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STANDARD MEDIUM DENSITY FIBREBOARD	Data Sheet 8 February 2008

Scope

This Data Sheet applies to standard, general purpose, Medium Density Fibreboard (MDF) with a density range of about 650 to 850 kg/m3. The Australian Standard (AS/NZS 1859.2) includes three other general purpose dryprocessed fibreboards – Ultra Low Density, Low Density and High Density. These are special products and their availability and application should be confirmed from manufacturers.

Standard MDF is designed for general purpose interior use only and is not suitable for exterior use or interior areas where wetting or high humidity conditions are likely.

Manufacture

Medium Density Fibreboard is manufactured from fibres or fibre bundles produced from wood by a mechanical refining process carried out at elevated temperature. A synthetic resin binder, typically urea formaldehyde, is added to impart strength properties and paraffin wax to provide protection against accidental water spillage.

Product Range

Standard MDF is manufactured in the following thicknesses:

Mechanical & Physical Properties

Table 1
Typical Property Values for Australian Producers

Dimensional Tolerances

The following dimensional tolerances are typical for MDF produced by AWPA members:

Moisture Properties

MDF, like other wood based products and many other building materials, will respond to changes in relative humidity of the surrounding air. Board dimensions are closely related to moisture content. Conditions likely to change the moisture content above or below the 7 - 12% range normally applying at dispatch from the factory should be conditioned to reach the moisture content in which it is to be used. Moisture contents will normally be in the range 10 - 12% when used in buildings intended for human occupancy.

Measurement of moisture content may be achieved by weighing and drying or by using an electric moisture meter.

Absorption & Swelling

The most significant effect of moisture absorption by MDF is that of swelling in the thickness. Where this
takes place, there will be a small amount of residual swelling after the product has dried out. Standard MDF should not be used in applications where there is a risk of contact with water. MR MDF should be used in these cases, or the risk removed by adequate sealing of faces and edges.

Dimensional Changes

When Standard MDF is exposed to changes in relative humidity, it changes in length about 0.03 - 0.06% for every 1% change in moisture content. In thickness, the panel will change by 0.3 - 0.5% for each change in moisture content. These values relate to a linear hygro expansion of 0.3% from 30% to 90% relative humidity and a thickness expansion of 6% from 30% to 90% relative humidity.

Thermal Properties

The thermal conductivity of MDF varies slightly with thickness with the usual range being 0.05-0.08
kcal/mh°C (0.12 - 0.15 W/m°K).

Like natural timber, MDF has a low thermal capacity. Within the normal range of temperature variation, MDF is dimensionally stable and its strength unaffected.

Acoustic Properties

Sound transmission loss is a property that depends greatly on the building element and its method of
installation. However, as a general figure, MDF of a thickness of 16mm and thicker should achieve a sound
transmission class of STC - 29.

FIRE BEHAVIOUR

Fire Resistance

Fire resistance relates to the period for which an element of construction will resist the passage whether a material will allow a fire to spread of flame, remain free from collapse and insulate against an excessive
temperature rise on the unexposed face. The property relates to a building element and its details of
construction, rather than a particular material. MDF reacts generally to fire like natural timber. The rate of
burning is similar and it does not shatter or delaminate.

Combustibility

MDF is combustible. The degree of combustibility depends on type and density of the board. As with timber, burning will be limited by the formation of charcoal on the surface but shrinkage will tend to cause failure at joints, unless proper consideration has been given to design.

Fire Hazard

Fire hazard refers to the surface burning characteristics of a material and indicates whether a material will
allow a fire to spread quickly. Smoke developed is also part of the hazard assessment. Fire hazard is
measured by procedures laid down in AS1530 Part 3 and is expressed as indices. Typical results for
Standard MDF are:

Specific building regulations indicate where materials with specific early fire hazard indices can be used.

Heat and Smoke Release Tests to AS/NZS 3837.1998 – Standard MDF

This test is relevant when the panel is to be used for wall and ceiling applications. In this test, AWPA
members’ raw MDF achieved the following results:

Biodeterioration

As with most other wood products, MDF is susceptible to attack from wood destroying fungi and termites.
However, moisture contents of over 18% must be maintained before fungal attack can occur. Under such
conditions, Standard MDF should not be used. Post treatment with brush on preservatives will protect
against the growth of surface mould which can disfigure the surface appearance. Attack by wood destroying beetles is possible, but unlikely in Australia.

Health and Safety Information

Normal health and safety precautions should be taken when working with wood panel products. Machine
tools should be fitted with dust extractors and work areas kept clean. If dust levels exceed The National
Occupational Health & Safety Commission’s standards, the wearing of dust mask (AS/NZS1715 and
AS/NZS1716) and safety glasses (AS/NZS1337) is recommended.

Storage and work areas should be adequately ventilated. If large quantities of Medium Density Fibreboard
are stored in non-ventilated areas, formaldehyde emissions could accumulate to levels which may irritate
some people.

For further information, please contact one of the manufacturers listed below for a copy of a Material Safety Data Sheet or download from www.woodpanels.org.au.

Whilst the information contained herein is based on data which to the best of our knowledge is
reliable and accurate as of the date hereof, no responsibility can be accepted by us for errors or
omissions. Since the information contained herein may be applied under conditions beyond our
control, no responsibility can be accepted by us for any loss or damage caused by any person acting or refraining from acting as a result of this information.

Published by the Australian Wood Panels Association Incorporated, PO Box 158, Coolangatta Qld
4225, February 2008.