ASTM D6662-22

Standard Specification for Polyolefin-Based Plastic Lumber Decking Boards

ABSTRACT
This specification covers polyolefin-based plastic lumber products for use as exterior residential decking boards. Plastic lumber products are currently made predominantly with recycled polyolefin plastics (in particular high-density polyethylene) where the products are more or less non-homogenous in the cross-section. However, this specification is also potentially applicable to similar manufactured plastic products made from other plastic and plastic composite materials that have non-homogenous cross-sections. Performance requirements to which the products should adhere to are flexural properties (allowable flexural stress, and effective modulus of elasticity and adjustment for creep), dimensional stability during thermal expansion, weatherability (surface appearance and flexural property changes, and hygrothermal cycling), fire properties, and slip resistance. Also detailed here is a procedure to calculate recommended span lengths for spacing of support joists.
SCOPE
1.1 This specification covers polyolefin-based plastic lumber products for use as exterior residential decking boards.  
1.2 Plastic lumber products are currently made predominantly with recycled polyolefin plastics (in particular high-density polyethylene) where the products are more or less non-homogenous in the cross-section. However, this specification is also potentially applicable to similar manufactured plastic products made from other plastic and plastic composite materials that have non-homogenous cross-sections.  
1.3 This specification details a procedure to calculate recommended span lengths for spacing of support joists. This procedure was developed using experimental data from a typical unreinforced plastic lumber made predominantly from recycled high-density polyethylene. The methodology to develop span lengths for other types and compositions of plastic lumber is detailed in Appendix X1 of this standard.  
1.4 The values are stated in inch-pound units, as these are currently the most common units used by the construction industry. Equivalent SI units are indicated in parentheses. However, the units stated for irradiance exposure in the weatherability section (6.3) are in SI units as these are the units commonly used for testing of this type.  
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
Note 1: There is no similar or equivalent ISO Standard.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Mar-2022
• ICS: 91.100.99 - Other construction materials
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.20 - Plastic Lumber

Relations

• Refers: ASTM D883-24 - Standard Terminology Relating to Plastics
• Effective Date: 01-Feb-2024
• Refers: ASTM D6109-24 - Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastic Lumber and Related Products
• Effective Date: 01-Feb-2024
• Refers: ASTM E84-23d - Standard Test Method for Surface Burning Characteristics of Building Materials
• Effective Date: 01-Dec-2023
• Refers: ASTM D883-23 - Standard Terminology Relating to Plastics
• Effective Date: 01-Nov-2023
• Refers: ASTM D6112-23 - Standard Test Methods for Compressive and Flexural Creep and Creep-Rupture of Plastic Lumber and Shapes
• Effective Date: 01-Nov-2023
• Refers: ASTM D2565-23 - Standard Practice for Xenon-Arc Exposure of Plastics Intended for Outdoor Applications
• Effective Date: 01-Oct-2023
• Refers: ASTM E84-23c - Standard Test Method for Surface Burning Characteristics of Building Materials
• Effective Date: 01-Sep-2023
• Refers: ASTM E108-20a - Standard Test Methods for Fire Tests of Roof Coverings
• Effective Date: 01-Apr-2020
• Refers: ASTM E108-20 - Standard Test Methods for Fire Tests of Roof Coverings
• Effective Date: 15-Mar-2020
• Refers: ASTM D883-20 - Standard Terminology Relating to Plastics
• Effective Date: 01-Jan-2020
• Refers: ASTM D883-19c - Standard Terminology Relating to Plastics
• Effective Date: 01-Aug-2019
• Refers: ASTM E84-19b - Standard Test Method for Surface Burning Characteristics of Building Materials
• Effective Date: 01-Jul-2019
• Refers: ASTM E84-19a - Standard Test Method for Surface Burning Characteristics of Building Materials
• Effective Date: 15-Apr-2019
• Refers: ASTM D883-19a - Standard Terminology Relating to Plastics
• Effective Date: 15-Apr-2019
• Refers: ASTM D6109-19 - Standard Test Methods for Flexural Properties of Unreinforced and Reinforced Plastic Lumber and Related Products
• Effective Date: 01-Apr-2019

Overview

ASTM D6662-22 is a standard specification established by ASTM International for polyolefin-based plastic lumber decking boards used in exterior residential applications. This specification addresses the requirements for decking products manufactured predominantly with recycled polyolefin plastics, such as high-density polyethylene (HDPE), often resulting in non-homogenous cross-sections. The standard is also applicable to similar plastic products made from other plastic or composite materials with non-homogenous profiles.

The document outlines essential performance characteristics, including flexural properties, dimensional stability, weatherability, fire performance, and slip resistance, ensuring that plastic decking boards meet the demands of outdoor residential environments.

Key Topics

• Material Composition
  Polyolefin-based plastic lumber, commonly made from recycled HDPE, with options for other plastics or composites.
• Performance Requirements
  • Flexural Properties: Specified minimums for flexural strength and modulus of elasticity, with considerations for long-term creep.
  • Dimensional Stability: Controls on expansion and contraction due to temperature fluctuations, referencing linear coefficient of expansion.
  • Weatherability: Testing protocols to verify resistance to UV exposure, moisture, and hygrothermal cycling.
  • Fire Properties: Maximum flame spread index requirements for decking applications.
  • Slip Resistance: General guidance on surface treatments; no specific numeric criteria set.
• Span Calculations Methodology for determining recommended maximum span lengths for support joists, guided by section modulus, allowable stress, and creep adjustment factors.
• Dimensional Specifications Outlines permissible variations in thickness, width, length, flatness, squareness, and crook, with references to traditional lumber sizing and industry tolerances.
• Quality Assurance Emphasizes regular sampling, inspection, and record-keeping to assure product consistency and compliance.

Applications

• Residential Decking:
  ASTM D6662-22 specifically targets polyolefin-based plastic lumber products used as exterior residential decking boards. Typical use cases include patios, walkways, pool decks, and other outdoor structures requiring durable, weather-resistant decking materials.
• Sustainable Construction:
  The standard encourages the use of recycled plastics (notably recycled HDPE), supporting green building initiatives and sustainability goals.
• Custom Decking Solutions:
  Manufacturers may design boards in proprietary dimensions or match standard lumber sizes, offering flexibility for architects and builders. The standard covers both general retail distribution and project-specific material acquisition.
• Regulatory Compliance:
  Meeting ASTM D6662-22 helps ensure decking materials comply with building codes related to fire performance and structural integrity.

Related Standards

• ASTM D883: Terminology Relating to Plastics
• ASTM D2565: Xenon-Arc Exposure of Plastics for Outdoor Applications
• ASTM D4329: Fluorescent UV Exposure of Plastics
• ASTM D6109: Flexural Properties of Plastic Lumber
• ASTM D6112: Creep Testing for Plastic Lumber
• ASTM D6341: Linear Coefficient of Thermal Expansion of Plastic Lumber
• ASTM E84: Surface Burning Characteristics of Building Materials
• ASTM E108: Fire Tests of Roof Coverings
• ASTM G151, G154, G155: Practices for Laboratory Light Source Exposures
• ASTM D2898: Accelerated Weathering of Fire-Retardant-Treated Wood

These documents support the testing, classification, and performance criteria referenced in ASTM D6662-22, ensuring a comprehensive approach to evaluating plastic lumber decking boards.

