Reference number  
RS 319: 2016  
 
© RSB 2016   
 RWANDA 
STANDARD  RS 
319 
 
Second  edition  
2018-xx-xx 
Compressed straw panels  — Specification  RS 319: 2016  
©RSB 2016 All rights reserved                  ii 
 
 In order to match with technological development and to keep continuous progress in industries, 
Standards are subject to periodic review. Users shall ascertain  that they are in possession of the latest 
edition  
 
 
 
 
 
 
 
 
 
 
© RSB 2016 
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized 
in any form or by any means, electronic or mechanical, including photocopyin g and microfilm, without 
prior written permission from R SB. 
Requests for permission to reproduce this document should be addressed to  
Rwanda Standards Board  
P.O Box 7099 Kigali -Rwanda  
Tel. +250 252 586103/ 582945/ 582946  
Fax + 250 252 583305  
E-mail: info@rbs.org.rw  
Website:  www.rsb.gov.rw   RS 319: 2016  
iii                 ©RSB 2016  All rights reserved  
 
 Contents  Page  
Foreword  ................................ ................................ ................................ ................................ ............................  vi 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Terms and definitions  ................................ ................................ ................................ ...........................  1 
3 Classification  ................................ ................................ ................................ ................................ .........  2 
3.1 Gene ral ................................ ................................ ................................ ................................ ...................  2 
3.2 Composition of core  ................................ ................................ ................................ ..............................  2 
3.3 Facings  ................................ ................................ ................................ ................................ ...................  2 
3.4 Edge profile  ................................ ................................ ................................ ................................ ............  3 
4 Physical characteristics  ................................ ................................ ................................ .......................  3 
4.1 Dimensions  ................................ ................................ ................................ ................................ ............  3 
4.2 Taper profile  ................................ ................................ ................................ ................................ ...........  4 
4.3 Squareness  ................................ ................................ ................................ ................................ ............  4 
4.4 Mass  ................................ ................................ ................................ ................................ ........................  4 
4.5 Moisture content  ................................ ................................ ................................ ................................ .... 5 
4.6 Modulus of elasticity  ................................ ................................ ................................ .............................  5 
4.7 Bending strength  ................................ ................................ ................................ ................................ ... 5 
4.8 Resistance to impact ................................ ................................ ................................ .............................  5 
4.9 Screw holding  ................................ ................................ ................................ ................................ ........  5 
4.10  Thermal conductivity  ................................ ................................ ................................ ............................  5 
4.11  Boron content  ................................ ................................ ................................ ................................ ........  5 
4.12  Dimensional changes associated with changes in relative humidity  ................................ ..............  6 
5 Marking  ................................ ................................ ................................ ................................ ...................  6 
6 Test for performance an d physical characteristics  ................................ ................................ ...........  6 
6.1 Sampling  ................................ ................................ ................................ ................................ ................  6 
6.2 Routine tests  ................................ ................................ ................................ ................................ ..........  6 
6.3 Type tests  ................................ ................................ ................................ ................................ ...............  6 
7 Use of compressed straw panels  ................................ ................................ ................................ ........  6 
Annex  A (normative)  Methods of sampling, conditioning and preparation of test specimens an d 
test pieces  ................................ ................................ ................................ ................................ ..............  8 
A.1 Sampling  ................................ ................................ ................................ ................................ ................  8 
A.2 Conditioning  ................................ ................................ ................................ ................................ ..........  8 
A.3 Preparation of test  specimens  ................................ ................................ ................................ .............  9 
Annex  B (normative)  Determination of dimensions of panels ................................ ................................ .... 10 
B.1 Determination of length and width  ................................ ................................ ................................ .... 10 
B.1.1  Principle  ................................ ................................ ................................ ................................ ...............  10 
B.1.2  Test specimens  ................................ ................................ ................................ ................................ .... 10 
B.1.3  Apparatus  ................................ ................................ ................................ ................................ .............  10 
B.1.4  Procedure  ................................ ................................ ................................ ................................ .............  10 
B.1.5  Calculation and expression of results  ................................ ................................ ..............................  10 
B.1.6  Test report  ................................ ................................ ................................ ................................ ............  10 
B.2 Determination of thickness  ................................ ................................ ................................ ................  11 
B.2.1  Principle  ................................ ................................ ................................ ................................ ...............  11 RS 319: 2016  
©RSB 2016 All rights reserved                  iv 
 
 B.2.2  Test specimens  ................................ ................................ ................................ ................................ ... 11 
B.2.3  Apparatus  ................................ ................................ ................................ ................................ ............  11 
B.2.4  Procedure  ................................ ................................ ................................ ................................ ............  11 
B.2.5  Calculation and expression of results  ................................ ................................ ..............................  11 
B.2.6  Test report  ................................ ................................ ................................ ................................ ...........  12 
Annex  C (normative)  Determination of taper profile  ................................ ................................ ...................  13 
C.1 Principle  ................................ ................................ ................................ ................................ ...............  13 
C.2 Test specimens  ................................ ................................ ................................ ................................ ... 13 
C.3 Apparatus  ................................ ................................ ................................ ................................ ............  13 
C.4 Procedure  ................................ ................................ ................................ ................................ ............  13 
C.4.1  Taper width  ................................ ................................ ................................ ................................ ..........  13 
C.4.2  Taper depth  ................................ ................................ ................................ ................................ .........  13 
C.5 Calculation and express ion of results  ................................ ................................ ..............................  14 
C.5.1  Taper width  ................................ ................................ ................................ ................................ ..........  14 
C.5.2  Taper depth  ................................ ................................ ................................ ................................ .........  14 
C.6 Test repo rt ................................ ................................ ................................ ................................ ...........  14 
Annex  D (normative)  Determination of squareness  ................................ ................................ ....................  16 
D.1 Principle  ................................ ................................ ................................ ................................ ...............  16 
D.2 Test specimens  ................................ ................................ ................................ ................................ ... 16 
D.3 Apparatus  ................................ ................................ ................................ ................................ ............  16 
D.4 Procedure  ................................ ................................ ................................ ................................ ............  16 
D.5 Expression of results  ................................ ................................ ................................ .........................  16 
D.6 Test report  ................................ ................................ ................................ ................................ ...........  16 
Annex  E (normative)  Determination of mass  ................................ ................................ ...............................  18 
E.1 Principle  ................................ ................................ ................................ ................................ ...............  18 
E.2 Test specimens  ................................ ................................ ................................ ................................ ... 18 
E.3 Apparatus  ................................ ................................ ................................ ................................ ............  18 
E.4 Procedu re ................................ ................................ ................................ ................................ ............  18 
E.5 Expression of results  ................................ ................................ ................................ .........................  18 
E.6 Test report  ................................ ................................ ................................ ................................ ...........  18 
Annex  F (normative)   Determination of moisture content  ................................ ................................ ...........  19 
F.1 Oven drying method  ................................ ................................ ................................ ...........................  19 
F.1.1  Principle  ................................ ................................ ................................ ................................ ...............  19 
F.1.2  Test specimens  ................................ ................................ ................................ ................................ ... 19 
F.1.3  Apparatus  ................................ ................................ ................................ ................................ ............  19 
F.1.4  Procedure  ................................ ................................ ................................ ................................ ............  19 
F.1.5  Calculation and expression of results  ................................ ................................ ..............................  20 
F.1.6  Test report  ................................ ................................ ................................ ................................ ...........  20 
F.2 Electronic moisture meter method  ................................ ................................ ................................ ... 20 
F.2.1  Principle  ................................ ................................ ................................ ................................ ...............  20 
F.2.2  Test specimens  ................................ ................................ ................................ ................................ ... 20 
F.2.3  Apparatus  ................................ ................................ ................................ ................................ ............  21 
F.2.4  Procedure  ................................ ................................ ................................ ................................ ............  21 
F.2.5  Expression of results  ................................ ................................ ................................ .........................  21 
F.2.6  Test report  ................................ ................................ ................................ ................................ ...........  21 
Annex  G (normative)  Determination of modulus of elasticity  ................................ ................................ .... 22 
G.1 Principle  ................................ ................................ ................................ ................................ ...............  22 
G.2 Test specimens  ................................ ................................ ................................ ................................ ... 22 
G.3 Apparatus  ................................ ................................ ................................ ................................ ............  22 
G.4 Procedure  ................................ ................................ ................................ ................................ ............  23 
G.5 Calculation and expression of results  ................................ ................................ ..............................  24 
G.6 Test report  ................................ ................................ ................................ ................................ ...........  24 RS 319: 2016  
v                 ©RSB 2016  All rights reserved  
 
