6.0 Design Approach

There are 2 methods of construction – typical and tie-down. Typical is the most common method of building whilst the tie-down method is required for cyclonic or high wind areas (as determined by an engineer). This guide provides information for both building methods.

Important Note

It is the responsibility of the architectural designer and engineering parties to ensure that the information in the Hebel PowerBlocks Design and Installation Guide is appropriate for the intended application. The recommendations of this guide are formulated along the lines of good building practice, but are not intended to be an exhaustive statement of all relevant data. Hebel accepts no responsibility for or in connection with the quality of the recommendations or their suitability for any purpose when installed.

Scope

The Hebel PowerBlocks Design and Installation Guide has been created to provide information for detached residential buildings. The design information in this guide has been condensed from the Hebel Technical Manual and AS3700 Masonry structures. The design basis is AS3700 Masonry structures, Section 12 Simplified design of masonry for small buildings. The footing and slab design is based on AS2870 Residential slabs and footings – Construction.

Refer to Table 6.1 for Building Geometry Limitations.

Design Parameters

The structural design information in this guide is based on the data and assumptions in Table 6.2, 6.3 and 6.4.

Design Sequence

Fig. 6.1 details Hebel recommendations for how to design a Hebel PowerBlock home.

Fig 6.1:  Flow Chart

Table 6.1: Building Geometry Limitations

 2 storeys max
 Max. height to underside of eaves  6.0m
 Max. height to top of roof ridge  8.5m
 Max. building width incl. verandah but not eaves  16.0m
 Max. building length  5x width
 Max. lower storey wall height  3.0m
 Max. upper storey wall height  2.7m
 Max. floor load width on external wall  3.0m (6.0m single span floor)
 Max. roof load width on external wall  3.0m (6.0m rafter/truss span)
 Max. floor load width on external wall  6.0m

Where the building geometry is outside the above limitations, the designer must refer to the Hebel Technical Manual and AS3700 Sections 1-11.

Table 6.2: Design Parameters

Hebel PowerBlock material properties:  
 Nominal Dry Density  470 kg/m2
 Working Density (S.T.)  611 kg/m2
 Working Density (L.T.)  500 kg/m2
 Characteristic Compressive Strength, f’m  2.25 MPa
 Characteristic Flexural Tensile Strength, f’mt  2.20 MPa
 Characteristic Shear Strength, f’ms  2.30 MPa
 Characteristic Modulus of Elasticity, EST 1125MPa
 Characteristic Modulus of Elasticity, ELT 562 MPa

Table 6.3 Design Parameters – Permanent and Imposed Actions

Permanent Actions (Dead Loads):
Floor – Superimposed 1.00 kPa
Roof – Tile 0.90 kPa
Roof – Sheet 0.40 kPa
Framed Floor/Deck – Timber 0.50 kPa
Framed Deck – Tile 0.50 kPa
Pergola Roof – Tile 0.80 kPa
Pergola Roof – Sheet 0.32 kPa
Hebel PowerFloor System 0.80 kPa
Hebel Floor Panel System – 250mm 1.90 kPa
Hebel PowerBlock Wall – 250mm, 2700mm (H) 4.60 kN/m
Hebel PowerBlock Wall – 150mm, 2700mm (H) 2.76 kN/m
Imposed Actions (Live Loads):
In accordance with AS 1170. 1:2002
Floor – general 1.50 kPa
Deck 2.00 kPa

Table 6.4  Design Parameters – Wind Actions (General wall areas)

Wind Classification
(AS4055)
Wind Pressure (kPa)
Serviceability, Ws Ultimate, Wu
N1 0.41 0.69
N2 0.41 0.96
N3 0.61 1.50
N4 0.91 2.23
N5 1.33 3.29
N6 1.82 4.44
C1 0.61 2.03
C2 0.91 3.01
C3 1.33 4.44
C4 1.82 5.99

Image 6.1:  Hebel PowerBlock home

Image 6.2:  Hebel PowerBlock home

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8.0 System Components

Products

Hebel stocks many of the products and materials required to construct your Hebel home.