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Keywords: ASTM D6662-22, polyolefin-based plastic lumber, plastic decking, HDPE decking boards, recycled plastic decks, exterior residential decks, decking standard, weather resistance, slip resistance, fire performance, lumber span calculation, synthetic decking compliance.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:D6662 −22
Standard Specification for
Polyolefin-Based Plastic Lumber Decking Boards
This standard is issued under the fixed designation D6662; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 2. Referenced Documents
1.1 This specification covers polyolefin-based plastic lum- 2.1 The following documents of the issue in effect on the
dateofmaterialpurchaseformapartofthisspecificationtothe
ber products for use as exterior residential decking boards.
extent referenced herein:
1.2 Plastic lumber products are currently made predomi-
2.2 ASTM Standards:
nantly with recycled polyolefin plastics (in particular high-
D883Terminology Relating to Plastics
density polyethylene) where the products are more or less
D2565Practice for Xenon-Arc Exposure of Plastics In-
non-homogenous in the cross-section. However, this specifica-
tended for Outdoor Applications
tion is also potentially applicable to similar manufactured
D2898 Practice for Accelerated Weathering of Fire-
plastic products made from other plastic and plastic composite
Retardant-Treated Wood for Fire Testing
materials that have non-homogenous cross-sections.
D2915Practice for Sampling and Data-Analysis for Struc-
1.3 This specification details a procedure to calculate rec-
tural Wood and Wood-Based Products
ommended span lengths for spacing of support joists. This
D4329Practice for Fluorescent Ultraviolet (UV) Lamp Ap-
procedure was developed using experimental data from a
paratus Exposure of Plastics
typical unreinforced plastic lumber made predominantly from
D5033GuideforDevelopmentofASTMStandardsRelating
recycled high-density polyethylene. The methodology to de-
to Recycling and Use of Recycled Plastics (Withdrawn
velop span lengths for other types and compositions of plastic 3
2007)
lumber is detailed in Appendix X1 of this standard.
D6109TestMethodsforFlexuralPropertiesofUnreinforced
1.4 The values are stated in inch-pound units, as these are and Reinforced Plastic Lumber and Related Products
currently the most common units used by the construction D6112Test Methods for Compressive and Flexural Creep
industry. Equivalent SI units are indicated in parentheses. and Creep-Rupture of Plastic Lumber and Shapes
However, the units stated for irradiance exposure in the D6341Test Method for Determination of the Linear Coef-
ficient of Thermal Expansion of Plastic Lumber and
weatherabilitysection(6.3)areinSIunitsasthesearetheunits
commonly used for testing of this type. Plastic Lumber Shapes Between –30 and 140°F (–34.4
and 60°C)
1.5 This standard does not purport to address all of the
E84Test Method for Surface Burning Characteristics of
safety concerns, if any, associated with its use. It is the
Building Materials
responsibility of the user of this standard to establish appro-
E108Test Methods for Fire Tests of Roof Coverings
priate safety, health, and environmental practices and deter-
G151PracticeforExposingNonmetallicMaterialsinAccel-
mine the applicability of regulatory limitations prior to use.
erated Test Devices that Use Laboratory Light Sources
NOTE 1—There is no similar or equivalent ISO Standard.
G154Practice for Operating Fluorescent Ultraviolet (UV)
Lamp Apparatus for Exposure of Nonmetallic Materials
1.6 This international standard was developed in accor-
G155PracticeforOperatingXenonArcLampApparatusfor
dance with internationally recognized principles on standard-
Exposure of Materials
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
3. Terminology
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
3.1 Definitions:
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This specification is under the jurisdiction of ASTM Committee D20 on contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
PlasticsandisthedirectresponsibilityofSubcommitteeD20.20onPlasticLumber. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved April 1, 2022. Published April 2022. Originally the ASTM website.
approved in 2001. Last previous edition approved in 2017 as D6662-17. DOI: The last approved version of this historical standard is referenced on
10.1520/D6662-22. www.astm.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6662−22
3.1.1 plastic lumber, n—a manufactured product made pri- 4.1.9 Packing requirements,
marily from plastic materials (filled or unfilled), typically used 4.1.10 Palletization, if required,
as a building material for purposes similar to those of tradi- 4.1.11 Marking, if other than specified.
tional lumber, which is usually rectangular in cross-section.
4.2 If specific mechanical property values are not required
(Terminology D883)
by the purchaser (for example, when purchasing materials for
3.1.1.1 Discussion—Plastic lumber is typically supplied in
general retail sales distribution and not for a specific project),
sizes similar to those of traditional lumber board, timber and
the manufacturer shall provide minimum allowable design
dimension lumber; however the tolerances for plastic lumber
information, as would be determined under this specification,
and for traditional lumber are not necessarily the same.
to aid in the application of the decking board material by the
(Terminology D883)
end user.
3.1.2 resin, n—asolidorpseudosolidorganicmaterialoften
5. Dimensions and Permissible Variations
of high molecular weight, which exhibits a tendency to flow
when subjected to stress, usually has a softening or melting
It is permissible to produce decking boards either in sizes
range,andusuallyfracturesconchoidally.(TerminologyD883)
3.1.2.1 Discussion—In a broad sense, the term is used to that are similar to the standard dimensions of the wood
designate any polymer that is a basic material for plastics. industry, or to proprietary dimensions designed by manufac-
(1982) turers. This specification does not limit the dimensional
range of production. For reference, the standards of the
3.2 Definitions of Terms Specific to This Standard:
wood industry are as follows:
3.2.1 bulge—convex distortion (away from the center of the
cross-section) of the face of the board from a straight line 5.1 Thickness—Unless otherwise specified in 4.1.8, boards
shall be:
drawn from edge to edge across the width of the board.
Nominal (in.) Actual (in.) Tolerance (in.)
3.2.2 crook—distortion of the board in which there is a
3 1
1 ⁄4 ± ⁄16
deviation in a direction perpendicular to the edge from a
5 1
⁄4 1± ⁄16
straight line from end to end of the board. 1 1
21- ⁄2 ± ⁄16
Tolerance on thickness of boards thicker than 2 inches
3.2.3 cup—concave distortion (towards the center of the
cross-section) of the face of the board from a straight line (nominal) shall be 6 ⁄16 inch.
drawn from edge to edge across the width of the board.
5.2 Width of Boards—Unless otherwise specified in para-
3.2.4 edge—the side of a rectangular-shaped board corre-
graph 4.1.8, board widths shall be:
sponding to the thickness of the board.
Nominal (in.) Actual (in.) Tolerance (in.)
1 1
32- ⁄2 ± ⁄16
3.2.5 face—the side of a rectangular-shaped board corre-
1 1
43- ⁄2 ± ⁄16
sponding to the width of the board. 1 1
65- ⁄2 ± ⁄16
1 1