 Annex  H (normative)  Determination of bending strength  ................................ ................................ ...........  25 
H.1 Principle  ................................ ................................ ................................ ................................ ...............  25 
H.2 Test specimens  ................................ ................................ ................................ ................................ .... 25 
H.3 Apparatus  ................................ ................................ ................................ ................................ .............  26 
H.4 Procedure  ................................ ................................ ................................ ................................ .............  26 
H.5 Calculation and expression of results  ................................ ................................ ..............................  26 
H.6 Test report  ................................ ................................ ................................ ................................ ............  27 
Annex  I (normative)  Determination of resistance to impact  ................................ ................................ ....... 28 
I.1 Principle  ................................ ................................ ................................ ................................ ...............  28 
I.2 Test specimen  ................................ ................................ ................................ ................................ ...... 28 
I.3 Apparatus  ................................ ................................ ................................ ................................ .............  28 
I.3.1  General  ................................ ................................ ................................ ................................ .................  28 
I.3.2  The test rig  ................................ ................................ ................................ ................................ ...........  28 
I.4 Procedure  ................................ ................................ ................................ ................................ .............  30 
I.5 Expression of results  ................................ ................................ ................................ ..........................  30 
I.6 Test report  ................................ ................................ ................................ ................................ ............  30 
Annex  J (normative)  Determination of screw holding  ................................ ................................ .................  31 
J.1 Principle  ................................ ................................ ................................ ................................ ...............  31 
J.2 Test specimens  ................................ ................................ ................................ ................................ .... 31 
J.3 Apparatus  ................................ ................................ ................................ ................................ .............  31 
J.4 Procedure  ................................ ................................ ................................ ................................ .............  31 
J.5 Expression of results  ................................ ................................ ................................ ..........................  31 
Annex  K (normative)  Determination of thermal conductivity  ................................ ................................ ..... 32 
K.1 Principle  ................................ ................................ ................................ ................................ ...............  32 
K.2 Test specimens  ................................ ................................ ................................ ................................ .... 32 
K.3 Apparatus  ................................ ................................ ................................ ................................ .............  32 
K.4 Procedure  ................................ ................................ ................................ ................................ .............  32 
K.5 Expression of results  ................................ ................................ ................................ ..........................  32 
K.6 Test report  ................................ ................................ ................................ ................................ ............  33 
Annex  L (normative)  Determination of boron content  ................................ ................................ .................  34 
L.1 Principle  ................................ ................................ ................................ ................................ ...............  34 
L.2 Test specimens  ................................ ................................ ................................ ................................ .... 34 
L.3 Apparatus  ................................ ................................ ................................ ................................ .............  34 
L.4 Procedure  ................................ ................................ ................................ ................................ .............  35 
L.5 Calculation and expression of results  ................................ ................................ ..............................  35 
L.6 Test report  ................................ ................................ ................................ ................................ ............  36 
Annex  M (normative)  Determination of dimension al changes associated with changes in relative 
humidity  ................................ ................................ ................................ ................................ ................  37 
M.1 Principle  ................................ ................................ ................................ ................................ ...............  37 
M.2 Test specimen  ................................ ................................ ................................ ................................ ...... 37 
M.3 Apparatus  ................................ ................................ ................................ ................................ .............  37 
M.4 Procedure  ................................ ................................ ................................ ................................ .............  38 
M.5 Calculation and expression of results  ................................ ................................ ..............................  38 
M.6 Test report  ................................ ................................ ................................ ................................ ............  39 
Annex  N (informative)  Guidance on the use of compressed straw building panels  ................................  40 
 RS 319: 2016  
©RSB 2016 All rights reserved                  vi 
 
 Foreword  
Rwanda Standard s are prepared  by Technical Committees and approved by R wanda Standards Board of 
(RSB) Board  of Directors in  accordance with the procedures of RSB, in compliance with Annex 3 of the 
WTO/TBT agreement on the preparation, adoption and application of standards.  
The main task of technical committees is to prepare national standards.  Final Draft Rwanda S tandards 
adopted by Technical committ ees are ratified by me mbers of RSB Board of Director s for publication and 
gazett ed as Rwanda Standards.  
RS 319  was prepared by Tech nical Committee RSB/TC 009, Building materials and civil engineering . 
In the preparation of this standard, reference was made to the following standard:  
BS 4046:1991 , Compressed straw building slabs  - Specification  
The assistance de rived from the above sou rce is hereby acknowledged with thanks.  
This second edition cancels and replaces the first edition (RS  319: 2016), clause 1 of which has been 
technically revised.  
Committee membership  
The following organizations were represented on the Technical Committee  on Building materials and civil 
engineering  (RSB/TC 009) in the preparation of this standard.  
Entreprise MUBILIGI Paul (EMP)  
Horizon Construction  
Institut d’Enseignement Sup érieur de Ruhengeri (INES -Ruhengeri)  
Integrated Polytechnic Regional College -Kigal i (IPRC Kigali)  
NPD  
RULIBA Clays Ltd  
Rwanda Housing Authority (RHA)  
Rwanda Public Procurement Authority (RPPA)  
University of Rwanda - College of Science and Technology (UR -CST)  
Rwanda Standards Board (RSB) - Secretariat  RS 319: 2016  
 Compressed straw building panels  — Specification  
1 Scope  
This Rwanda S tandard specifies requirements for compressed straw panels  when used internally  and 
externally  in buildings  for non -load bearing applications . The se include the  classification of panel  types, their 
performance characteristi cs and physical properties, test methods and markin g. 
2 Terms and definitions  
For the purposes of this standard, the follow ing terms and definitions apply . 
2.1 
compressed straw panels  
panels  consisting of natural straws compressed by heat and pressure, encas ed in and firmly bonded to  
facings of paper or other materials to form rectangular panels  
2.2 
lot 
quantity of panels  manufactured under conditions which are presumed uniform  
2.3 
test panel  
panel  required for testing or from which pieces are cut for testing  
2.4 
test piece  
piece cut from a test panel  
2.5 
test specimen  
piece cut from a test piece to comply with the dimensional requirements specified in any of the  appropriate 
tests  RS 319: 2016  
© RSB 2016 All rights reserved                  2 
 
