AN SI A135.4-2004 

Approved March 11, 2004 

Basi Hardboard
 
ANSI A135.4-2004, Basic Hardboard 

American 

National 

Standard 

Published by 

Approval of an American Standard requires verification by the 

American National Standards Institute (ANSI) that the 

requirements for due process, consensus, and other criteria for 

approval have been met by the standard's developer. 

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Board of Standards Review, substantial agreement has been 

reached by directly and materially affected interests. Substantial 

agreement means much more than a simple majority, but not 

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objections be considered, and that a concerted effort be made 

toward their resolution. 

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their existence does not in any respect preclude anyone, whether 

they have approved the standards or not, from manufacturing, 

marketing, purchasing, or us ing products, processes, or procedures 

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an interpretation of any American National Standard. Moreover, no 

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an American National Standard in the name of the American 

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Standards Institute require that action be taken periodically to 

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Composite Panel Association 

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Printed in the United States of America 
ANSI A135.4-2004 Basic Hardboard 

Abstract	 This Standard defines hardboard, covers requirements and 

test methods for water absorption, thickness swelling, 

modulus of rupture, tensi le strength, surface finish, 

dimensions, squareness, edge straightness, and moisture 

content of five classes of bas ic hardboard. Where 

appropriate, test methods in ASTM D 1037 are required. 

Methods of identifying hardboard that conforms to this 

Standard are provided. 

(This Foreword is not a part of American National Standard Foreword for Basic Hardboard.) Basic hardboard has numerous uses, 

from wall paneling to furniture components, to a variety of 

utility boards for home and industry. 

This Standard was originally promulgated under the 

procedures of the U.S. Department of Commerce National 

Bureau of Standards and designated as Voluntary Product 

Standard PS 58-73. The 1982 revision was published with 

adjustments to physical properties listed in Table I which 

reflected the state of the art. In 1988 the Standard was 

reaffirmed without change . The 1995 revision made editorial 

corrections and added metric equivalents. This 2004 revision 

makes only editorial changes. 

The development of this American l\Jational Standard for Basic 

Hardboard offers manufacturers, consumers, and the general 

public concerned with the product an effective quid e 

developed under the consensus procedures of the American 

National Standards Institute. 

Consensus for this standard was achieved by use of a canvass body and 

ANSI's Essential Requirernents for due process. The following organizations, 

recognized as having an interest in hardboard standards, were contacted 

prior to the approval of this standard. Inclusion in this list does not 

necessarily imply that the organization concurred with the subm ittal of the 

proposed standard to ANSI. 

AFCO Industries Inc.	 Masonite International Corporation 

AKZO Nobel Coatings, Inc.	 Institute for Building Technology and 

CraftMaster Manufacturing, Inc.	 Safety 

Georgia-Pacific Corporation	 Stimson Lumber 

ICC Evaluation Services, Inc.	 Stork - Twin City Testing Corp. 

Jeld-Wen R&D	 Temple-Inland 

Kitchen Cabinet	 Manufacturers Assn. USDA Forest Products Laboratory 

Louisiana-Pacific Corporation	 University of Illinois 

Manufactured Housing Institute 

2 
ANSI A135.4-2004 Basic Hardboard 

1. SCOPE 

This Standard covers requirements 

and methods of testing for the 

water resistance, modulus of 

rupture, tensile strength, surface 

finish, dimensions, squareness, 

edge straightness, and moisture 

content of five classes of basic 

hardboard . Hardboard siding and 

prefinished hardboard paneling are 

covered by separate American 

National Standards. Methods of 

identifying hardboard that 

conforms to this Standard are 

provided. 

2. DEFINITION 

2.1. Basic Hardboard. 

Hardboard is a panel manufactured 

primarily from i nt e r - f e lt ed 

lignocellulosic fibers which are 

consolidated under heat and 

pressure in a hot-press to a density 

of 500 kg/m3 (31 lbs/ft' ) or 

greater. Other materials may be 

added to improve certain 

properties, such as stiffness, 

hardness, finishing properties, 

resistance to abrasion and 

moisture, as well as to increase 

strength, durability, and utility. 