87- ⁄4 ± ⁄16
3.2.6 thickness—the lesser dimension of the cross-sectional
1 1
10 9- ⁄4 ± ⁄16
profile of a rectangular-shaped board.
1 1
12 11- ⁄4 ± ⁄16
3.2.7 width—the greater dimension of the cross-sectional Toleranceonwidthofboardswiderthan12inches(nominal)
profile of a rectangular-shaped board.
shall be 6 ⁄16 inch.
3.3 Additional definition of terms applying to this specifi- 5.3 Length of Boards—unless otherwise specified in 4.1.7,
1 1
cation appear in Terminology D883 and D5033.
boards up to 20 feet shall have tolerances of + ⁄2 inch or - ⁄16
1 1
inch. Over 20 feet, the tolerances will be + ⁄2-inch or - ⁄16 inch
4. Ordering Information
per 20-ft of length or fraction thereof. Measurement of lengths
to be made at 73 6 2 °F and relative humidity of 50 65%.
4.1 The information contained in this specification is in-
tended to be helpful to producers, distributors, regulatory
5.4 Flatness Tolerance—Board shall be flat with maximum
agencies and users. The information can also promote under-
cuporbulgeintheboardfacelimitedtothetolerancesinTable
standing between purchasers and sellers. The purchaser shall
1. Linear interpolation of the values is acceptable for dimen-
state whether this specification is to be used, select the
sions other than listed.
preferred options permitted herein, and include the allowable
5.5 Squareness—Unless a specially shaped member is
design information in the invitation to bid and purchase order
specified, the cross-section of all boards shall be visually
from the following:
rectangular (that is, the face and edge of the board are
4.1.1 Title, number and date of this specification,
perpendicular to each other) and suited for the intended
4.1.2 Minimum allowable bending strength and allowable
purpose.
bending stiffness,
4.1.3 Percent recycled content (if requested),
4.1.4 Flame spread index,
TABLE 1 Cup or Bulge Tolerances Relative to Nominal Width of
4.1.5 Color,
the Board Face
4.1.6 Quantity in lineal feet,
Face Width, in. #4 in. 6 in. 8 in. 10 in. 12 in.
4.1.7 Cut length,
1 1 1 3 1
Tolerance ⁄32 in. ⁄16 in. ⁄8 in. ⁄16 in. ⁄4 in.
4.1.8 Cross-sectional dimensions,
D6662−22
TABLE 3 Number of Specimens Required to Establish the Mean
5.6 Crook—Crook shall conform to the tolerances in Table
Value with an Error of ± 5% with 75% Confidence for Various
2. Linear interpolation of the values is acceptable for dimen-
Coefficients of Variation (COV) in the Data Set
sions other than listed.
COV Range, % 10–15 >15–20 >20–25 >25
5.7 Tongue and Groove—Boards shall be without tongue No. of Specimens, N 15 23 34 ~60
andgrooveunlessotherwisespecifiedin4.1.8.Becauseofload
transfer between adjacent boards, the methodology and equa-
TABLE 4 Value of K for Establishing the Lower 5% Lower
tions presented in section 6.1.4 for determining recommended
Tolerance Limit with 75% Confidence for Various Sample Sizes
maximumspanlengthsarenotapplicabletotongueandgroove
No. of Specimens, N 15 30 Infinite
boards. Manufacturers of tongue and groove decking boards
Value of K 1.991 1.869 1.645
shall provide recommended span lengths based on sound
engineering practice, taking into account some of the issues
described in 6.1.4 below, as well as previous, in-service
6.1.4 below. Alternatively, use span lengths less than 16 in. on center as
performance history.
needed.
NOTE4—ConcurrenttothedevelopmentofthisspecificationforPlastic
6. Performance Requirements
Lumber Decking, a Standard Guide for the Design and Construction of
Plastic Lumber Decking is being developed by Section D20.20.01 (under
6.1 Flexural Properties:
the Subcommittee D20.20 on Plastic Products). This Standard Guide is
6.1.1 Test Procedure—D6109.
expected to be available sometime after this Specification has been
6.1.2 Specimens Tested—Aminimum of 15 specimens shall
approved and in use.
be tested.
6.1.4 Span Lengths—Recommendedmaximumspanlengths
6.1.3 Criteria—(1) The mean value of the secant flexural
shall be determined using the following equations:
modulus at 1% outer fiber strain estimated statistically to
For concentrated loads on boards which are continuous over
within 5% with 75% confidence shall equal or exceed 50 000
a minimum of two spans (such as decking boards) as shown in
psi. Table 3 shows the number of specimens required to
Fig. 1, the maximum recommended span shall be limited by
establish the mean value at 75% confidence interval with 6
either the stress or the deflection formula as follow, whichever
5% error using Practice D2915.(2) The 5% lower tolerance
provides the lesser span:
limitat75%confidenceflexuralstressat3%outerfiberstrain
Stress Formula:
shall equal or exceed 1000 psi. If any specimen fails prior to
L 5 64SF ' / 13P (1)
~ ! ~ !
b
reaching3%strain,thentheflexuralstrengthatfailureforthat
specimen shall equal or exceed 1000 psi. The 5% lower
Deflection Formula:
tolerance limit at 75% confidence is computed by subtracting
L 5 @ 67E'I / Pkα #2 (2)
~ ! ~ !
K-times the standard deviation from the mean value, where K
is tabulated in statistics handbooks (and in Table 3 of Practice
For distributed (or uniform) loads on boards which are
D2915) as a factor for a one-sided tolerance limit for the
continuous over a minimum of two spans (such as decking
distribution. Table 4 shows the value of K for several sample
boards) as shown in Fig. 2, the maximum span shall be limited
sizes.
by either the stress or the deflection formula as follow,
whichever provides the lesser span:
NOTE 2—Many standards require a minimum sample size of approxi-
Stress Formula:
mately 30 to balance testing costs against the large reductions in the
allowable values for very small sample sizes.
L 5 8SF ' 144 / qb 2 (3)
@~ !~ ! ~ !#
NOTE 3—A16 in. on center joist spacing is considered typical standard b
spacing for residential deck construction. While 50 000 psi is given as a
Deflection Formula:
minimum flexural modulus, a modulus greater than 50 000 psi is
potentially required for some decking board sizes in order to meet this
L 5 185E'I 144 / qb kα 3 (4)
@~ !~ ! ~ !#
spacing when determining span lengths per the guidance presented in
TABLE 2 Crook Tolerances Relative to Nominal Length and Width
of the Board
Length in Feet #4in. 6in. 8 in. Width 10 in. 12 in.
Width Width Width Width
3 1 3 1 1
4–6 ⁄8 in. ⁄4 in. ⁄16 in. ⁄8 in. ⁄8 in.
1 1 3 1 3
8 ⁄2 in. ⁄2 in. ⁄8 in. ⁄4 in. ⁄16 in.
3 5 1 7 3
10 ⁄4 in. ⁄8 in. ⁄2 in. ⁄16 in. ⁄8 in.
7 13 3 9
12 1 in. ⁄8 in. ⁄16 in. ⁄4 in. ⁄16 in.
1 1 7 3
14 1 ⁄4 in. 1 ⁄8 in. 1 in. ⁄8 in. ⁄4 in.
1 3 1 7
16 1 ⁄2 in. 1 ⁄8 in. 1 ⁄8 in. 1 in. ⁄8 in. FIG. 1Schematic of Concentrated Load on Boards that are Con-
tinuous Over Two Spans
D6662−22
TABLE 6 Temperature Factor, C
T
Temperature, °F C
T
32 1.71
63 1.14
73 1.00
100 0.63
122 0.43
140 0.30
FIG. 2Schematic of Distributed Load on Boards that are Continu-
ous Over Two Spans
Use linear interpolation to estimate C for any other temperature value.
T
The Load Duration Factors C and Temperature Factor C were developed
D T
using one typical unreinforced polyolefin-based plastic lumber. The methodology
to obtain these factors for boards of other composition is outlined in Appendix X1.
where:
L = computed span length, in.,
where:
S = section modulus, in. ,
F = the5%lowertolerancelimitat75%confidenceofthe
bt
F ' = allowable flexural stress as computed in 6.1.4.1, psi,
b
flexuralstressat3%outerfiberstraindeterminedfrom
P = concentrated load, lb,
flexure tests conducted in accordance with Test
