Part 4.2 Footings, slabs and associated elements
SA 4.2.8 Damp-proofing membrane2019: SA 188.8.131.52
A continuous damp-proofing membrane must be installed under slab-on-ground construction for all Class 1 buildings and for Class 10 buildings where the slab is continuous with the slab of a Class 1 building as follows—
- Materials: A damp-proofing membrane must be—
- 0.2 mm nominal thickness polyethylene film; and
- high impact resistant with resistance to puncturing and moisture penetration, determined in accordance with criteria specified in clause 184.108.40.206 of AS 2870; and
- branded continuously “AS 2870 Concrete underlay, 0.2 mm High impact resistance” together with the manufacturer’s or distributor’s name, trade mark or code.
- Installation: A damp-proofing membrane must be installed as follows—
- lap not less than 200 mm at all joints; and
- tape or seal with a close fitting sleeve around all service penetrations; and
- fully seal where punctured (unless for service penetrations) with additional polyethylene film and tape.
- The damp-proofing membrane must be placed beneath the slab so that the bottom surface of the slab is entirely underlaid and extends under edge beams to finish at ground level in accordance with Figure 4.2.8.
SA 4.2.10 Concrete2019: SA 220.127.116.11(d) to (g)
Concrete must comply with the following:
- Concrete must be manufactured to comply with AS 3600; and—
- have a strength at 28 days of not less than 20 MPa (denoted as N20 grade); and
- have a 20 mm maximum nominal aggregate size; and
- have a nominal 100 mm slump.
- Water must not be added to the mix to increase the slump to a value in excess of that specified.
- Concrete must be placed, compacted and cured in accordance with good building practice.
- Concrete in slabs must be adequately compacted, and slab surfaces, including edges, moist cured for 7 days.
- After vertical surfaces are stripped of formwork, slab edges must be finished prior to curing.
- Loading of concrete slabs with stacked materials or building plant must not occur for a minimum of 7 days after pouring although construction of wall frames and setting out brickwork may be undertaken during this period.
- Concrete must not be poured if the air temperature on site exceeds 32ºC unless written instructions from a Professional Engineer are followed.
- Complete discharge of the concrete from the truck should be made within one and a half hours of initial mixing with water unless a suitable retarder has been specified.
- Compacting concrete by vibration removes air pockets and works the concrete thoroughly around reinforcement, service penetrations etc. and into corners of formwork to increase durability and resistance to termite infestation and salt damp attack. Care should be taken not to over-vibrate. The finishing and curing of slab edges provides an improved edge finish which is resistant to edge dampness.
- Care should be taken when using chemical curing methods, because some products may not be compatible with adhesives used to fix surface finishes to the slab.