2.2. Surface. Hardboard panels 

are available with either one (SlS) 

or two (S2S) smooth sides. 

3. REQUIREMENTS 

3.1. General. All hardboard 

represented as complying with this 

Standard shall meet all of the 

requirements specified herein. The 

inspection and test procedures 

contained in this section are to be 

used to determine the conformance 

of products to the requirements of 

this Standard. 

3.2. Classes. The hardboard shall 

be classified based on the physical 

properties shown in Table 1. The 

properties shall be determined in 

accordance with the applicable test 

methods in Part B of the American 

Society for Testing and Materials 

(ASTM) D 1037-99 Test Methods 

for Evaluating the Properties of 

Wood- Base Fiber and Particle 

Panel Materials, except that, when 

testing modulus of rupture, 

specimens greater than 9.5 mm 

(3/8 inch) thick shall be tested 

according to Part A, Section 14 of 

this reference. 

3.3. Surface Finish. The smooth 

surfaces shall be as free from 

visible variations in the surface 

plane as commercially practicable 

when visually inspected by an 

individual competent in the field 

3.4. Dimensions and Tolerances. The hardboard panels shall 

have a nominal width of 1220 mm 

or 1524 mm (4 feet or 5 feet). The 

nominal length of the panels shall 

be as agreed upon by the 

purchaser and the seller. The 

tolerance on the nominal width and 

length shall be plus or minus 1.6 

mrn/rn (1/64 inch/linear foot). The 

nominal thicknesses shall be as 

designated in Table 2. Thickness 

ranges shall be as specified in 

Table 2 when measured in 

accordance with the appl icable test 

method in Part B of ASTM D 1037­

99. 

3
 
ANSI A135.4-2004 Basic Hardboard 

3.5. Squareness. The length of 

the diagonals of the hardboard 

panels shall not vary by more than 

1.6 rnrn/rn (1/64 inch/foot) of 

length of the panels. Opposite 

sides of the panels shall not vary in 

length more than 3.2 mm (1/8 

inch). 

3.6. Edge Straightness. The 

edges of the hardboard panels 

shall be straight within 1.6 rnrn/rn 

(1/64 inch/foot) of length or width. 

Edge straightness shall be 

determined by stretching a string 

or w ire from one corner and 

measuring the widest distance 

between the string or wire and the 

panel edge being tested. 

3.7. Moisture Content. The 

moisture content of the hardboard 

shall be not less than 2 percent nor 

more than 9 percent and, within 

anyone shipment, shall not vary 

by more than 3 percent age points 

as measured by the moisture 

content of the modulus of rupture 

specimens. Moisture content shall 

be determined in accordance with 

the applicable test method in Part 

B of ASTM D 1037-99. Since 

hardboard is a wood-base material, 

its moisture content will vary with 

environmental humidity cond itions. 

When the humidity conditions in 

the area of intended use are a 

critical factor, the purchaser should 

specify a moistu re content ra nge 

more restrictive tha n 2 to 9 per 

cent so that fluctuation in the 

moisture content of the panel will 

be kept to a minimum. 

3.8. Marking and Identification. 

All basic hardboard which is 

represented as conforming to this 

Standard shall be identified by 

either of the following methods 

when requested by the purchaser: 

(a) Each board shall be marked 

with a colored vertical stripe or 

stripes which indicates the class of 

the board. The marking for the 

different classes shall be as 

follows: 

Number and 

Class color of stripes 

Tempered 1 Red 

Service Tempered 2 Red 

Standard 1 Green 

Serv ice 2 Green 

Industrialite 1 Blu e 

The stripe or stripes shall be 

applied to the four edges of a 

board as follows: 

On the short sides of the board, 

the stripe should be appl ied 75 mm 

(3 inches) from the left hand 

corner (as determined when the 

marker faces the side being 

marked); on the long sides of the 

board , the stripe should be applied 

75 mm (3 inches) from the right 

hand corner as determined when 

the marker faces the side being 

marked. See Figure 1 for an 

example of the placement of the 

markings. Stripes shall be 13 mm 

(1/2 inch) in width. When two 

stri pes are used they sha II be 

25mm (1 inch) apart. 