Product Description Product Description
  Hebel Thermoblocks

50mm – 300mm (25mm
increments)

  Hebel Adhesive
20 kg bag

Used for gluing the blocks together at vertical and horizontal joints

  Sill blocks

600x200x50mm thick or
100mm thick, 30º slope

  PowerFloor Panels

1800mm x 600mm x 75mm

  Hebel Mortar
20 kg bag

Used as thick bed mortar base
to provide a level base for the
first course

  Custom PowerFloor Panels

150mm – 250mm x 600mm
by up to 6m

  Hebel Lintels

To suit openings up to 5m

  Hebel HighBuild render 20kg bag

Used as a preparation coat
to level surface providing an
even true surface

  Stair treads

300mm x 175mm x 1m
or 1.2m

  Control joint tie

Used at every third
course in control joints

  Hebel Patch
10kg bag

Used to prepare minor chips
or damage to blocks

  Sliding joint tie

Fixed to RHS/SHS column
every second course

  Corrosion Protection Paint

To coat exposed
reinforcement during cutting

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10.0 Tools & Equipment for Construction

Hebel PowerBlocks can be laid using construction tools/equipment.

String Line – A string line is required to accurately set out and lay Hebel PowerBlock Walls.

Brick/Blocklaying Profiles – used to gauge the block course are being laid level.

Mixing Bucket – a minimum 20 litre bucket is required for mixing Hebel Mortar, Hebel Adhesive and Hebel HighBuild render.

Electric Drill – an electric drill is required to mix the Hebel Mortar, Hebel Adhesive and Hebel HighBuild render. It is also used to drill clearance holes in the blocks so they can be placed over the tied down rods where required.

Stirrer – fitted to the electric drill, the stirrer is used to mix the Hebel Mortar, Hebel Adhesive and Hebel HighBuild render inside the mixing bucket.

Notched Trowel – the notched trowel is used to apply the Hebel Adhesive to the Hebel surfaces. The width of the trowel must match the block thickness to ensure the adhesive is applied with full and even coverage.

Rubber Mallet – a rubber mallet is required to ‘tap’ the Hebel PowerBlocks onto the adhesive and into place.

Spirit Level – required to install the blocks level and plumb.

Hand Saw – a Hebel handsaw can be used to cut Hebel PowerBlocks to length and height.

Powered Bandsaw – a bandsaw is ideal for cutting Hebel PowerBlocks. (perfect when there are many site cuts to be performed).

Hebel Square – a purpose built square is available for use when marking and cutting Hebel PowerBlocks.

Steel, Plastic and Timber Trowels – these trowels may be required for the installation of the Highbuild render and texture coatings.

Sanding Float – used to even out inconsistencies in the Hebel PowerBlock Wall in preparation for render/texture coats.

Hebel Hand Router – may be used to chase services into solid Hebel walls.

Circular Saw – (fitted with a diamond blade) may be used to chase services into solid Hebel walls.

Electric Router – may be used to chase services into solid Hebel walls.

Crane – may be required to lift large Hebel Lintels and Hebel custom floor panels.

Lifting Grabs – required for use in conjunction with crane for lifting Hebel lintels and custom floor panels.

Scaffold – Scaffold is required when building block walls. The amount of scaffold depends on the height of the walls.

Sealant Gun – required to fill the control joints in the Hebel PowerBlock Walls.

Image 10.1:  Hebel® tools

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15.0 Construction Details – Tie-down PowerBlock

Required only if specified by design /project engineer

Fig 15.1:  Strip Footing, Double Brick Sub-Floor

Fig 15.2:  Strip Footing, Concrete PowerBlock Sub-Floor

Tie down rods/engineering restraints must be embedded into the footing and pass up through the sub floor and into the Hebel PowerBlock work.

Table 15.1 Top-Plate & Hold-Down selection

Wind Classification Top Plate & Hold-Down
Tile Roof Sheet Roof
N1 A / B / C B / C
N2 A / B / C D / F
N3 D / F D / F
N4 D / F D / F
N5 E / G E / G
N6 E / G E / G
C1 D / F D / F
C2 E / G E / G
C3 E / G E / G
C4 G G
Legend
A 90×45 F7 timber top plate / 700mm deep strap @ 1200mm ctrs.
B 90×45 F17 timber top plate / 1700mm deep strap @ 2400mm ctrs.
C 90×45 F17 timber top plate / Ф12mm rod @ 2400mm ctrs
D 90×45 F17 timber top plate / Ф12mm rod @ 1200mm ctrs.
E 90×45 F17 timber top plate / Ф12mm rod @ 900mm ctrs.
F 100x50x3.0 RHS top plate / Ф12mm rod @ 2400mm ctrs.
G 100x50x3.0 RHS top plate / Ф12mm rod @ 1200mm ctrs.

