Technical
Details
The following drawings are to be read in conjunction with Table 1 and Table 2.
For VoidForm® height – H, Reinforcing fabric – F and size of Y bar bottom reinforcement for each
VoidForm® waffle raft slab type, refer to Table 1.
Table 1
Additional reinforcement for external RIBS where stem width exceeds 150mm.
| Stem Width Max |
Additional Top Steel |
Additional Bottom Steel |
| 200mm | 1-Y12 | 2-Y12 |
| 330mm | 2-Y12 | 3-Y12 |
| 440mm | 3-Y12 | 4-Y12 |
Table 2
VoidForm® Waffle Raft Slab Proportions
| Type | VoidForm® Height |
RIB Construction reinforcing fabric - F. Main R'ment – Y |
| 1 | 225mm | RIB depth - 310mm O/A 1-Y12 Bot. F72 in top |
| 2 | 300mm | RIB depth - 385mm O/A 1-Y12 Bot. F82/72 in top |
| 3 | 300mm | RIB depth - 385mm O/A 1-Y16 Bot. F82 in top |
NOTE: The next VoidForm® must be set down "L" is 600mm for Y16 bars and 450mm for Y12 bars.
O/A denotes overall height.
Surface fill, roots and vegetation are to be removed from the building platform. Site is to be cut and/or filled to form a level bench to within approx 50mm. Up to 300mm of approved compacted fill may be used (refer AS 2870-1996). If additional fill is required or where a site has existing fill, contact an engineer prior to further construction or design. Pressure required is 40KPa.
Place suitable quarry products (well-graded quarry sands or rubble having a particle size of 4mm maximum) up to 50mm in depth to obtain a level platform within +/- 5mm. If the building platform is level after the above-mentioned site works, quarry material may not be required and only used in low areas. It is recommended that this material extends 1.0m past the building line.
A minimum RIB width of 110mm must be maintained where plumbing risers clash with RIBs. This may be achieved by cutting VoidForm® to suit and lapping reinforcement. Concrete strength to be F'c=20MPa and concrete is to be mechanically vibrated. Pour RIBs as part of slab.
This detail sheet shall be read in conjunction with the footing plan, architectural drawings, soil report and
AS 2870-1996.
NOTE: Details are to be used as a guide only. Footing designs are to be designed by a suitably qualified engineer. Reproduced with permission of Buratt Engineering Pty. Ltd.
Performance Comparisons
Type of Construction
| Site Class | VoidForm® Waffle Raft Slab Site | Stiffened Raft Slab Sitesˆ | ||||||
| Depth of VoidForm® |
Beam Depth (mm) |
Bar Size Beam Reinforcement |
Slab Fabric | Depth (D) (mm) | Bottom Reinforcement | Spacing Centre to Centre (M) |
Slab Fabric | |
| Class A | ||||||||
| Clad frame, articulated masonry veneer and masonry veneer | 175mm | 260 | Y12 | F72 | 300 | 3-8TM | – | F72 |
| Articulated full masonry and full masonry | • | • | • | • | 400 | 3-8TM | – | F82 |
| Class S | ||||||||
| Clad frame | 175mm | 260 | Y12 | F72 | 300 | 3-8TM | – | F72 |
| Articulated masonry veneer |
175mm | 260 | Y12 | F72 | 400 | 3-8TM | – | F72 |
| Masonry veneer | * | * | * | * | 300 | 3-11TM | – | F82 |
| Articulated full masonry | • | • | • | • | 400 | 3-11TM | – | F82 |
| Full masonry | • | • | • | • | 450 | 3-11TM | 5.0* | F82 |
| Class M | ||||||||
| Clad frame | 225mm | 310 | Y12 | F72 | 300 | 3-11TM | 6.0* | F72 |
| Articulated masonry veneer | 225mm | 310 | Y12 | F72 | 400 | 3-11TM | 6.0* | F72 |
| Masonry veneer | 225mm | 310 | Y12 | F72 | 400 | 3-11TM | 5.0* | F72 |
| Articulated full masonry | • | • | • | • | 500 | 3-11TM | 4.0 | F82 |
| Full masonry | • | • | • | • | 800 | 3-Y16 | 4.0 | F92 |
| Class M-D | ||||||||
| Clad frame | 225mm | 310 | Y12 | F72 | 400 | 3-11TM | 5.0* | F72 |
| Articulated masonry veneer | 225mm | 310 | Y12 | F72 | 400 | 3-11TM | 4.0 | F72 |
| Masonry veneer | • | • | • | • | 500 | 3-12 | 4.0 | F82 |
| Articulated full masonry | • | • | • | • | 625 | 3-12TM | 4.0 | F92 |
| Full masonry | • | • | • | • | – | – | – | – |
| Class H | ||||||||
| Clad frame | 225mm | 310 | Y12 | F72 | 400 | 3-11TM | 5.0* | F72 |
| Articulated masonry veneer | 300mm | 385 | Y12 | F82 | 500 | 3-12TM | 4.0 | F82 |
| Masonry veneer | • | • | • | • | 700 | 3-Y16 | 4.0 | F92 |
| Articulated full masonry | • | • | • | • | 1000 | 4-Y16 | 4.0 | F102 |
| Full masonry | • | • | • | • | – | – | – | – |
| Class H-D | ||||||||
| Clad frame | 300mm | 385 | Y16 | F72 | 500 | 3-11TM | 4.0 | F82 |
| Articulated masonry veneer | 300mm | 385 | Y16 | F82 | 600 | 3-12TM | 4.0 | F92 |
| Masonry veneer | • | • | • | • | – | – | – | – |
| Articulated full masonry* | • | • | • | • | 1200 | 4-Y16 | 4.0 | F102 |
| Full masonry | • | • | • | • | – | – | – | – |
ˆ For further information refer to AS 2870 – 1996 page 21, note 1.
* For further information refer to AS 2870 – 1996 page 21, note 8.
• Engineered option to site requirement.
| Depth of VoidForm® | VoidForm® Waffle Raft Proportions | GUIDE ONLY: details to be verified by an Engineer |
| 225mm | Type 1 – Rib depth is 310mm overall with 1/Y12 bottom and F72 top | |
| 300mm | Type 2 – Rib depth is 385mm overall with 1/Y12 bottom and F72 top | |
| 300mm | Type 3 – Rib depth is 385mm overall with 1/Y16 bottom and F82 top | |
| 375mm | Type 4 – Rib depth is 460mm overall with 1/Y12 bottom and F82 top | |
| Type 5 – Rib depth is 610mm overall with 1/Y16 bottom and F82 top | ||
| (in addition 1/Y16 is required in the perimeter [N1] rib) |
Note: All types have slab thickness of 85mm. All rib depths measured from top of slab (all ribs 110mm wide).