 3 Classification  
3.1 General  
Compressed straw panels  are classified according to  the c omposition of the core, the facings used and the  
profile of the longitudinal edge.  
3.2 Composition of core  
The composition of the core shall be as follows.  
 Type A : with a  solid core formed of untreated straw.  
 Type B : with a solid core formed of straw treated  during manufacture with boron -based insecticides.  
 Type C : as A but with continuous voids formed  longitudinally centrally in th e straw core, not exceeding 23 
mm diameter, capable of accepting a conduit o f 20 mm overall diameter and as shown in Figure 1.  
 Type  D: as B but with continuous voids arranged  as described in C.  
All dimensions are in millimeters  
 
Figure 1  — Typical arrangement of longitudinal voids  
3.3 Facings  
The facings shall be of the following paper types : 
 Type a : plain: paper facings suitable for accepting direct decoration.  
 Type b : plastering: paper facings suitable for  accepting gypsum plaster skim coat . 
 Type c : shower  proof: paper facings complying with the re quirements for Class A papers.  RS 319: 2016  
3                 ©RSB 2016  All rights reserved  
 
 3.4 Edge profile  
3.4.1  The profile of the longitudinal edge sha ll be of the  following types : 
 Type 1:  Square edge.  
 Type 2 : Tapered e dge, of which the dimensions of the taper shall  be as given in Clause 6 and as shown 
in Figure 2.  
3.4.2  Here is  an example of a full classification of  a panel  type:  
Type Db(2), a boron -treated panel  with longitudinal vo ids and plastering type facings and tapered longitudinal 
edges . 
All dimensions are in millimeters  
 
Figure 2  — Profile of taper edged panels  
4 Physical characteristics  
4.1 Dimensions  
When  measured in accordance with Annex B,  the dimensions of the panel  shall be as given in Table 1. RS 319: 2016  
© RSB 2016 All rights reserved                  4 
 
  
Table 1  — Dimensions and dimensional tolerances  
Dimensions  Work size  
(mm)  Maximum 
manufacturing 
(mm)  Minimum manufacturing  
(mm)  
Length  1 800 to 3 600 in 10 mm 
increments  Work size –1.0 Work size –7.0 
Width 1 200  Work size –1.0 Work size –3.0 
Thickness  50 and 58  Work size +3.0 Work size –1.0 
Thickness variation  The thickness of the centre of the panel shall not exceed that at 100 mm from an 
edge by more than 1.5  mm. 
 
4.2 Taper profile  
When measured in acc ordance with Annex C, the tapered edges shall be within the following dimensions:  
a) depth of taper : 1.0 mm to 2.0 mm;  
b) width of taper : 60 mm to 80 m m. 
4.3 Squareness  
When measured in accordance with Annex D, the deviation shall be not more than 5 mm/m measured on  the 
1 200 mm side.  
4.4 Mass  
When weighed in accor dance with Annex E, the mass of panels  shall be as given in Table 2 . 
Table 2 — Test levels for panel  mass  
Thickness  
(mm)  Minimum mass 
(kg/m2) Maximum mass 
(kg/m2) 
50 16.5 22.5 
58 18.5 24.5 
 RS 319: 2016  
5                 ©RSB 2016  All rights reserved  
 
 4.5 Moisture content  
When determined in  accordance with one of the two methods described in Annex F, the moisture content of 
the panel  when l eaving the place of manufacture shall be within the range 10 % to 18 %.  
4.6 Modulus of elasticity  
When tested in acco rdance with Annex G, th e modulus of elasticity shall be as given in Table 3. 
Table 3 — Test levels for modulus of elasticity and bending strength  
Direction of test specimen  Minimum modulus of 
elasticity  (N/mm2) Minimum bending strength  
(N/mm2) 
Specimen cut parallel to 
longitudi nal edge of panel  200 0.70 
Specimen cut at right angles to 
longitudinal edge of panel  600 1.20 
 
4.7 Bending strength  
When tested in a ccordance with Annex H, the bending strength shall be as given in Table  3. 
4.8 Resistance to impact  
When tested in acco rdance wit h Annex I, the panel  shall not fracture or exhibit residual deflection . 
4.9 Screw holding  
When tested in accordance with Annex J, the screw holding shall be not less than 175 N.  
4.10 Thermal conductivity  
When measur ed in accordance with Annex K, the thermal conduct ivity sh all be not more than 0.108 W/(m·K).  
4.11 Boron content  
When measured in  accordance with Annex L, the mean boron content shall  be not less than 0.1 %, with a 
minimum of 0.06 %.  RS 319: 2016  
© RSB 2016 All rights reserved                  6 
 
 4.12 Dimensional changes associated  with changes in relative humidit y 
When measure d in accordance with Annex M,  the increase in length and width after reconditioning  at 85 % 
relative humidity  and 35 % relative humidity  shall be not more than 0.3 %.  
NOTE  Thickness swelling with change in relative humidity has not been included because it  is insignificant.  
5 Marking  
Each panel  shall be clearly and indelibly marked by the manufacturer  on one edge with the following 
information:  
a) the manufacturer’s name, trade mark or identification mark , and 
b) the panel  classification, e.g. type Db(2).  
c) the panel  nominal thickness  
6 Test for performance  and physical characteristics  
6.1 Sampling  
Methods of sampling, conditioning and preparation of test specimens and test pieces are given in A nnex A  
and the methods of test for the various performance and physical characte ristics are given in A nnex B  to 
Annex M . 
6.2 Routine tests  
Table 4 lists the routine tests that shall be carried out regularly during production.  
6.3 Type tests  
Table 4 lists the type tests that shall be carried out whenever a change of method of manufacture is ma de that 
may affect the performance characteristics of the product.  
7 Use of compressed straw panel s 
Annex  N gives gu idance on the use of compressed straw panel s. This includes pa rticular reference to the 
need for proper sealing of the cut edges to provide co ntinuity of the surface covering and protection from 
moisture, mould growth and insect pests.  
 RS 319: 2016  
7                 ©RSB 2016  All rights reserved  
 
