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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).