Fig 15.3 Hold Down Detail for Reinforced Bracing Walls

Table 15.2 provides ultimate racking capacities of reinforced 150mm and 250mm Hebel PowerBlock walls. The reinforcement is N12 bar or 12mm threaded rod at nominal 1000mm centres. The reinforcement must be tied to the footings and wall top plate through the bond beam. Walls resisting racking forces should be evenly distributed within a house and spaced at a maximum of 8.0m. Ceiling and floor diaphragms must be adequately tied to walls to ensure transfer of forces through to the footings. For more information about bracing, refer to Section 6.11 of the Hebel Technical Manual.

Fig 15.4 Roof Top to Plate Fixing to Hebel Wall – Strap (elevation)

Top Plate Hold-Down

Two tie-down methods are provided in this design guide.

1. Strap – 30×0.8mm cut into inside face of external wall min. 700mm deep.

2. 12mm threaded rod continuous from footing through bond beam to top plate.

Fig 15.5 Roof Top Plate Fixing to Hebel Wall-Tie-Down Rod (elevation) Three top plates options are provided in this design guide:

1. 90×45 F7 timber 2. 90×45 F17 timber 3. 100x50x3.0 RHS

The type of hold-down method and spacing depends on the top plate, roof type/span, and wind classification. Refer to Table 15.1 for specifications. For high wind areas, the bracing design is likely to require tie-down rods which will drive that as the hold-down method.

Table  15.2 Reinforced Wall – N12 Bars at Nom. 1000mm CTRS

Wall
Length
(mm)
Min. No. of
N12 Bars
Ultimate Racking Capacity (kN)
150mm PowerBlock 250mm PowerBlock
900 2 5 6
1200 2 8 8
1800 3 16 18
2400 3 24 25
3000 4 36 38
3600 5 45 46
4800 6 54 56
6000 7 63 66

Base of Wall

Fig 15.6 Hebel PowerBlock work on Stiffened Raft Slab Edge Foundation (elevation)

 

Fig 15.7  Concrete PowerBlock Sub-Floor Detail (elevation)

 

Fig 15.8  Double Brick Sub-Floor Detail (elevation)

 

Fig 15.9 Ring Beam Internal Non-Loadbearing Wall (elevation) (No tie down – as specified by design engineer)

 

Top of Wall

Fig 15.10 Roof Top Plate Fixing to Hebel Wall – Tie-Down Rod ( elevation)

 

Fig 15.11 Internal Hebel Load Bearing Wall and Timber Floor Frame Junction (elevation)

Wall Junctions

Fig 15.12  External Wall and Internal Partition Wall Junction  (plan)

 

Fig 15.13  External Corner with Control Joint (plan)

 

Control Joints

Fig 15.14 Control Joint detail (elevation)

Fig 15.15 Typical Bond Beam Control Joint – elevation (Location where no tie down required – as specified by engineer)

 

Fig 15.16 Typical Ring Beam Control Joint – elevation (Location where no tie down required – as specified by engineer)

 

Fig 15.17 Typical Control Joint – plan

 

Fig 15.18 Hebel PowerBlock work Typical Movement Joint Detail (elevation)

 

Fig 15.19 Hebel PowerBlock work Typical Movement Joint Detail (plan)

 

Fig 15.20 Built-in Column Detail (plan)

 

Fig 15.21 Built-in Column Detail (elevation)

PLEASE NOTE:
For all other design details (eg. door, window, floor panels) please follow the previous construction details in Section 14.0)

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Appendix A – Carpet Installation

Panel Surface Preparation

Sweep the floor surface to remove debris and loose particles. Expose all surface blemishes such as chips, cracks, gaps, ridges or the like. Fill all unacceptable locations with an appropriate and compatible patching compound such as Hebel Patch or levelling compound as required. Ensure panels are then dry.

Carpet Smooth Edge Installation

Installation of Carpet Smooth Edge (Gripper) is to be in accordance with AS/NZS 2455.1:1995.

