4xN12bars

Unexcavatable Rock

Where unexcavatable rock is encountered at depths shallower than the founding depth the engineer is to be
contacted for alternative footing details.




    SCG Consulting Engineers                             3                                   SCG Ref: 26232(S)