5. hempcrete installation: floors

H e m p c r e t e A u s t r a l i a M a n u a l 1

5.1 Hempcrete insulation between suspended floor constructions

5.1.1 Mix

This floor mix has the following properties;

Density: 275 - 295kg/m3

41 - 44kg/m2 (150mm thickness)

Elasticity: 3 MPa after 90 days

Resistance to compression: 0.1-0.15 MPa after 90 days

R rating: 3.2

5. Hempcrete Installation: floors

material for 1m3 for 1m2 (150mm thick insulation)

Insulcore/Hemp wood 1000Ltr (100kg) 158Ltr (15.8kg)

Insulime 125kg 20kg (0.8kg bag)

Water 175 - 200Ltr 27.5 - 31.5Ltr

proportion of aggregates (Hemp fragments) within total dry weight

dry density (for information)

Minimal Aggregate

(strong mixture)

10% 1000 Kg/m3

Maximum Aggregate

(weak mixture)

50% 200 Kg/m3


5: Hempcrete Installation: Floors

5.1.2 Thermal Resistance Table

1m3 gives 950Ltr of mixed hempcrete material.

The true calculation for the required m3 in material (hemp) is m3 X 1.05 plus an allowance for waste.

At all times the floor structure should be engineered to take into account the additional weight of the hempcrete insulation.

Engineered I joists are very suitable for hempcrete infill insulation. If hardwood is used a rough surface is preferred to create stronger adhesion.

Mixing method as described in Chapter 3: Installation General.

5.2 Hempcreteappliedinfloor-cavity of suspended floors

5.2.1 Preparation

1 A minimum layer of 100-150mm hempcrete is recommended.

2 Ensure positioning of electrical conduits and plumbing is complete and affixed properly to the carrier.

3 Application is the easiest from the top.

4 Ensure the carrier (cladding or formwork under the floor joists) of the hempcrete insulation is fastened appropriately. See previous Chapter section 4.7.2 Permanent Formwork on page 10.

5.2.2 Supporting materials / formwork affixed to the joists or perpendicular battens:

1 composite wood sheets not exceeding 12mm thickness. See Figure 2.

2 magnesium board not exceeding 12mm thickness. See Figure 4.

3 magnesium board placed between the I joists. See Figure 3.

4 bamboo or reed mats. See Figure 5.

5 timber tongue and groove ceiling cladding. See Figure 1.

6 formwork securely attached.

thickness (mm) 100 150 200 250 300

R (m2kw-1) R 1.1 R 1.6 R 2.1 R 2.7 R 3.2



5.3 application

5.3.1 Checklist

Before commencing with the infill of hempcrete following checklist should be completed:

1 Has the floor been inspected and signed off?

2 Are all electrical and plumbing services in place?

3 Check again that ceiling light fittings and smoke alarms are in place before formwork is attached.

4 Is all plumbing lagged and/or coated with bitumen paint?

5.3.2 Applying Hempcrete

1 Wet all timber surfaces before application as timber will extract moisture from the hempcrete.

2 Transport mixed product to the formwork.

3 Carefully dump mix in the cavities between joists.

4 Place and press a single layer of hempcrete gently between the joists and the formwork (either permanent or temporary). This can be done by hand wearing rubber gloves or with buckets and shovels.

5 Light tamping with emphasis on the sides and bottom of the formwork is necessary to fill all cavities and gaps. The tamping co-efficient is 10mm on 200mm loose hempcrete. Light tamping will result in the most efficient insulation and will require the least amount of material. Use a hammer-like timber tamper.

Tamping

■ Eliminates voids adjacent to the formwork surface creating the bottom surface of the floor.

■ Fills in cavities around battens and services, and ensures that electrical boxes for power points and lights switches are surrounded by sufficient hempcrete material.

■ Tamping should be performed gently and lightly to maintain the looseness of the hemp.

■ Tamping the hempcrete between formwork and frame is unnecessary.