E' = effective modulus of elasticity as computed in 6.1.4.2,
Method D6109, and
psi,
0.3 = factor to convert the 3 minute test value to a ten year
I = moment of inertia, in. ,
normaldurationvalue(thatis,aflexuralstressequalto
k = factor used to limit deflection to L/k (for example
30%ofF will induce a 3% outer fiber strain in ten
L/360 with k = 360; or L/120 with k = 120),
bt
years).
q = uniformly distributed load, lb/sq-ft,
b = actual board width, in., and NOTE 6—The attached commentary in Appendix X1 provides a more
detailed description of the development of C ,C and 0.3 factors above,
α = Creep Adjustment Factor = 1.5. D T
basedonexperimentaldataontypicalplasticlumber.Ageneralprocedure
NOTE 5—The attached commentary in Appendix X1 provides a
to develop these factors for other types of plastic lumber is also provided
rationale for the Creep Adjustment Factor, α.
in Appendix X1.
6.1.4.1 Allowable Flexural Stress—The allowable flexural
6.1.4.2 Effective Modulus of Elasticity and Adjustment for
stress, F ', of the decking board is given as follows:
b
Creep—The effective modulus of elasticity, E', shall be deter-
F ' 5 F /FS ·C ·C (5)
~ !
b b D T mined as follows:
where:
E' 5 E·C (7)
~ !
T
F = the base flexural stress value for plastic lumber made
b
where:
of HDPE-type polyolefins for normal duration loading
E = the secant flexural modulus as defined in section 6.1,
(10 yr. duration), psi,
psi, and
FS = Factor of Safety = 1.5,
C = Temperature Factor, Table 6.
T
C = Load Duration Factor for flexural stress, presented in
D
The deflection, ∆ , for the decking board can then be
Fig. 3 and Table 5, depends on the shortest-duration
T
calculated as follows:
load in combination, applied either cumulatively or
continuously, and
∆ 5∆ ·α (8)
T e1
C = Temperature Factor, Table 6.
T
where, ∆ , the instantaneous elastic deflection for the cases
e1
F , the base flexural stress value for plastic lumber made of
b
in Fig. 1 is given as
HDPE type polyolefins, is determined as follows:
∆ 5 PL / 67E'I forconcentratedloads (9)
@ # @ #
e1
F 5 F ·0.3 (6)
b bt
∆ 5 @qbL #/@~144!·~185E'I!# fordistributedloads (10)
e1
Fordistributedloadingatanaverageambienttemperatureof
90°Fthemaximumcreepdeflectionofthedeckingboardsshall
TABLE 5 Load Duration Factor, C
D
not exceed L/240.
Duration of Load Load Duration Factor
Impact Load—1 s 4.81
NOTE 7—An example problem for the case of distributed loading is
1 min 3.62
described in Appendix X2, Table X2.1.
3 min 3.34
Wind/Seismic Load—10 min 3.04 6.2 Dimensional Stability—Thermal Expansion:
1 h 2.64
6.2.1 Test Procedure—D6341.
6 h 2.28
6.2.2 Specimens Tested—Aminimum of 15 specimens shall
1 day 2.04
Construction Load—7 days 1.73
be tested to establish the average value.
Snow Load—2 months 1.44
Report the measured coefficient of thermal expansion in the
1 year 1.22
longitudinal direction to two significant figures for use in deck
Floor Load—10 years 1.00
Permanent Load—30 years 0.91
design calculations.
NOTE 8—This value has the potential to be of significant importance
Use linear interpolation to estimate C for any other duration of load, noting that
D
the abscissa in Fig. 3 is on a logarithmic scale. when the plastic lumber decking boards are used with other dissimilar
D6662−22
FIG. 3Load Duration Factor for Plastic Lumber
materialsinvolvingdifferentialthermalexpansionundervaryingtempera-
6.3.1.4 Criteria of Degradation: 6.3.1.4.1 Exposed samples
ture conditions. For tongue and groove boards, the transverse thermal
shall be free of any visual surface changes such as peeling,
expansion coefficient is also occasionally needed to estimate required
chipping, cracking, flaking, pitting and non-uniform color
spacing between boards.
changes.
6.3 Weatherability
6.3.2 Test Procedure for Flexural Property Changes:
6.3.1 Test Procedure for Surface Appearance Changes:
6.3.2.1 Exposure Conditions: 6.3.2.1.1 Specimens to be
6.3.1.1 Exposure Conditions: 6.3.1.1.1 Specimens to be
tested shall be exposed to fluorescent UVA-340 radiation in
tested shall be exposed to the xenon arc light source with
accordance with Practices G151, G154 and D4329 Procedure
daylight filters in accordance with Practices G151, G155 and
7.2.2 Cycle B.
D2565.
6.3.2.1.2 Use the following exposure conditions (control
6.3.1.1.2 Use the following exposure conditions (control
setpoints and control tolerances) for a total period of 2000
setpoints and control tolerances) for a total period of 2000
hours, cycling between:
hours continuous light, cycling between:
8 hours light only
2 hours light only Irradiance: 0.72 ± 0.2 W/(m ·nm) @340 nm
Irradiance: 0.7 ± 0.02 W/(m ·nm) @340 nm
Uninsulated Black Panel 158 ± 5°F (70 ± 2.8°C)
or Temperature:
77.0 ± 4.5 W/m @300–400 nm
4 hours no light with condensation
or Irradiance: Not applicable
736.0 ± 44.0 W/m @300–800nm
Uninsulated Black Panel Not applicable
Humidity (if used): 50 ± 5 % RH Temperature:
Uninsulated Black Panel 158 ± 4°F (70 ± 2.2°C)
6.3.2.1.3 The surface of the plastic lumber specimens will
Temperature:
needtobeimmersedinorsprayedwithwaterinordertoassure
2 hours light with water spray (on the exposed surface)
Irradiance: 0.7 ± 0.02 W/(m ·nm) @340 nm
a wet surface during the no-light portion of the test cycle. The
or
2 plastic lumber specimens are too thick and too great of an
77.0 ± 4.5 W/m @300–400 nm
or insulator to expect water to condense on the face of the
736.0 ± 44.0 W/m @300–800
specimen during the no light cycle.
nm
6.3.2.2 Specimens Tested: 6.3.2.2.1 Full Member
Humidity: Not applicable
Uninsulated Black Panel Not applicable
Boards—15 representative specimens shall be prepared and
Temperature:
tested in flexure as described in Test Method D6109 with the
NOTE 9—Immersion can be used as an alternative method to water loadingnosesontheunexposedsidesothattheexposedsideis
spray to introduce moisture to the material surface.
under tensile stress.
6.3.2.3 Period of Exposure—Specimenstobetestedshallbe
6.3.1.2 Specimens Tested: 6.3.1.2.1 Coupon Specimens—
exposed for a period of 2000 hours in accordance with section
Triplicate specimens of a size required to fit into the standard
6.3.2.1.
weathering chamber specimen holder.
6.3.1.3 Period(s) of Exposure—Specimenstobetestedshall
NOTE10—TheBuildingOfficialsandCodeAdministrators(BOCA)has
be exposed for a period of 2000 hours in accordance with
accepted a screening test with Test Method D4329 at 1080 hour exposure
section 6.3.1.1. in approving polyolefin based decking boards per BOCA International
D6662−22
Evaluation Research Report 97-63, December 1999.
extent that it interferes with the effect of the gas flame on the
NOTE 11—As detailed in Appendix X3, there is experimental data that
test specimen or (b) portions of the test specimen melt or drop
indicate that outdoor weathering over an 11 year period has negligible
to the furnace floor to the extent that progression of the flame
effect on the flexural strength and stiffness of polyolefin based plastic
front on the test specimen is inhibited. Appendix X1 of Test
lumber decking boards. Thus, a 2000 hour screening test, such as that
Method E84 provides guidance on mounting methods.
described above, can only be used to identify the products that are most
susceptible to UVdegradation and with the potential to deteriorate in two
6.4.3 Products shall have a flame spread index no greater
years or less under actual outdoor exposure.
than 200 when tested in accordance with Test Method E84.
6.3.2.4 Criteria of Degradation—Theflexuralsecantmodu-