Installation of carpet gripper prior to laying carpet requires the use of specifically selected nails or course threaded screws. Standard fixings supplied with the carpet gripper are not suitable for fixing to Hebel PowerFloor panels. Carpet gripper strips are available without factory supplied nails. For carpet gripper installation near the panel edge, only glue is recommended. If relying on glue only, the carpet can not be stretched until the glue is set after approximately 24 hours.

Table A.1 – Carpet Smooth Edge Fixings
Fixing Type Description Application
Method
Installation Notes
Twist Nails 51mm domehead twist nail Coil Nail Gun(Refer to Fig A.1) The head of the twist nailshould finish flush with
the surface of the gripper
strip
Screws Type 17 point- course thread
No. 8g x 50mm
– Countersinking
screw
Makita 6834Auto Feed
Screwdriver
(Refer to Fig A.2)
The head of the twist nailshould finish flush with
the surface of the carpet
gripper strip
Screws Type 17 pointTrimhead deckScrew.
4.2 x 50mm
4.2 x 65mm
Quickdrive auto feed The head of the screwshould be flush with the
smooth edge

Underlay Installation

Minimum medium duty underlay is to be used. No other special requirements.

Carpet Installation

As per carpet manufacturer’s guidelines. No other special requirements.

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4 Construction Details QT Eco Series

4.1 Slab & Floor

All foundations must comply with the relevant standards and local authority requirements, with appropriate consideration given to soil type. QT EcoSeries Wall Panel is suitable for construction on concrete slab or suspended floors. The concrete slab can either be rebated or non-rebated. The slab rebate will need to be a minimum of 50mm below floor level and 100mm above paved level or 150mm above ground level (See local standards). To ensure a flush finish, the width of the slab rebate needs to allow for the thickness of the coating system, the thickness of the panel (40mm or 50mm), and the size of the extended wall cavity 20 – 50mm (30mm nom). Minimum ground clearances, must be maintained at all times during the life of the building. Insufficient clearance from the ground to the bottom of the wall panels will affect long-term durability.

4.3 Windows

Wherever possible windows and associated flashings should be installed prior to the installation of the QT EcoSeries Wall Panel. When ordering the window frame it is essential to plan where the window flange will be positioned either flush with the stud frame, flush with battens or even over the panel.

All materials that are susceptible to deterioration due to plastics migration or alkalinity of cement base products must be protected (check with product manufacturer).

4.4 Decorative Mouldings

To provide added design flexibility, decorative mouldings or features can be made using QT EcoSeries Wall Panels. The panel can be cut into bands or laminate multiple layers and shape to achieve the desired profile. Once installed, a coating system would then be applied. Alternatively, a wide range of decorative mouldings are available from various manufacturers.

QT EcoSeries Wall Panels can be cut into bands that can be installed around windows, doors, along horizontal control joints, etc to enrich the aesthetics of the project. They are installed so the top and bottom edge (bevelled at 15 degrees) falls away from the wall. Where bands meet, they should be cut at a 45˚ angle, across the face of the corbel to help conceal the join and increase the adhered surface bond. Bands are bonded into place with polyurethane foam and corbel screws or nails to mechanically fix the bands until the foam is set.

 

4.5 Doors

Door framing must be fixed in position prior to the installation of the QT EcoSeries Wall Panels. The door framing will allow the panel to be cut and installed neat but independent of the frame. Door frames must be fixed to the structural framing. Decorative mouldings can be used to emphasize the door opening.

All materials that are susceptible to deterioration due to plastics migration or alkalinity of cement base products must be protected (check with product manufacturer).


4.7 Wall to Roof

Wall to roof details can often be unsightly as they are easily seen and hard to conceal without compromising the weathertighness of the dwelling. Because of its visibility, it is essential to create clean straight lines either by using a uPVC moulding or cover flashings.

Parapet Type 2

4.8 Soffit & Eaves

The eaves or roof overhang play a significant role in the comfort performance of the building. Eaves or overhangs are used to shade the walls from the summer sun, while capturing the sun’s heat in the winter. Eaves will reduce glancing light, which highlights the wall surface. Glancing light is the light that is nearly parallel to the surface of the wall and casts visible shadows and uneven projections of the surface finish QT EcoSeries Wall Panels can be installed to suit various soffit designs and details.

 

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