4
 
ANSI A135.4-2004 Basic Hardboard 

Figure 1. A stack of hardboard 

showing placement of markings. 

(b) The shipment or order shall be 

accompanied by a written 

certification stating the class of the 

hardboard and that the hardboard 

conforms to the requirements of 

this Standard . 

5 
ANSI A135.4-2004 Basic Hardboard 

Table 1
 

Classification of Hardboard by Thickness and Physical Properties
 

Class 

1 

Tempered 

2 

Standard 

3 

Service-Tempered 

4 

Service 

5 

Industrial ite 

Nom inal
 

thic kness
 

mm inch 

2.1 1/12 

2.5 1/ 10 

3. 2 1/ 8 

4 .8 3/1 6 

6.4 1/4 

7.9 5/ 16 

9.5 3/8 

2. 1 1/12 

2.5 1/10 

3.2 1/ 8 

4 .8 3/16 

6.4 1/4 

7.9 5/16 

9.5 3/ 8 

3.2 1/ 8 

4 .8 3/ 16 

6.4 1/4 

9.5 3/8 

3.2 1/8 

4.8 3/16 

6.4 1/4 

9.5 3/8 

11.1 7/ 16 

12.7 1/2 

15 .9 5/8 

6.4 1/4 

9.5 3/8 

11.1 7/ 16 

12.7 1/2 

15.9 5/ 8 

Wat er res istan ce Tensile st rength 

(max . ave rage per pane l) Modulus of (m in. aver age per panel) 

Water 

absorption 

based on 

wei ght 

Thickness 

Swelling 

rupture 

( min . 

average per 

pan el) 

Parallel 

to sur face 

Perpend icul ar 

to surfa ce 

percent per cent MPa psi MPa psi MPa psi 

30 25 

25 20 

25 20 

25 20 41.4 6000 20 .7 3000 0.90 130 

20 15 

15 10 

10 9 

40 30 

35 25 

35 25 

35 25 31.0 45 00 15. 2 2200 0.62 90 

25 20 

20 15 

15 10 

35 30 

30 30 

30 25 31.0 4500 13. 8 2000 0.52 75 

20 15 

45 35 

40 35 

40 30 

35 25 20. 7 3000 10 .3 1500 0.34 50 

35 25 

30 20 

25 20 

50 30 

40 25 

40 25 13.8 2000 6. 9 100 0 0.17 25 

35 25 

30 20 

6 
ANSI A135.4-2004 Basic Hardboard 

Table 2 

Thickness Ranges for hardboard Panels 

Nominal Thickne ss 

mm inch 

2.1 1/12 (0.083) 

2.5 1/10 (0 .100) 

3.2 1/8 (0 .125) 

4 .8 3/16 (0 .188) 

6 .4 1/ 4 (0 .250) 

7 .9 5/16 (0.312) 

9.5 3/8 (0 .375) 

11.1 7/16 (0.438) 

12 .7 1/2 (0.500) 

15 .9 5/8 (0 .625) 

Th ickness Range
 

( min. -max .)
 

mm inch 

1. 8 - 2. 3 0 .070 - 0.090 

2.3 - 2.8 0.09 1 - 0.110 

2.9 - 3.9 0 .11 5 - 0 .155 

4 .2 - 5.2 0.1 65 - 0.205 

5.3 - 6.7 0 .210 - 0.265 

7.4 - 8.5 0.290 - 0.335 

8.9 - 10 .2 0.350 - 0 .400 

10.4 - 11.7 0.410 - 0 .460 

12.1 - 13.3 0 .475 - 0.525 

15.2 - 16.5 0.600 - 0.650 

7
 
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