NOTE 12—For combustible construction, codes often require fire
lus shall retain 90% of the average value at 75% confidence
performanceatleastequivalenttothatofwood.Amaximumflamespread
when tested without exposure.
index of 200 when tested in accordance with Test Method E84 is
considered to be equivalent to that of wood. For outdoor applications,
6.3.3 Hygrothermal Cycling:
there is no requirement specified for smoke developed index.
6.3.3.1 Test Procedure—Specimens shall also be prepared
NOTE 13—Fire retardants are available to increase the resistance to
as described in Test Method D6109. Each specimen shall then
ignitabilityandflamespreadofplasticlumberandshallbeincorporatedas
be weighed to the nearest 0.00022 lb (0.1 g). Specimens shall
needed.
then be totally submerged underwater (using weights to hold
6.4.4 The plastic lumber industry has developed a qualifi-
down, if necessary) for a period of 24 h. After removal from
cation fire test based on end-use of the material in decking.
water,eachspecimenshallthenbedriedwithadryclothonthe
This method, a modification of Test Methods E108 originally
outside surfaces and weighed again within 20 min. Specimens
intended for roofing materials, is presented in Appendix X4
which exceed a 1% weight gain shall be resoaked until such
along with a commentary for its use.
time as the weight changes less than 1% per 24 hour period.
6.5 Slip Resistance:
Such specimens will then be considered to have reached
6.5.1 There is currently no universal consensus of require-
moisture absorption equilibrium. Upon reaching this equilib-
ments for slip resistance for residential decking regardless of
rium the specimens shall be frozen to -20 °F (-29 °C) for 24 h,
thematerialofconstruction.Overtheyears,avarietyofASTM
thenreturnedtoroomtemperature.Thisprocesscomprisesone
test methods have been developed to measure the slip resis-
hygrothermal cycle.
tance or the coefficient of friction of various materials.
The above procedure shall be repeated two more times, for
However, the test results can be significantly influenced by
atotalofthreecyclesofwatersubmersion,moistureabsorption
climaticandinterfacialconditions,whichthedifferentmethods
equilibrium, and freezing.After completion of these steps, the
do not necessarily take into account. The existing ASTM test
specimens shall be returned to room temperature and tested as
methods are, therefore, not considered sufficient to establish
described in Test Method D6109.
minimum slip resistance criteria for publication in this plastic
6.3.3.2 Specimens Tested—A minimum of 15 specimens
lumber decking board standard.
shall be prepared as per Test Method D6109 and tested.
6.3.3.3 Criteria—Note any obvious physical changes that
NOTE 14—ASTM is currently coordinating slip resistance specification
issuesataSocietylevel.CommitteeSectionD20.20.01onPlasticLumber
occur as a result of the hygrothermal cycling. The flexural
willcontinuetolooktotherecommendationsfromthiseffortforguidance
secant modulus and the greater of the stress level at 3% strain
on this issue.
or the stress at fracture as defined in Test Method D6109 shall
6.5.2 As with all types of decking materials, in some cases
retain 90% of the average value at 75% confidence when
egress areas will require specific surface treatments in order to
tested without hygrothermal cycling.
reduce the possibility of accidental slipping.
6.3.4 Weathering for Code Applications:
6.3.4.1 When plastic lumber materials are intended for use
7. Specimen Conditioning
in applications where code requirements apply, materials shall
meet the performance requirements for weathering (including 7.1 Conditioning of Specimens for Tests—Unless specifi-
cally stated otherwise, all specimens shall be conditioned and
exposure to temperature and moisture) contained in MethodA
from Practice D2898, as applicable to the materials and the tested in accordance with the appropriate test method.
conditions of use, except as indicated in 6.3.4.2.
8. Workmanship, Finish, and Appearance
6.3.4.
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D6662 − 17 D6662 − 22
Standard Specification for
Polyolefin-Based Plastic Lumber Decking Boards
This standard is issued under the fixed designation D6662; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This specification covers polyolefin-based plastic lumber products for use as exterior residential decking boards.
1.2 Plastic lumber products are currently made predominantly with recycled polyolefin plastics (in particular high-density
polyethylene) where the products are more or less non-homogenous in the cross-section. However, this specification is also
potentially applicable to similar manufactured plastic products made from other plastic and plastic composite materials that have
non-homogenous cross-sections.
1.3 This specification details a procedure to calculate recommended span lengths for spacing of support joists. This procedure was
developed using experimental data from a typical unreinforced plastic lumber made predominantly from recycled high-density
polyethylene. The methodology to develop span lengths for other types and compositions of plastic lumber is detailed in Appendix
X1 of this standard.
1.4 The values are stated in inch-pound units, as these are currently the most common units used by the construction industry.
Equivalent SI units are indicated in parentheses. However, the units stated for irradiance exposure in the weatherability section
(6.3) are in SI units as these are the units commonly used for testing of this type.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
NOTE 1—There is no similar or equivalent ISO Standard.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 The following documents of the issue in effect on the date of material purchase form a part of this specification to the extent
referenced herein:
2.2 ASTM Standards:
This specification is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.20 on Plastic Lumber.
Current edition approved March 1, 2017April 1, 2022. Published March 2017April 2022. Originally approved in 2001. Last previous edition approved in 20132017 as
D6662 - 13.D6662 - 17. DOI: 10.1520/D6662-17.10.1520/D6662-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6662 − 22
D883 Terminology Relating to Plastics
D2565 Practice for Xenon-Arc Exposure of Plastics Intended for Outdoor Applications
D2898 Practice for Accelerated Weathering of Fire-Retardant-Treated Wood for Fire Testing
D2915 Practice for Sampling and Data-Analysis for Structural Wood and Wood-Based Products
D4329 Practice for Fluorescent Ultraviolet (UV) Lamp Apparatus Exposure of Plastics
D5033 Guide for Development of ASTM Standards Relating to Recycling and Use of Recycled Plastics (Withdrawn 2007)
D6109 Test Methods for Flexural Properties of Unreinforced and Reinforced Plastic Lumber and Related Products
D6112 Test Methods for Compressive and Flexural Creep and Creep-Rupture of Plastic Lumber and Shapes
D6341 Test Method for Determination of the Linear Coefficient of Thermal Expansion of Plastic Lumber and Plastic Lumber
Shapes Between –30 and 140°F (–34.4 and 60°C)
E84 Test Method for Surface Burning Characteristics of Building Materials
E108 Test Methods for Fire Tests of Roof Coverings
G151 Practice for Exposing Nonmetallic Materials in Accelerated Test Devices that Use Laboratory Light Sources
G154 Practice for Operating Fluorescent Ultraviolet (UV) Lamp Apparatus for Exposure of Nonmetallic Materials