 Table 4  — Summary of tests for performance and physical characteristics  
Performance/physical  
characteristics  Size of test specimen  Number of tests  Requirement  
clause reference  Test method  
Routine  Type  
Dimensional tolerances  Whole panel  1 in 20  6 4.1 Annex B 
Taper profile  Whole panel  1 in 100  6 4.2 Annex  C 
Squareness  Whole panel  1 in 100  6 4.3 Annex  D 
Mass  Whole panel  1 in 20  6 4.4 Annex  E 
Moisture conten t 50 g 1 in 100  6 4.5 Annex  F 
Moisture content  Whole panel  1 in 100  6 4.5 
Modulus of elasticity  1 200 mm  × 300 mm  1 in 300  2 4.6 Annex  G 
Bending strength  1 200 mm  × 300 mm  - 2 4.7 Annex  H 
Resistance to impact  Whole panel  - 2 4.8 Annex  I 
Screw holding  100 mm  × 100 mm  - 4 4.9 Annex  J 
Thermal conductivity  300 mm  × 300 mm  - 2 4.10 Annex  K 
Boron content  5 g to 10 g  - 6 4.11 Annex  L 
Dimensional changes  1 000 mm × 1 000 mm  - 2 4.12 Annex  M RS 319: 2016  
© RSB 2016 All rights reserved                  8 
 
 Annex  A 
(normative)  
 
Methods of sampling, conditioning and preparation o f test specimens 
and test pieces  
A.1 Sampling  
A.1.1  Samples for quality control tests during production shall be taken at random, and at a frequency as 
specified in Table 4. 
A.1.2  When a consignment (lot) is to be tested for type testing, six panel s shall be t aken at random.  
A.1.3  In order to enable all tests to be carried out on a consignment, the tests described in Annex B and 
Annex E shall be carried out first on each panel . 
A.1.3.1  Two panel s shall be taken and test specimens taken for the tests described  in Annex G and 
Annex H.  
A.1.3. 2 Two further panel s shall be taken and test specimens taken for the test described in Annex I.  
A.1.3. 3 Two remaining panel s shall be taken and test specimens taken for the test described in Annex M.  
A.1.3. 4 One test specimen s hall then be taken from each panel  for the tests described in Annex F and 
Annex L.  
A.1.3. 5 One test specimen shall be taken from four panel s for the test described in Annex J.  
A.1.3. 6 One test specimen shall be taken from two panel s for the test described in Annex L.  
A.2 Conditioning  
Unless precise cond itioning is specified, the test specimens shall be  conditioned by freely exposing them for 
at least 48 h to the atmosphere of a well-ventilated room.  
Where precise conditioning is specified, the test  specimens sh all be conditioned to constant mass in an 
atmosphere of 20 °C ± 2 °C and 65 % ± 5 %.  
NOTE  Constant mass is con sidered to be achieved when two successive weighing operations car ried out at an 
interval of 24 h do not differ by more than 0.1 % of the mass of the board or tes t piece.  RS 319: 2016  
9                 ©RSB 2016  All rights reserved  
 
 A.3 Preparation of test specimens  
Test specimens shall be whole panel s, or cut from  whole panel s. All edges shall be cleanly cut at right angles 
to the panel  surface . RS 319: 2016  
© RSB 2016 All rights reserved                  10 
 
 Annex  B 
(normative ) 
 
Determination of dimensions of panel s 
B.1 Determination of  length and width  
B.1.1  Principle  
The length and width of whole panel s are determined by measurement with a metal tape or rule . 
B.1.2  Test specimens  
The test specimens shall be whole panel s of any size supplied by the manufacturer and conditioned in 
accordance with A. 2. 
B.1.3  Apparatus  
B.1.3.1  Where the accuracy of the apparatus is specified the apparatus shall be periodically calibrated.  
B.1.3.2  Steel tapes  or rules of sufficient length to measure the greatest dimension of the test specimen 
graduated to allow a reading to a n accuracy of 1.0 mm.  
B.1.4  Procedure  
Apply the steel tape, or rule, to each edge of the panel  in turn taking three measurements of width and length, 
two measurements approximately 25 mm from each edge and one on the axis of symmetry.  
Take each measurement to th e nearest 1 mm and record the results.  
B.1.5  Calculation and expression of results  
The mean val ue of the three measurements of length and width m easurements shall be calculated and 
expressed to t he nearest 1.0 mm as the length and width of the panel . 
B.1.6  Test report  
The test rep ort shall contain the following information:  
 RS 319: 2016  
11                 ©RSB 2016  All rights reserved  
 
 a) the type of board as defined in Clause 3; 
b) the result expressed in accordance  with B.1.5; 
c) a statement th at this test was carried out in accordance with this standard . 
B.2 Determination of thickness  
B.2.1  Principle  
The thickness of panel s is determined by measuring  with a micrometer or other measuring device.  
B.2.2  Test specimens  
The test specimens shall be as specified in B.1.2. 
B.2.3  Apparatus  
B.2.3.1  Genera l 
Where the accuracy of the  apparatus is sp ecified, the apparatus shall be periodically calibrated.  
B.2.3.2  Measuring device  
Having flat and parallel  measuring surfaces  16 mm ± 1 mm diameter and able to apply a total force of 0.02 
N/mm2 to the measuring surfaces. The devic e shall be graduated to allow a reading to an ac curacy of 0.01 
mm, and shall be capable of taki ng a measurement 100 mm in from the edge of the specimen.  
B.2.4  Procedure  
B.2.4.1  Take six measure ments with the measuring device approximately 40 mm from the end of the 
panel  at the positions shown in Figure C.1. 
B.2.4.2  Measure the thickness to the nearest 0.1 mm.  
B.2.5  Calculation and expression of results  
The mean value of the six measurements shall be calculated and the panel  thickness shall be expressed to 
the nearest 0.1 mm.  
The maximum difference in thickness between the measurem ent at the centre of the panel  and the thickness 
towards the edge shall be expressed to the nearest 0.1 mm.  RS 319: 2016  
© RSB 2016 All rights reserved                  12 
 
 B.2.6  Test report  
The test report shall contain the following information:  
a) the type of board as defined in Clause 3; 
b) the result expressed in accordance wi th B.2.6;  
c) a statement that this test was carried out in accordance with this standard.  RS 319: 2016  
13                 ©RSB 2016  All rights reserved  
 
 Annex  C 
(normative)  
 
Determination of taper profile  
C.1 Principle  
The thickness of the panel s over the tapered edge is determined by measuring with a measuring device.  The 
taper wi dth is measured with a steel rule.  
C.2 Test specimens  
The test specimens shall be as specified in B.1.2.  
C.3 Apparatus  
C.3.1 Where the accuracy of the apparatus is specified, the apparatus shall be periodically calibrated.  
C.3.2  Steel rule, at least 300 mm in leng th, graduated to allow a reading to an accuracy of 1.0 mm.  
C.3.3  Measuring device, as specified in B.2.3.  
C.4 Procedure  
C.4.1  Taper width  
Determine the taper width to an accuracy of ± 2 mm by applying the steel rule to the face of the panel , parallel 
to the end of t he panel  at two positions as shown in Figure C.1.  
Measure the effective taper on both sides of the panel . 
C.4.2  Taper depth  
Determine the panel  thickness as specified in B.2.4 at two positions corresponding to the edge of the taper 
and at two positions 8 mm fro m the edge of the panel  as shown in Figure C.1.  
Measure the thickness to an accuracy of 0.1 mm and record the results.  RS 319: 2016  
© RSB 2016 All rights reserved                  14 
 
