01.1 - Geotechnical Report · OPW18/0008

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6.0 RECOMMENDATIONS

Due to the shape and size of the proposed house we recommend that footings are designed based on an appropriate
waffle raft slab deepened with steel screw piers founded in dense natural sands. Alternatively, foundations could be
designed as a conventional stiffened raft slab subject to further geotechnical investigation to confirm the adequacy
and consistency of the existing sand fill.

After the final building platform is created, ensure that positive drainage exists away from the house area. Use a
minimum surface gradient of 1 in 10, or 50mm, away from the footing beams for at least one (1) metre.

Existing or proposed trees shall be kept a minimum distance equal to their mature height away from the footings.
Where rows or groups of trees are involved, the distance from the building should be increased. Root barriers are to
be installed if these trees are likely to affect foundation performance.

Contact this office for full foundation details once house plans are completed.
7.0 QBCC COMPLIANCE

This building site foundation investigation and classification has been undertaken in accordance with AS 2870
“Residential slabs and footings”. The Queensland Building and Construction Commission’s Rectification of Building
Work policy has a requirement for the following information to be supplied to us by the builder, and that we consider
this information in determining the site classification. (Information available at time of classification is indicated by KX]
below)

EX] Information to correctly identify and locate the site;
&X] Contours of the site;

KX Location of existing trees;

LI Overland flow paths;

(J Building footprint and platform level;

( Relevant land search information.

8.0 DRAINAGE
At no time during construction, or after, is water to be permitted to pond in or near footings. Ensure all fill batters away
from the final house, making sure all surface runoff is directed away from the house. (Maximum batters are to be -

1:1.5 for clay soils, and 1:1.7 for sand soils.)

All roof drainage to be discharged either to the street, or into the Local Authority's stormwater system or in accordance
with the Local Authority's requirements.

All external patio, carport and verandah slabs to be graded at not less than 1 in 100 to remove all surface water away
from the house area.

9.0 OWNER’S RESPONSIBILITIES

Stable moisture conditions near the footings, is the responsibility of the owner/occupier of the dwelling. Large changes
in moisture conditions around the structure’s footings, will cause movement, and may lead to damage of the house.
This report must be read in conjunction with the attached report, "Guide to Home Owners on Foundation Maintenance
and Footing Performance", sheet No. 10-91, produced by Dr P.F. Walsh of the CSIRO.

10.0 REPORT LIMITATIONS

Recommendations given in this report are based on the findings of the soil investigation attached. Any change to the
building location may require further investigation and analysis.

Every reasonable effort has been made to locate test sites so that the bores are representative of the soil conditions
within the area of construction. The client should be made aware that exploration is limited by time available and by

 

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