G155 Practice for Operating Xenon Arc Lamp Apparatus for Exposure of Materials
3. Terminology
3.1 Definitions:
3.1.1 plastic lumber, n—a manufactured product made primarily from plastic materials (filled or unfilled), typically used as a
building material for purposes similar to those of traditional lumber, which is usually rectangular in cross-section. (Terminology
D883)
3.1.1.1 Discussion—
Plastic lumber is typically supplied in sizes similar to those of traditional lumber board, timber and dimension lumber; however
the tolerances for plastic lumber and for traditional lumber are not necessarily the same. (Terminology D883)
3.1.2 resin, n—a solid or pseudo solid organic material often of high molecular weight, which exhibits a tendency to flow when
subjected to stress, usually has a softening or melting range, and usually fractures conchoidally. (Terminology D883)
3.1.2.1 Discussion—
In a broad sense, the term is used to designate any polymer that is a basic material for plastics. (1982)
3.2 Definitions of Terms Specific to This Standard:
3.2.1 bulge—convex distortion (away from the center of the cross-section) of the face of the board from a straight line drawn from
edge to edge across the width of the board.
3.2.2 crook—distortion of the board in which there is a deviation in a direction perpendicular to the edge from a straight line from
end to end of the board.
3.2.3 cup—concave distortion (towards the center of the cross-section) of the face of the board from a straight line drawn from
edge to edge across the width of the board.
3.2.4 edge—the side of a rectangular-shaped board corresponding to the thickness of the board.
3.2.5 face—the side of a rectangular-shaped board corresponding to the width of the board.
3.2.6 thickness—the lesser dimension of the cross-sectional profile of a rectangular-shaped board.
3.2.7 width—the greater dimension of the cross-sectional profile of a rectangular-shaped board.
3.3 Additional definition of terms applying to this specification appear in Terminology D883 and D5033.
4. Ordering Information
4.1 The information contained in this specification is intended to be helpful to producers, distributors, regulatory agencies and
The last approved version of this historical standard is referenced on www.astm.org.
D6662 − 22
users. The information can also promote understanding between purchasers and sellers. The purchaser shall state whether this
specification is to be used, select the preferred options permitted herein, and include the allowable design information in the
invitation to bid and purchase order from the following:
4.1.1 Title, number and date of this specification,
4.1.2 Minimum allowable bending strength and allowable bending stiffness,
4.1.3 Percent recycled content (if requested),
4.1.4 Flame spread index,
4.1.5 Color,
4.1.6 Quantity in lineal feet,
4.1.7 Cut length,
4.1.8 Cross-sectional dimensions,
4.1.9 Packing requirements,
4.1.10 Palletization, if required,
4.1.11 Marking, if other than specified.
4.2 If specific mechanical property values are not required by the purchaser (for example, when purchasing materials for general
retail sales distribution and not for a specific project), the manufacturer shall provide minimum allowable design information, as
would be determined under this specification, to aid in the application of the decking board material by the end user.
5. Dimensions and Permissible Variations
It is permissible to produce decking boards either in sizes that are similar to the standard dimensions of the wood industry, or
to proprietary dimensions designed by manufacturers. This specification does not limit the dimensional range of production.
For reference, the standards of the wood industry are as follows:
5.1 Thickness—Unless otherwise specified in 4.1.8, boards shall be:
Nominal (in.) Actual (in.) Tolerance (in.)
3 1
1 ⁄4 ± ⁄16
5 1
⁄4 1 ± ⁄16
1 1
2 1- ⁄2 ± ⁄16
Tolerance on thickness of boards thicker than 2 inches (nominal) shall be 6 ⁄16 inch.
5.2 Width of Boards—Unless otherwise specified in paragraph 4.1.8, board widths shall be:
Nominal (in.) Actual (in.) Tolerance (in.)
1 1
3 2- ⁄2 ± ⁄16
1 1
4 3- ⁄2 ± ⁄16
1 1
6 5- ⁄2 ± ⁄16
1 1
8 7- ⁄4 ± ⁄16
1 1
10 9- ⁄4 ± ⁄16
1 1
12 11- ⁄4 ± ⁄16
Tolerance on width of boards wider than 12 inches (nominal) shall be 6 ⁄16 inch.
1 1
5.3 Length of Boards—unless otherwise specified in 4.1.7, boards up to 20 feet shall have tolerances of + ⁄2 inch or - ⁄16 inch. Over
1 1
20 feet, the tolerances will be + ⁄2-inch or - ⁄16 inch per 20-ft of length or fraction thereof. Measurement of lengths to be made at
73 6 2 °F and relative humidity of 50 6 5 %.
D6662 − 22
5.4 Flatness Tolerance—Board shall be flat with maximum cup or bulge in the board face limited to the tolerances in Table 1.
Linear interpolation of the values is acceptable for dimensions other than listed.
5.5 Squareness—Unless a specially shaped member is specified, the cross-section of all boards shall be visually rectangular (that
is, the face and edge of the board are perpendicular to each other) and suited for the intended purpose.
5.6 Crook—Crook shall conform to the tolerances in Table 2. Linear interpolation of the values is acceptable for dimensions other
than listed.
5.7 Tongue and Groove—Boards shall be without tongue and groove unless otherwise specified in 4.1.8. Because of load transfer
between adjacent boards, the methodology and equations presented in section 6.1.4 for determining recommended maximum span
lengths are not applicable to tongue and groove boards. Manufacturers of tongue and groove decking boards shall provide
recommended span lengths based on sound engineering practice, taking into account some of the issues described in 6.1.4 below,
as well as previous, in-service performance history.
6. Performance Requirements
6.1 Flexural Properties:
6.1.1 Test Procedure—D6109.
6.1.2 Specimens Tested—A minimum of 15 specimens shall be tested.
6.1.3 Criteria—(1) The mean value of the secant flexural modulus at 1 % outer fiber strain estimated statistically to within 5 %
with 75 % confidence shall equal or exceed 50 000 psi. Table 3 shows the number of specimens required to establish the mean
value at 75 % confidence interval with 6 5 % error using Practice D2915. (2) The 5 % lower tolerance limit at 75 % confidence
flexural stress at 3 % outer fiber strain shall equal or exceed 1000 psi. If any specimen fails prior to reaching 3 % strain, then the
flexural strength at failure for that specimen shall equal or exceed 1000 psi. The 5 % lower tolerance limit at 75 % confidence is
computed by subtracting K-times the standard deviation from the mean value, where K is tabulated in statistics handbooks (and
in Table 3 of Practice D2915) as a factor for a one-sided tolerance limit for the distribution. Table 4 shows the value of K for several
sample sizes.
NOTE 2—Many standards require a minimum sample size of approximately 30 to balance testing costs against the large reductions in the allowable values
for very small sample sizes.
NOTE 3—A16 in. on center joist spacing is considered typical standard spacing for residential deck construction. While 50 000 psi is given as a minimum
flexural modulus, a modulus greater than 50 000 psi is potentially required for some decking board sizes in order to meet this spacing when determining
span lengths per the guidance presented in 6.1.4 below. Alternatively, use span lengths less than 16 in. on center as needed.