■ Is done with a tamping tool. Refer to Tools diagram in Chapter 4. Floor surface should not be laid within 28 days of installing hempcrete insulation.

Floor covering installation must be as per AS 3.4.3.

5.3.3 Floor Finishes

All finishing methods and products should conform to Australian Standards.

1 floorboards on joists - floorboards can be glued onto the joists after hempcrete has been positioned between the joists.

2 floatingfloor - can be mounted as per standard floating floor.

3 Gluedfloatingfloor - a floating floor can be glued onto a particle board underlay.

4 flexiblefloorcovering - such as linoleum requires a sturdy underlay installed as per AS1859 AS 1860, AS 2485 AS 2269.

5.3.4 Drying

After application allow the hempcrete to dry for 30-60 days, depending on local weather conditions. Supply traffic areas with planks to avoid over compaction.

Ensure sufficient ventilation in the building and do not force dry. Maintain humidity or keep hempcrete covered it is drying too quickly.

Caution

Fast drying, which occurs when wind combines with full sun, should be carefully monitored as there is a higher risk of retaining inner core moisture.

Partial covering might be preferential.

Each situation must be assessed individually.


5.4 floor examples

Figure 1:

Parquet on to hempcrete insulated floor.

The permanent timber plank / floor boards formwork becomes the finished ceiling of the space below. A breathable coating should be used on the timber ceiling.

Underlay Particle Board

Hempcrete

Parquet

Timber Ceiling

Cladding

I JoistSupport Batten

Figure 2:

Floor boards on to hempcrete insulated floor made of I Joists.

The permanent timber particle board formwork becomes the finished ceiling of the space below. This can be painted with a breathable paint.

Underlay

Hempcrete


Tongue & Groove Flooring

Particle Board

Underfloor Batten

Figure 3:

Parquet on to hempcrete insulated floor with different ceiling finish.

The permanent magnesium formwork fitted in between the joists ribs, becomes the finished ceiling of the space below. This can be painetd with breathable paints.


Hempcrete

Parquet

Magnesium BoardI Joist



Figure 4:

Linoleum on to hempcrete insulated floor.

The permanent magnesium formwork becomes the finished ceiling of the space below. This can be painted with breathable paint.


Hempcrete

Magnesium Board


Linoleum

Figure 5:

Parquet on to hempcrete insulated floor, with bamboo ceiling.

The permanent bamboo formwork becomes the finished ceiling of the space below. A render finish is recommended.


Hempcrete

Bamboo Matting


Parquet

DisclaimerThis document is intended to give general guidelines and practical information to the builder. It does not constitute a specification. Neither Hempcrete Australia Pty Ltd or St. Astier Limes can accept any responsibility or liability on the use and application of their products, errors or omissions in this document, loss, damage, injury or adverse outcome of any kind resulting from the use of the information contained in this document or reliance upon it.

Readers are advised to seek specific professional advice from Hempcrete Australia relating to their construction project and circumstances before embarking on any construction work.

All care has been taken to guarantee the accuracy of the information.

Drawings and models representing technical details are indicative and suggestions only.

All diagrams and pictures are the property of Hempcrete Australia, and are subject to Copyright 2012 ©. No part of this book may be reproduced without prior written permission of Hempcrete Australia Pty. Ltd.

energy saving eco building

Hempcrete Australia Pty Ltd

Director: Johan Tijssen

ABN: 76 155 685 859

Web: www.hempcrete.com.au

Email: [email protected]

Office: 07 5429 6634 International: +61 7 5429 6634

Mobile: 0416 331 008 +61 4 16 331 008

Fax: 07 5429 6635 +61 7 5429 6635

Technical support

Please get in touch with us if you require further information - contacts below.

The Hempcrete Australia website installers’ login is a rich source of information.

Street address:

8 Thynne Court,

Maleny Qld 4552 AUSTRALIA

Postal address:

P.O. Box 1227

Maleny Qld 4552 AUSTRALIA

5. hempcrete installation: floors

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