 C.5 Calculation and expression of results  
C.5.1  Taper width  
Each measurement of taper width shall be reported to an accuracy of ± 2 mm.  
C.5.2  Taper depth  
The mean value of the two measurements at each of the measuring positions shall be calculated.  
Calculate the depth of taper as half the average difference between the two mean values and express it to the 
nearest 0.1 mm.  
All dimensions are in millimeters  
 
Figure C.1 — Positions for measurements of panel  thickness and taper depth  
 
C.6 Test report  
The test report shall contain the following information:  RS 319: 2016  
15                 ©RSB 2016  All rights reserved  
 
 a) the type of board as defined in Clause 3; 
b) the result expressed in accordance with C.5.1 and C.5.2;  
c) a statemen t that this test was carried out in accordance with this standard . RS 319: 2016  
© RSB 2016 All rights reserved                  16 
 
 Annex  D 
(normative)  
 
Determination of squareness  
D.1 Principle  
Squareness is determined by applying a try square to the corners of the panel  and measuring the deviation of 
the panel  edges from the edg es of the square.  
D.2 Test specimens  
The test specimens shall be as specified in B.1.2.  
D.3 Apparatus  
D.3.1  Where the accuracy of the apparatus is specified, the apparatus shall be periodically calibrated.  
D.3.2 Try square, with arms not less than 1 m in length an d an accuracy of not less than ± 0.2 mm/m,  
allowing measurement of the deviations from 90° of the panel  edge.  
D.3.3 Steel rule, graduated in 0.5 mm divisions and accurate to 0.5 mm.  
D.4 Procedure  
Apply the try square to each corner of the panel  in turn as show n in Figure D.1. Measure the maximum linear 
deviation between the square and the edge of the panel  at a distance of 1 000 mm from the corner with a 
precision of 0.5 mm, using the steel rule.  
Express the result to the nearest 1 mm/m.  
D.5 Expression of results  
The maximum linear deviation between the square and the edge of the panel  shall be expressed to the 
nearest 0.5 mm as the squareness of the panel . The designation (+) or ( –) shall be given if the angle at the 
corner of the panel  is greater or less respectiv ely than 90°.  
D.6 Test report  
The test report shall contain the following information:  RS 319: 2016  
17                 ©RSB 2016  All rights reserved  
 
 a) the type of board as defined in Clause 3; 
b) the result expressed in accordance with D.5; 
c) a statement that this test was carried out in  accordance with this standard . 
All dimen sions are in millimeters  
 
Figure D.1  — Measurement of squareness of boards  RS 319: 2016  
© RSB 2016 All rights reserved                  18 
 
 Annex  E 
(normative)  
 
Determination of mass  
E.1 Principle  
The mass per unit area is determined by weighing and measuring the test specimen.  
E.2 Test specimens  
The test specimens shall be as descri bed in B.1.2. 
E.3 Apparatus  
E.3.1 Where the accuracy of the  apparatus is specified, the apparatus shall be  periodically calibrated.  
E.3.2  Balance, capable of determining mass to the  nearest 50 g.  
E.4 Procedure  
E.4.1  Calculate the area of the specimens using the me an length and width measurements as specified  in 
B.1.5. 
E.4.2  Weigh the test specimen to the nearest 50 g.  
E.5 Expression of results  
The mass per unit area of the test specimen shall be  expressed in kg/m2. 
E.6 Test report  
The test report shall contain the followin g information:  
a) the type of board as defined in Clause 3; 
b) the result expressed in accordance with E.5; 
c) a statement that this test was carried out in  accordance with this standard . RS 319: 2016  
19                 ©RSB 2016  All rights reserved  
 
 Annex  F 
(normative)  
 
Determination of moisture content  
F.1 Oven drying method  
F.1.1  Principle  
Moisture content is determined by measuring the  loss in mass of a test specimen dried to constant  mass at 
103 °C ± 2 °C.  
F.1.2  Test specimens  
Two test specimens weighing 50 g ± 10 g shall be cut  at random from each test panel , provided that each  test 
specimen is  at least 150 mm from the ends or  edges of the panel . 
F.1.3  Apparatus  
F.1.3.1  Where the accuracy of the  apparatus is specified, the apparatus shall be  periodically calibrated.  
F.1.3. 1.1 Balance, capable of determining mass to  the nearest 0.1 g.  
F.1.3. 1.2 Air-circulating oven, capable of  maintaining an internal temperature of 103 °C ± 2 °C. 
F.1.3. 1.3 Desiccator, containing calcium chloride or  silica gel.  
F.1.3. 1.4 Metal container, to accommodate the test  piece.  
F.1.3.2  The electronic meter shall then be reset to e nsure readings are within ± 0.5 % of the result when 
measured in accordance with F.1.  
F.1.4  Procedure  
F.1.4.1  Place each test piece in a suitable container, previously dried at 103 °C ± 2 °C to constant weight 
and allowed to cool at room temperature in a desicca tor. 
F.1.4.2  Weigh the container and test piece to an accuracy of 0.1 g.  
F.1.4.3  Dry the container and test piece in the ventilated oven at a temperature of 103 °C ± 2 °C, until the 
weight is constant to 0.1 % between two weighings made at an interval of n ot less than 1 h.  RS 319: 2016  
© RSB 2016 All rights reserved                  20 
 
 NOTE  Container and test piece should be allowed to cool at  room temperature in a desiccator before each weighing.  
F.1.5  Calculation and expression of results  
F.1.5.1  The moisture c ontent of the test specimen, ω, expressed as a percentage by mas s shall be 
calculated from the equation:  
100



MM MH
 
Where , 
MH is the mass of the container and test specimen before drying (in g);  
MO is the mass of the container and test specimen after drying to constant mass (in g).  
F.1.5.2  The result shall be expressed to the nearest 0.1 %.  
NOTE  The moisture content of a panel  or batch of panel s is equal to the mean of the moisture contents of all the 
relevant test specimens.  
F.1.6  Test report  
The test rep ort shall contain the following information:  
a) the type of bo ard as defined in Clause 3; 
b) the result expressed in accordance with F.1.5; 
c) a statement that this test was carried out in  accordance with this standard . 
F.2 Electronic moisture meter method  
F.2.1  Principle  
Moisture content  is determined by the use of an electronic mo isture meter.  
F.2.2  Test specimens  
The test specimens shall be whole panel s. RS 319: 2016  
21                 ©RSB 2016  All rights reserved  
 