NOTE 4—Concurrent to the development of this specification for Plastic Lumber Decking, a Standard Guide for the Design and Construction of Plastic
Lumber Decking is being developed by Section D20.20.01 (under the Subcommittee D20.20 on Plastic Products). This Standard Guide is expected to
be available sometime after this Specification has been approved and in use.
6.1.4 Span Lengths—Recommended maximum span lengths shall be determined using the following equations:
For concentrated loads on boards which are continuous over a minimum of two spans (such as decking boards) as shown in Fig.
1, the maximum recommended span shall be limited by either the stress or the deflection formula as follow, whichever provides
the lesser span:
Stress Formula:
L 5 64S F ' / 13P (1)
~ ! ~ !
b
Deflection Formula:
TABLE 1 Cup or Bulge Tolerances Relative to Nominal Width of
the Board Face
Face Width, in. #4 in. 6 in. 8 in. 10 in. 12 in.
1 1 1 3 1
Tolerance ⁄32 in. ⁄16 in. ⁄8 in. ⁄16 in. ⁄4 in.
D6662 − 22
TABLE 2 Crook Tolerances Relative to Nominal Length and Width
of the Board
Length in Feet #4 in. 6 in. 8 in. Width 10 in. 12 in.
Width Width Width Width
3 1 3 1 1
4–6 ⁄8 in. ⁄4 in. ⁄16 in. ⁄8 in. ⁄8 in.
1 1 3 1 3
8 ⁄2 in. ⁄2 in. ⁄8 in. ⁄4 in. ⁄16 in.
3 5 1 7 3
10 ⁄4 in. ⁄8 in. ⁄2 in. ⁄16 in. ⁄8 in.
7 13 3 9
12 1 in. ⁄8 in. ⁄16 in. ⁄4 in. ⁄16 in.
1 1 7 3
14 1 ⁄4 in. 1 ⁄8 in. 1 in. ⁄8 in. ⁄4 in.
1 3 1 7
16 1 ⁄2 in. 1 ⁄8 in. 1 ⁄8 in. 1 in. ⁄8 in.
TABLE 3 Number of Specimens Required to Establish the Mean
Value with an Error of ± 5 % with 75 % Confidence for Various
Coefficients of Variation (COV) in the Data Set
COV Range, % 10–15 >15–20 >20–25 >25
No. of Specimens, N 15 23 34 ~60
TABLE 4 Value of K for Establishing the Lower 5 % Lower
Tolerance Limit with 75 % Confidence for Various Sample Sizes
No. of Specimens, N 15 30 Infinite
Value of K 1.991 1.869 1.645
FIG. 1 Schematic of Concentrated Load on Boards that are Continuous Over Two Spans
L 5 67E'I / P kα 2 (2)
@~ ! ~ !#
For distributed (or uniform) loads on boards which are continuous over a minimum of two spans (such as decking boards) as
shown in Fig. 2, the maximum span shall be limited by either the stress or the deflection formula as follow, whichever provides
the lesser span:
Stress Formula:
L 5 @~8S F '!~144!/~qb!# 2 (3)
b
Deflection Formula:
L 5 @~185E'I!~144!/~qb kα!#3 (4)
where:
L = computed span length, in.,
S = section modulus, in. ,
F ' = allowable flexural stress as computed in 6.1.4.1, psi,
b
P = concentrated load, lb,
E' = effective modulus of elasticity as computed in 6.1.4.2, psi,
FIG. 2 Schematic of Distributed Load on Boards that are Continuous Over Two Spans
D6662 − 22
I = moment of inertia, in. ,
k = factor used to limit deflection to L/k (for example L/360 with k = 360; or L/120 with k = 120),
q = uniformly distributed load, lb/sq-ft,
b = actual board width, in., and
α = Creep Adjustment Factor = 1.5.
NOTE 5—The attached commentary in Appendix X1 provides a rationale for the Creep Adjustment Factor, α.
6.1.4.1 Allowable Flexural Stress—The allowable flexural stress, F ', of the decking board is given as follows:
b
F '5 F /FS ·C ·C (5)
~ !
b b D T
where:
F = the base flexural stress value for plastic lumber made of HDPE-type polyolefins for normal duration loading (10 yr.
b
duration), psi,
FS = Factor of Safety = 1.5,
C = Load Duration Factor for flexural stress, presented in Fig. 3 and Table 5, depends on the shortest-duration load in
D
combination, applied either cumulatively or continuously, and
C = Temperature Factor, Table 6.
T
F , the base flexural stress value for plastic lumber made of HDPE type polyolefins, is determined as follows:
b
F 5 F ·0.3 (6)
b bt
where:
F = the 5 % lower tolerance limit at 75 % confidence of the flexural stress at 3 % outer fiber strain determined from flexure
bt
tests conducted in accordance with Test Method D6109, and
0.3 = factor to convert the 3 minute test value to a ten year normal duration value (that is, a flexural stress equal to 30 % of F
bt
will induce a 3 % outer fiber strain in ten years).
NOTE 6—The attached commentary in Appendix X1 provides a more detailed description of the development of C , C and 0.3 factors above, based on
D T
experimental data on typical plastic lumber. A general procedure to develop these factors for other types of plastic lumber is also provided in Appendix
X1.
6.1.4.2 Effective Modulus of Elasticity and Adjustment for Creep—The effective modulus of elasticity, E', shall be determined as
follows:
E'5 E·C (7)
~ !
T
where:
E = the secant flexural modulus as defined in section 6.1, psi, and
C = Temperature Factor, Table 6.
T
The deflection, Δ , for the decking board can then be calculated as follows:
T
Δ 5 Δ ·α (8)
T e1
TABLE 5 Load Duration Factor, C
D
Duration of Load Load Duration Factor
Impact Load—1 s 4.81
1 min 3.62
3 min 3.34
Wind/Seismic Load—10 min 3.04
1 h 2.64
6 h 2.28
1 day 2.04
Construction Load—7 days 1.73
Snow Load—2 months 1.44
1 year 1.22
Floor Load—10 years 1.00
Permanent Load—30 years 0.91
Use linear interpolation to estimate C for any other duration of load, noting that
D
the abscissa in Fig. 3 is on a logarithmic scale.
D6662 − 22
TABLE 6 Temperature Factor, C
T
Temperature, °F C
T
32 1.71
63 1.14
73 1.00
100 0.63
122 0.43
140 0.30
Use linear interpolation to estimate C for any other temperature value.
T
The Load Duration Factors C and Temperature Factor C were developed
D T
using one typical unreinforced polyolefin-based plastic lumber. The methodology
to obtain these factors for boards of other composition is outlined in Appendix X1.
where, Δ , the instantaneous elastic deflection for the cases in Fig. 1 is given as
ele1
Δ 5 @PL #/@67E'I# for concentrated loads (9)
e1
Δ 5 @qbL #/@~144!·~185E'I!# for distributed loads (10)
e1
For distributed loading at an average ambient temperature of 90°F the maximum creep deflection of the decking boards shall
not exceed L/240.
NOTE 7—An example problem for the case of distributed loading is described in Appendix X2, Table X2.1.
6.2 Dimensional Stability—Thermal Expansion:
6.2.1 Test Procedure—D6341.
6.2.2 Specimens Tested—A minimum of 15 specimens shall be tested to establish the average value.
Report the measured coefficient of thermal expansion in the longitudinal direction to two significant figures for use in deck
design calculations.
NOTE 8—This value has the potential to be of significant importance when the plastic lumber decking boards are used with other dissimilar materials
involving differential thermal expansion under varying temperature conditions. For tongue and groove boards, the transverse thermal expansion coefficient
is also occasionally needed to estimate required spacing between boards.
6.3 Weatherability
6.3.1 Test Procedure for Surface Appearance Changes:
6.3.1.1 Exposure Conditions: 6.3.1.1.1 Specimens to be tested shall be exposed to the xenon arc light source with daylight filters
in accordance with Practices G151, G155 and D2565.
6.3.1.1.2 Use the following exposure conditions (control setpoints and control tolerances) for a total period of 2000 hours
continuous light, cycling between:
2 hours light only
Irradiance: 0.7 ± 0.02 W/(m ·nm) @340 nm
or
77.0 ± 4.5 W/m @300–400 nm
or
736.0 ± 44.0 W/m @300–800nm
Humidity (if used): 50 ± 5 % RH
Uninsulated Black Panel 158 ± 4°F (70 ± 2.2°C)
Temperature:
2 hours light with water spray (on the exposed surface)
