ISO 19821:2017

INTERNATIONAL ISO
STANDARD 19821
First edition
2017-11
Determination of span rating for
natural fibre-reinforced plastic
composite (NFC) deck boards
Détermination de la portée nominale des lames de platelage en
composite plastique renforcé de fibres naturelles (NFC)
Reference number
ISO 19821:2017(E)
©
ISO 2017

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ISO 19821:2017(E)

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© ISO 2017, Published in Switzerland
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ISO 19821:2017(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test specimen . 2
5 Sampling . 2
6 Conditioning . 2
7 Evaluation methods of performance . 2
7.1 General . 2
7.2 Temperature and moisture effects . 2
7.2.1 Temperature effect . 2
7.2.2 Moisture effect . 3
7.2.3 Acceptance criteria . 3
7.3 Weatherproofing . 3
7.3.1 Test method . 3
7.3.2 Acceptance criteria . 3
7.4 Freeze-thaw resistance . 4
7.4.1 Test method . 4
7.4.2 Acceptance criteria . 4
7.5 Biodeterioration . 4
7.5.1 General. 4
7.5.2 Fungal decay resistance . 4
7.5.3 Termites . 4
7.6 Creep-recovery . 5
7.6.1 Test method . 5
7.6.2 Acceptance criterion . 5
7.7 Creep-rupture . 5
7.7.1 Test method . 5
7.7.2 Acceptance criterion . 5
7.8 Mechanical fastener holding . 5
7.9 Slip resistance . 6
8 Determination of span rating . 6
8.1 Deck board span rating . 6
8.2 Two-span adjustment . 6
9 Report . 7
9.1 Test report . 7
9.2 Product description . 7
9.3 Installation instructions . 7
Annex A (informative) Adjustment factor — Examples . 8
Annex B (normative) Two-span test method . 9
Bibliography .10
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ISO 19821:2017(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
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organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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URL: www.iso.org/iso/foreword.html
This document was prepared by Technical Committee ISO/TC 61, Plastics, Subcommittee SC 11,
Products.
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ISO 19821:2017(E)

Introduction
Natural fibre-reinforced plastic composites (NFC) are made of one or several cellulosic materials
combined with one or several thermoplastics. Currently, cellulosic materials mainly come from
different natural plant sources and the most common thermoplastics, including virgin and recycled
forms, are polyethylene, polypropylene and polyvinyl chloride. In the past, these composites used to be
called wood plastic composites (WPC). In this document, NFC is used instead of WPC, in line with the
terminology used in ISO 16616.
The production of NFC in the thermoplastics industry has gained much acceptance in recent years and
is expected to keep growing rapidly. This type of composite material has become an important family
of engineering materials due to the increasing need for sustainable and biodegradable renewable
materials, which are known as “green composites.” NFC has sustainable character due to the presence
of wood as a natural component, which enables environmental protection and minimization of waste
formation. Such materials offer significant advantages which justify their use.
NFC has recently found wide applications in construction and decoration areas including decking,
fencing, flooring, landscaping, railings, window framing, and roof tiles. Meanwhile it is also applied for
packaging, automotive industries, furniture and other items.
For deck boards used in outdoor environments, some performance measurements, such as temperature
and moisture effects, ultraviolet resistance, freeze-thaw resistance, etc., are used in the determination
of the span rating in order to assist in the proper installation and using. However, due to the lack of
a unified testing method to evaluate a span rating indicating the board’s ability to comply with
functions identified for its specific end use, therefore, it would be required to establish an ISO standard
for removing the barriers of deck boards in the application and sales, and encouraging technology
development in the NFC production field.
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INTERNATIONAL STANDARD ISO 19821:2017(E)
Determination of span rating for natural fibre-reinforced
plastic composite (NFC) deck boards
1 Scope
This document specifies the procedures to establish a span rating for natural fibre-reinforced plastic
composite (NFC) deck boards and deck boards used as stair treads, provided that the stair treads are
produced from the same materials and processing techniques as the deck boards. This document covers
test methods of performance, acceptance criteria and determination of span rating. It is intended to
establish the basis for code recognition of deck boards used in exterior applications where combustible
construction is allowed.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 291, Plastics — Standard atmospheres for conditioning and testing
ISO 4892-2:2013, Plastics — Methods of exposure to laboratory light sources — Part 2: Xenon-arc lamps
ISO 16616:2015, Test methods for natural fibre-reinforced plastic composite (NFC) deck boards
EN 15534-1:2014, Composites made from cellulose-based materials and thermoplastics (usually
called wood-polymer composites (WPC) or natural fibre composites (NFC)) — Part 1: Test methods for
characterization of compounds and products
ASTM D7032-17, Standard Specification for Establishing Performance Ratings for Wood-Plastic Composite
and Plastic Lumber Deck Boards, Stair Treads, Guards, and Handrails
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
natural fibre-reinforced plastic composite
NFC
product made thereof being the result of the combination of one or several cellulosic materials with one
or several thermoplastics
3.2
flexural strength
maximum load achieved by the test specimen during flexural test, and reported as modulus of
rupture (MOR)
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ISO 19821:2017(E)

3.3
flexural stiffness
value calculated from a linear least squares fit of the stress-strain curve over the range of 10 % to 40
% of ultimate stress, and reported as either modulus of elastic (MOE) or MOE × moment of inertia (EI)
Note 1 to entry: If the cross-section of deck boards is complicated to calculate moment of inertia, it is better to
use EI to indicate flexural stiffness.
3.4
span rating
maximum centre-to-centre support spacing for the specified end use
4 Test specimen
Test specimens with the original thickness and width of the product are used in the tests unless
otherwise specified. In general, test specimens of the product are rectangular in cross-section for deck
boards and stair treads.
5 Sampling
It is important to select test specimens that reflect the variability of the population. It is essential to
consider batch-to-batch and shift-to-shift variability when sampling actual production. Test specimens
shall be selected from several production runs of a given item.
6 Conditioning
Prior to testing, all specimens shall be conditioned to
...