 F.2.3  Apparatus  
F.2.3.1  Where the accuracy of the  apparatus is s pecified the apparatus shall be periodically calibrated.  
F.2.3.2  Electronic moisture meter, capable of  measuring moisture conte nts in the range of 12 %  to 20 % 
with probes between 20 mm and 40 mm  long. The meter shall be calibrated by taking 10  readings in panel s 
covering the moisture content  range of 10 % to 18 %, and by comparing the results  with results of moisture 
content test s carried out in  accordance with F.1 on the same portions of the  panel s. 
F.2.4  Procedure  
Take six readings from each test specimen.  
F.2.5  Expression of results  
The mean moisture content shall be expressed as a percentage.  
F.2.6  Test report  
The test report shall contain the following  information:  
a) the type of board as defined in Clause 3; 
b) the result expressed in accordance with F.2.5;  
c) a statement that this test was carried out in accordance with this standard.  RS 319: 2016  
© RSB 2016 All rights reserved                  22 
 
 Annex  G 
(normative)  
 
Determination of modulus of elasticity  
G.1 Principle  
The modulus of elasticity perpendicular to the plane in bending is determined by applying a uniform line load 
at the centre of a test specimen spanning between two supports parallel to the line load and measuring the 
deflection of the specimen under the load a s the load is increased.  
G.2 Test specimens  
Two test specimens shall be cut from each test panel  and shall be 1 200 mm ± 10 mm long and 300 mm ± 5 
mm wide. One specimen shall be cut with the 1 200 mm dimension parallel to the longitudinal edge of the 
panel , and one specimen with the 1 200 mm dimension at right angles to the longitudinal edge of the panel . 
For panel s with longitudinal continuous voids the specimen with the 1 200 mm dimension parallel to the 
longitudinal edge of the panel  shall be cut so that a p air of voids (typically 57 mm apart) is positioned centrally 
± 10 mm of the width of 300 mm.  
G.3 Apparatus  
G.3.1  Where the accuracy of the apparatus is specified, the apparatus shall be periodically calibrated.  
G.3.2  Measuring device, as specified in B.2.3.  
G.3.3 Steel tape, as specified in B.1.3.  
G.3.4  Dial gauge, fitting centrally under the test specimen, with a measuring capacity of 50 mm, and 
capable of giving a reading to an accuracy of 0.1 mm.  
G.3.5  A test apparatus, as shown in Figure G.1, which shall co nsist of the following:  
a) two parallel cylindrical supports at least 300 mm long, spaced 1 100 mm apart, and having a diameter of 
30 mm ± 5 mm;  
b) a cylindrical loading head 300 mm long and having a diameter of 30 mm ± 5 mm, parallel to and centrally 
between th e supports, and adjustable in the vertical plane.  
 
 RS 319: 2016  
23                 ©RSB 2016  All rights reserved  
 
 All dimensions are in millimeters  
 
Figure G.1  — Test apparatus for determining the modulus of elasticity and bending strength  
G.4 Procedure  
G.4.1  Mark the mid points of each long edge of the test  specimen an d measure the width of the test  
specimen, between these points, with a steel rule to  the nearest 1.0 mm.  
G.4.2  Measure the thickness of the test specimen under  the load position at about 20 mm in from each edge  
with the measuring device and record the mean  of the two values to the nearest 0.1 mm.  
G.4.3  Support the specimen on the parallel supports as  shown in Figure G.1. 
G.4.4  Apply an increasing load at a rate of 15 mm ± 3 mm/m to  the test specimen and measure the 
deflection under  the sample to the nearest  0.1 mm at regular  increments of load. For this purpose the load 
shall be increased up to one -third of the expected  breaking load of the test specimen.  
G.4.5  Construct a load deflection curve for the data  obtained, as shown in Figure H.1. 
G.4.6  If the test  machine does not provide a continuous  load-deflection plot, at least eight data points up to 
one-third of  the expected breaking load of the specimen should be recorded  during the test and used to 
construct the best -fitting straight line  through these data  points.  
 
 RS 319: 2016  
© RSB 2016 All rights reserved                  24 
 
 G.5 Calculation and expression of results  
The modulus of elasticity perpendicular to the plane  of the board in bending, E m (in N/mm2), shall be  
calculated from the equation:  
SBTWYEm33
4
 
Where,  
Y is the span between supports (in mm);  
ΔW is the increment in load on the straight line position of the load -deflection curve (see Figure  G.1) (in 
N); 
B is the width of the specimen (in mm);  
T is the thickness of the specimen (in mm);  
ΔS is the increment in deflection corresponding to W increment in  load (in mm).  
G.6 Test report  
The test report shall contain the following information:  
a) the type of board as defined in Clause 3; 
b) the result expressed in accordance with G.5;  
c) a statement that this test was carried out in accordance with this standard.  RS 319: 2016  
25                 ©RSB 2016  All rights reserved  
 
 Annex  H 
(normat ive) 
 
Determination of bending strength  
H.1 Principle  
The bending strength perpendicular to the plane in bending is determined by applying a uniform distributed 
line load at the centre of a test specimen spanning between two supports. The load is increased unt il failure.  
 
 
Figure H.1 — Load deflection curve for determining the modulus of elasticity  
H.2 Test specimens  
These shall be as described in G.2. RS 319: 2016  
© RSB 2016 All rights reserved                  26 
 
 H.3 Apparatus  
H.3.1  Where the accuracy of the  apparatus is specified, the apparatus shall be  periodically calibrated.  
H.3.2  Measuring device, as specified in B.2.3. 
H.3.3  Steel tape, as specified in B.1.3. 
H.3.4  Test apparatus, as specified in G.3.4. 
H.4 Procedure  
H.4.1  Determine the width and thickness of the test  specimen as specified in G.4. 
H.4.2 Support the specimen as s pecified in G.4 and  shown in Figure G.1. 
H.4.3 Apply an increasing load through the loading head  to the specimen until fracturing of the specimen  
occurs. The rate of increase in load shall be at a rate  of 15 mm ± 3 mm/min.  
H.4.4 Record the failing load in newtons to the  nearest 5 N or 1 %, whichever is the greater.  
H.5 Calculation and expression of results  
H.5.1  The bending strength p, in (N/mm2), is given by the equation:  
223
BTWYp
 
Where,  
W is the failure load (in N);  
Y is the span between support s (in mm);  
B is the width of the test specimen (in m);  
T is the thickness of the test specimen (in mm).  
H.5.2 The bending strength of each test  specimen shall be expressed to the nearest 1 N/mm2. 
H.5.3  Bending strength may be determined on test specimens used to determine modulus of elasticity.  RS 319: 2016  
27                 ©RSB 2016  All rights reserved  
 
 H.6 Test report  
The test rep ort shall contain the following information:  
a) the type of board as defined in Clause 3; 
b) the result expressed in accordance with H.5; 
c) a statement th at this test was carried out in accordance wit h this standard . RS 319: 2016  
© RSB 2016 All rights reserved                  28 
 
 Annex  I 
(normative)  
 
Determination of resistance to impact  
I.1 Principle  
Impact strength is d etermined by allowing a body of defined mass and s hape to impact against a firmly 
supported vertical panel . 
I.2 Test specimen  
The test specimens shall be as spec ified in B.1.2. 
I.3 Apparatus  
I.3.1 General  
The apparatus shall be periodically calibrated  for the purpose of  the accuracy . 
I.3.2 The test rig  
The test rig shown in annex I.1 shall be used.  The impact pad with backing plate C and swing arm E shall 
weigh a total of 6.8 kg . 
 