Irradiance: 0.7 ± 0.02 W/(m ·nm) @340 nm
or
77.0 ± 4.5 W/m @300–400 nm
or
736.0 ± 44.0 W/m @300–800
nm
Humidity: Not applicable
Uninsulated Black Panel Not applicable
Temperature:
D6662 − 22
FIG. 3 Load Duration Factor for Plastic Lumber
NOTE 9—Immersion can be used as an alternative method to water spray to introduce moisture to the material surface.
6.3.1.2 Specimens Tested: 6.3.1.2.1 Coupon Specimens—Triplicate specimens of a size required to fit into the standard weathering
chamber specimen holder.
6.3.1.3 Period(s) of Exposure—Specimens to be tested shall be exposed for a period of 2000 hours in accordance with section
6.3.1.1.
6.3.1.4 Criteria of Degradation: 6.3.1.4.1 Exposed samples shall be free of any visual surface changes such as peeling, chipping,
cracking, flaking, pitting and non-uniform color changes.
6.3.2 Test Procedure for Flexural Property Changes:
6.3.2.1 Exposure Conditions: 6.3.2.1.1 Specimens to be tested shall be exposed to fluorescent UVA-340 radiation in accordance
with Practices G151, G154 and D4329 Procedure 7.2.2 Cycle B.
6.3.2.1.2 Use the following exposure conditions (control setpoints and control tolerances) for a total period of 2000 hours,
cycling between:
8 hours light only
Irradiance: 0.72 ± 0.2 W/(m ·nm) @340 nm
Uninsulated Black Panel 158 ± 5°F (70 ± 2.8°C)
Temperature:
4 hours no light with condensation
Irradiance: Not applicable
Uninsulated Black Panel Not applicable
Temperature:
6.3.2.1.3 The surface of the plastic lumber specimens will need to be immersed in or sprayed with water in order to assure a
wet surface during the no-light portion of the test cycle. The plastic lumber specimens are too thick and too great of an insulator
to expect water to condense on the face of the specimen during the no light cycle.
6.3.2.2 Specimens Tested: 6.3.2.2.1 Full Member Boards—15 representative specimens shall be prepared and tested in flexure as
described in Test Method D6109 with the loading noses on the unexposed side so that the exposed side is under tensile stress.
6.3.2.3 Period of Exposure—Specimens to be tested shall be exposed for a period of 2000 hours in accordance with section 6.3.2.1.
NOTE 10—The Building Officials and Code Administrators (BOCA) has accepted a screening test with Test Method D4329 at 1080 hour exposure in
approving polyolefin based decking boards per BOCA International Evaluation Research Report 97-63, December 1999.
NOTE 11—As detailed in Appendix X3, there is experimental data that indicate that outdoor weathering over an 11 year period has negligible effect on
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the flexural strength and stiffness of polyolefin based plastic lumber decking boards. Thus, a 2000 hour screening test, such as that described above, can
only be used to identify the products that are most susceptible to UV degradation and with the potential to deteriorate in two years or less under actual
outdoor exposure.
6.3.2.4 Criteria of Degradation—The flexural secant modulus shall retain 90 % of the average value at 75 % confidence when
tested without exposure.
6.3.3 Hygrothermal Cycling:
6.3.3.1 Test Procedure—Specimens shall also be prepared as described in Test Method D6109. Each specimen shall then be
weighed to the nearest 0.00022 lb (0.1 g). Specimens shall then be totally submerged underwater (using weights to hold down, if
necessary) for a period of 24 h. After removal from water, each specimen shall then be dried with a dry cloth on the outside surfaces
and weighed again within 20 min. Specimens which exceed a 1 % weight gain shall be resoaked until such time as the weight
changes less than 1 % per 24 hour period. Such specimens will then be considered to have reached moisture absorption
equilibrium. Upon reaching this equilibrium the specimens shall be frozen to -20 °F (-29 °C) for 24 h, then returned to room
temperature. This process comprises one hygrothermal cycle.
The above procedure shall be repeated two more times, for a total of three cycles of water submersion, moisture absorption
equilibrium, and freezing. After completion of these steps, the specimens shall be returned to room temperature and tested as
described in Test Method D6109.
6.3.3.2 Specimens Tested—A minimum of 15 specimens shall be prepared as per Test Method D6109 and tested.
6.3.3.3 Criteria—Note any obvious physical changes that occur as a result of the hygrothermal cycling. The flexural secant
modulus and the greater of the stress level at 3 % strain or the stress at fracture as defined in Test Method D6109 shall retain 90 %
of the average value at 75 % confidence when tested without hygrothermal cycling.
6.3.4 Weathering for Code Applications:
6.3.4.1 When plastic lumber materials are intended for use in applications where code requirements apply, materials shall meet
the performance requirements for weathering (including exposure to temperature and moisture) contained in Method A from
Practice D2898, as applicable to the materials and the conditions of use, except as indicated in 6.3.4.2.
6.3.4.2 When plastic lumber materials have no content of cellulosic materials, weathering in accordance with Practice D2898 is
not required.
6.4 Fire Properties:
6.4.1 The flame spread index of plastic lumber decking boards shall be determined by testing in accordance with Test Method E84.
6.4.2 The test specimen shall either be self-supporting by its own structural characteristics or held in place by added supports along
the test specimen surface. The test specimen shall remain in place throughout the test duration. Test results are invalid if one of
the following occurs during the test: (a) the test specimen sags from its position in the ceiling to such an extent that it interferes
with the effect of the gas flame on the test specimen or (b) portions of the test specimen melt or drop to the furnace floor to the
extent that progression of the flame front on the test specimen is inhibited. Appendix X1 of Test Method E84 provides guidance
on mounting methods.
6.4.3 Products shall have a flame spread index no greater than 200 when tested in accordance with Test Method E84.
NOTE 12—For combustible construction, codes often require fire performance at least equivalent to that of wood. A maximum flame spread index of 200
when tested in accordance with Test Method E84 is considered to be equivalent to that of wood. For outdoor applications, there is no requirement specified
for smoke developed index.
NOTE 13—Fire retardants are available to increase the resistance to ignitability and flame spread of plastic lumber and shall be incorporated as needed.
6.4.4 The plastic lumber industry has developed a qualification fire test based on end-use of the material in decking. This method,
a modification of Test Methods E108 originally intended for roofing materials, is presented in Appendix X4 along with a
commentary for its use.
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6.5 Slip Resistance:
6.5.1 There is currently no universal consensus of requirements for slip resistance for residential decking regardless of the material
of construction. Over the years, a variety of ASTM test methods have been developed to measure the slip resistance or the
coefficient of friction of various materials. However, the test results can be significantly influenced by climatic and interfacial
conditions, which the different methods do not ne
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