Z40770_Response to InformationRequest_NC_final

D.2     Recommendations for Owners
Foundation Maintenance and Owners Responsibilities: The soils surrounding and under the foundations must be protected from scour
or washout from stormwater by ensuring adequate drainage as noted above.
Localised concentrations of moisture such as overflows from hot water cylinders or air conditioners can lead to excessive localised
foundation movements and must also be adequately drained away from the foundations as noted above.
In all types of soil conditions, if an automatic watering system irrigates within 2.5 meters of a foundations, instability problems and excessive
foundation movements are likely to occur. Also site drainage as discussed above must be maintained.
Ongoing foundation maintenance is documented in the CSIRO handout BTF-18, attached to the client’s copy of this report. (Additional
copies available upon request.)
Refer to the attached detail sheet “General Requirements for Site Drainage”
Additional Requirements - Class A & S Sites: Trees and dense shrubs must be kept well away from the building foundations. Refer to
the following section “Recommendations – Builders/Owners – Trees”. In all types of soil conditions, if an automatic watering system irrigates
within 2.5 meters of a footing, instability problems may occur. Water should not be allowed to pond on the ground near the building.
Finished surface grades around the building should also ensure scour of soils cannot occur. Additional field gullies and drainage might be
required. In all instances the ground should be sloped away from the foundations at a grade of no less than 1 in 20 (vertical to horizontal)
for at least 1.5m.
Additional Requirements - Class M, H & E Sites: Trees and dense shrubs must be kept well away from the building foundations. Refer
to the following section “Recommendations – Builders/Owners – Trees”.
The soil near the building should be protected against the increased moisture that occurs in gardens or permeable landscaping built
adjacent the foundations. Automatic irrigation systems must not be used adjacent structural foundations. If required, these forms of
landscaping must be constructed over impermeable membranes that drain the excessive moisture away from the foundations into correctly
installed field gullies and drains.
We strongly recommend the construction of hard landscaped paths or terrace slabs adjacent building foundations for at least a distance of
1.5m to protect the foundations from excessive moisture.

D.3     Recommendations – Builders/Owners - Trees
Trees and landscaped gardens can have a dramatic influence over the moisture content of the soils they are grown in. This can lead to
increased soil movement through shrinking and swelling. Where these trees or gardens are within close proximity of structural foundations
the soil movements can affect the structural integrity of the foundations.
For Class M, H and E sites the following recommendations for the minimum distance between trees and footings should be followed:-

                                          Site Class                     Offset to Tree
                                           Class M            :             0.75 x h
                                           Class H            :             1.0 x h
                                           Class E            :             1.5 x h
Where ‘h’ is the mature height of the tree, further refinement of this recommendation can be pursued where tree species can be considered.
Where a row or group of trees exists the above recommendation should be doubled.
In some instances the installation of root barriers can lessen the effect of trees on foundation performance. Please contact SCG Consulting
Engineers for options.
The following table provides some guidance on mature tree heights:-
        APPROXIMATE TREE HEIGHTS
10 to 20m Height – Acacias, Ash, Athel Tree, Candlebark, Manna Gum, Pepper Tree, Willows, Yate, Yellow Gum
20 to 30m Height – But-But, Cedars, English Oak, Lemon Gum, Palms, Planes, Sheoaks, Silky Oak, Spotted Gum, Casuarina
30 to 60m Height – Blue Gum, Cypress, English Elm, Figs, Karri, Pines, River Gum, Sugar Gum


The removal of trees from the proposed construction can also greatly affect the moisture conditions of the soil. We recommend allowing the
soil time to reach moisture equilibrium prior to construction commencing. Please contact our office for further guidance on this matter.




SCG Consulting Engineers                                     Appendix Page 5 of 7                                              Appendices.1