 
 
 
 
 
 
 RS 319: 2016  
29                 ©RSB 2016  All rights reserved  
 
 All dimensions are in millimetres  
 
Key 
A Swivel bearing pads 50 sq: with 25 thick sponge rubber as in D 
B Pivot with stops  
C Impact pad with backing plate  
D 25 thick sponge rubber pad on a steel former, having 12 rise over 150  
E Arm 19 conduit s crewed at each end into a pivot and impact pad  RS 319: 2016  
© RSB 2016 All rights reserved                  30 
 
 Figure I.1 — Impact strength test rig  
I.4 Procedure  
I.4.1 Erect the panel  vertically an d hold rigid at head and base. The test rig sh all be rested against the 
panel , and restrained durin g the test just sufficientl y to keep the swivel b earing pads in contact with the panel.  
I.4.2 Allow the impa ct pad to fall freely from rest as near as practicable t hrough 180°.  
I.4.3 Deliver a single blow at a po int approximately 1 200 mm from ground level  and midway in the width of  
the test panel . 
I.4.4 After delivery of the single impact , catch the swing  arm to prevent any further impact.  
I.5 Expression of results  
Failure or otherwise of the specimen shall be recorded.  
NOTE  Failure occurs if the surface of the panel  fractures or exhibi ts residual deflection.  
I.6 Test report  
The test report shall contain the following information:  
a) the type of board as defined in Clause 3; 
b) the result expressed in accordance with I.5;  
c) a statement that this test was carried out in accordance with this standard.  RS 319: 2016  
31                 ©RSB 2016  All rights reserved  
 
 Annex  J 
(normative)  
 
Determination of screw holding  
J.1 Principle  
Face screw holding is determined by measuring the axial force required to withdraw a wood screw from the 
test specimen.  
J.2 Test specimens  
Test specimens 100 mm ± 5 m × 100  mm ± 5 mm shall be cut from tes t panel s as specified in A.1 and  
conditioned as specified in A.2.  
J.3 Apparatus  
J.3.1  The apparatus shall be periodically calibrated  for the purpose of the accuracy . 
J.3.2  Test machine, capable of applying an  increasing axial loa d to the underside of the screw  head 
through a suitable stirrup whilst adequately  restraining the test specimen.  
J.3.3 Steel  countersunk wood screws, 38 mm long by no. 10  screw gauge  
J.4 Procedure  
Screw one 38 mm wood screw into the centre of a  face of each specim en and perpendicular to it  to a depth of 
35 mm ± 2 mm.  Support the test specimen in such a way that the  surface of the specimen is not supported at 
any point closer than 25 mm to the axis of the screw a nd is held perpendicular to the direction of the force 
applied to the screw.  
Apply an increasing a xial tensile force to the screw head at a constant r ate so that complete pullout of the 
screw occurs between 30 s and 120 s.  
J.5 Expression of results  
The maximum load sustained by the test specimen  shall, be expressed to the nearest newton.  RS 319: 2016  
© RSB 2016 All rights reserved                  32 
 
 Annex  K 
(normative)  
 
Determination of thermal conductivity  
K.1 Principle  
The therm al conductivity is determined using appropriate methods.  
K.2 Test specimens  
The test specimens shall be conditioned and shall  be 300 mm × 300 mm and of 50 mm or 58 mm  thickness. 
The cut edg es shall be sealed with  self-adhesive tape which shall not overlap the faces  of the panel . 
K.3 Apparatus  
K.3.1  Where the accuracy of the  apparatus is specified, the apparatus shall be  periodically calibrated.  
K.3.2 Guarded hot plate, with hot and cold plates capable of b eing maintained at temperatures of 30 °C and 
15 °C respectively . 
K.3.3 Apparatus for the determination of  moisture content as specified in F.1.3. 
K.4 Procedure  
K.4.1  Use a composite tes t specimen formed from two test specimens on either s ide of the guarded hot 
plate and determine the thermal conductivity.  
K.4.2 Weigh the test specim ens to an accuracy of 0.01 g as soon as the thermal conductivity test is 
concluded.  
K.4.3 Dry the test specimens to constant mass as specified  in F.1.4. 
K.5 Expression of resu lts 
The thermal con ductivity shall be expressed in W/(m·K). The moistur e content results shall also be expressed 
for the same test specimen as specified in F.1.5. RS 319: 2016  
33                 ©RSB 2016  All rights reserved  
 
 K.6 Test report  
The test report shall contain the following  information:  
a) the type of board as def ined in Clause 3; 
b) the result expressed in accordance with K.5; 
c) a statement that this test was carried out in  accordance with this standard.  RS 319: 2016  
© RSB 2016 All rights reserved                  34 
 
 Annex  L 
(normative)  
 
Determination of boron content  
L.1 Principle  
A test specimen is broken into small lengths of straw and ex tracted  with a known volume of boiling water. The 
boron content of the extract is determined by titration in the presence of mannitol.  
L.2 Test specimens  
One specimen sh all be cut from each test panel , ensuring that the specimens are evenly positioned across 
the width o f the panel s. The test specimens shall be  conditioned as specified in A .2. The  weight of each test 
specimen shall be from 5 g  to 10 g.  
L.3 Apparatus  
L.3.1  Where the accuracy of the  apparatus is sp ecified, the apparatus shall be periodically calibrate d. 
L.3.2 A 250 mL flat -bottomed flask, with ground  glass socket.  
L.3.3 Liebig conde nser, with ground glass cone to fit flask.  
L.3.4 Standard laboratory glassware  
L.3.5 Hydrochloric acid, A.R., 2.5 % (V/V).  
L.3.6 Sodium hydroxide, A.R. N/10 CO 2 free, standa rdized, c(NaOH) = 0.1 mol/L.  
L.3.7 Mannitol (neutral).  
L.3.8 Methyl red indicator, 0.1 % (m/V) solution in ethanol.  
L.3.9 Phenolphthalein indicator, 0.1 % (m/V)  solution in ethanol.  
L.3.10  Balance,  capable of determining mass to nearest 0.01 g.  RS 319: 2016  
35                 ©RSB 2016  All rights reserved  
 
