October 30, 2017by admin

HOUSE AND BUILDING SETTLEMENT

MOST OF BUILDING SETTLEMENT IS DUE TO ONE OR MORE OF THESE NON-COMPLIANCE ISSUES

Trees

According to Clause B2.3 of AS2870 – Australian Standard Residential Slabs and Footings, planting of trees should be avoided near the foundation of a building or neighbouring building on reactive sites as they can cause damage due to drying of the clay at substantial distances.

AS2870 recommended that trees should not be located closer to foundations than a distance equivalent to between 0.75 and 1.5 times their mature height (depending on soil reactivity and tree grouping).

Surface drainage

Section 3.1.2.3 of the BCA states:

‘Surface water must be diverted away from Class 1 buildings as follows:

(a)         Slab-on-ground — finished ground level adjacent to buildings:

the external finished surface surrounding the slab must be drained to move surface water away from the building and graded to give a slope of not less than (see Figure 3.1.2.2);

  • 25 mm over the first 1 m from the building in low rainfall intensity areas for

            surfaces that are reasonably impermeable (such as concrete or clay paving); or

  • 50 mm over the first 1 m from the building in any other case.

(b)        Slab-on-ground — finished slab heights:

the height of the slab-on-ground above external finished surfaces must be not less than (see Figure 3.1.2.2);

  • 100 mm above the finished ground level in low rainfall intensity areas or

 sandy, well-drained areas; or

  • 50 mm above impermeable (paved or concreted areas) that slope away from 

the building in accordance with (a); or

  • 150 mm in any other case.

Eaves gutters and downpipes

Part 2.2 of the BCA section F2.2.1 Surface water states:

A building including any associated site work is to be constructed in a way that protects people and other property from the adverse effects of redirected surface water.

Part 2.2.1 of the BCA states:

‘(a)           Surface water, resulting from a storm having an average recurrence interval of 20 years and which is collected or concentrated by a building or site work, must be disposed of in a way that avoids the likelihood of damage or nuisance to any other property.

(b)           Surface water, resulting from a storm having an average recurrence interval of 100 years must not enter the building.

(c)            A drainage system for the disposal of surface water resulting from a storm having an average recurrence interval of –

(i)          20 years must –

(a) convey surface water to an appropriate outfall; and

(b)      avoid surface water damaging the building; and

(ii)         100 years must avoid the entry of surface water into a building’

 

Comment