 L.4 Procedure  
L.4.1 Cut the test sp ecimen into lengths up to 10 mm long. Weigh all the sp ecimen to an accuracy of 0.01 g 
into a 250 mL fla t-bottomed flask and add 125 mL of distilled water.  
L.4.2 Connect the flask to the condenser and boil the  contents gently unde r reflu x for 30 min. Remove the 
heat source and allow t he flask to cool to about 50 °C with the top of th e condenser being covered by an 
inverted small beaker.  
L.4.3 Remove approximately 25 mL of the extract by  pipette and use this  to wash down the inside of the 
condenser, returning the washings to the bulk of the extract in the flask.  Stop the flask and allow to cool to 
room temperature.  
L.4.4 Pipette a 50 mL aliquot of the extract into a conical flask and add three drops of methyl red indicator.  
L.4.5 Add the HC l solution [2.5 % (V/V)] drop  wise until the indicator turns red, adding a few drops in 
excess. Cover the flask with a watch  glass and gently simmer the solution for 2 min to remove CO 2. 
L.4.6 Cool the flask to room temperature and neutralize with standard  NaOH solution from a burette until 
the colour turns pink.  
L.4.7 Add 10 g mannitol followed by 10 drops phenolphthalein indicator and titrate with standard  NaOH 
solution until the colour turns pink. Record this titre (T1).  
L.4.8 Determine a reagent blank a nd record the titre (T2).  
L.5 Calculation and expression of results  
L.5.1  The value of boron, B, expressed as a percentage in the test specimen sample shall be calculated 
from the equation:  
10050.2 082.1

 WNTB
 
Where,  
T is the corrected titre, i.e. T1 – T2; 
N is the normality of sodium hydroxide solution;  
W is the weight of air dry straw sample.  
L.5.2  Both the mean and minimum boron content shall be expressed to the nearest 0.05 %.  RS 319: 2016  
© RSB 2016 All rights reserved                  36 
 
 L.6 Test report  
The test report shall contain the following information:  
a) the type of board as defined in Clause 3; 
b) the result expressed in accordance with L.5;  
c) a statement that this test was carried out in accordance with this standard.  RS 319: 2016  
37                 ©RSB 2016  All rights reserved  
 
 Annex  M 
(normative)  
 
Determination of dimensional changes associated with changes in 
relative humidity  
M.1 Princ iple 
The differences in length and width of the test specimens after conditioning at 20 °C and 65 % relative 
humidity followed by reconditioning at either 25 °C and 35 % r elative humidity  or 25 °C and 85° relative 
humidity are expressed as a percentage inc rease (+) or decrease ( –) of the original value.  
M.2 Test specimen  
M.2.1 One test specimen shall be cut from each panel  and shall be 1 000 mm ± 10 mm × 1 000 mm ± 10 
mm × board  thickness . All cut edges shall be resealed with 100 mm wide waterproof tape .  
M.2.2 Round metal pins of 10 mm in diameter and 65 mm  long shall be inserted and cemented into a 
predrilled  hole in one face of the specimen to a depth of 45 mm.  
M.2.3 The pins shall be positioned 100 mm in from the  edge to define the principal dimensions of le ngth and 
width which shall be approximately 800 mm.  
M.2.4 Sufficient pins shall be inserted to allow for two  measurements of length and width to be taken on  
each test specimen.  
M.3 Apparatus  
M.3.1  Where the accuracy of the  apparatus is specified, the apparatus  shall be  periodically calibrated.  
M.3.2  Measuring device, capable of measuring  dimensions to an accuracy of 0.05 min.  
M.3.3  Controlled humidity room, or airtight  vessels capable of maintaining the required relative  humidities.  
M.3.4  Calibrated hygrometer,  to measure and  record relative humidity to an accuracy of ± 2 % in  test room 
or each vessel.  
M.3.5  Balance, capable of reading up to 30 kg to  an accuracy of 0.01 kg.  RS 319: 2016  
© RSB 2016 All rights reserved                  38 
 
 M.4 Procedure  
M.4.1  Condition the test specimens  at 65 % ± 5 % relative humidity and 20 °C ± 2 °C, to constant mass as  
specified in A.1.2. Measure the length and width  between the pairs of metal pins to an accuracy  of 0.05 mm.  
M.4.2 Repeat the measurements after conditioning the  specimens to constant mass at 35 % ± 5 % relative 
humidity and 25 °C ± 2 °C, and 85 % ± 5 % relative humidity and 25 °C ± 2 °C.  
NOTE  The preliminary equilibrium measurement is made at 65 % relative humidity so that it can be seen what 
proportion of the observed dimensional changes in the 35 % to 85 % relative humidity range  takes place above or below 
this figure. 65 % relative humidity is taken to represent the average conditions to which the boards will be exposed in 
normal use.  
M.5 Calculation and expression of results  
M.5.1  The increases in length and width after  reconditioni ng to 85 % relative humidity,  IL and IW, and the  
decreases in length and width after reconditioning  to 35 % r elative humidity , DL and DW, expressed as 
percentages,  shall be calculated from the equations:  
1008001

LIL
 
1008001

WIW
 
1008002

LDL
 
1008002

WDW
 
Where , 
ΔL1 is the average difference in length at 20 °C  & 65 % r elative humidity  and 25 °C & 85 % relative 
humidity ; 
ΔW 1 is the average difference in width at 20 °C & 65 % relative humidity and 25 °C & 85 % relative 
humidity;  
ΔL2 is the average difference in length at 20 °C & 65 % relative humidity and 25 °C & 35 % relative 
humidity  
ΔW 2 is the average difference in width at 20 °C & 65 % relative humidity and 25 °C & 35 % relative 
humidity  RS 319: 2016  
39                 ©RSB 2016  All rights reserved  
 
 M.5.2 The result shall be e xpressed as a positive value (+ %) for  IL and IW and as a negative value ( –%) for 
DL and DW to the nearest 0.05 %.  
M.6 Test report  
The test report shall contain the following information:  
a) the type of board as defined in Clause 3; 
b) the result expressed in accordanc e with M.5;  
c) a statement that this test was carried out in accordance with this standard.  RS 319: 2016  
© RSB 2016 All rights reserved                  40 
 
 Annex  N 
(informative)  
 
Guidance on the use of compressed straw building panel s 
N.1 Compressed straw panel s should be stored on flat and  level ground by supporting on at least  three 
equally  spaced bearers positioned parallel to the short edges  of the panel s, with bearers at the ends of the 
panel s. 
N.2 Panel s should be well protected from rain or  dampness or accidental damage.  
N.3 As with other organic building materials,  compre ssed straw panel s should not be used in  permanently 
damp situations, or when continuous  high humidity conditions exist. The guidance of the  manufacturer should 
be sought if it is intended to  use panel s in high humidity conditions.  
N.4 The compressed straw panel s referred to in this  standard are for use in building construction for  such 
purposes as roof lining or ceilings; as  partitioning with or without framing; or as inner  lining to external walls of 
brick, metal or other  materials.  
N.5 For internal applic ations in unheated buildings, or for temporary application, panel s types A or C are 
suitable. For all other internal applications, types B or D are suitable.  
N.6 For domestic partitioning application, panel s of type D.b (2) should be used. Panel s may be fi xed 
together at the edges and erected without framing. Type (b) facings are suitable for plastering with neat board 
finish plaster, type class B (b2) to a minimum thickness of 3 mm.  
N.7 When panel s are cut, the cut edges should be adequately sealed as reco mmended by the manufacturer 
to prevent the ingress of moisture insects or mould growth. Polyvinyl Acetate ( PVA)-based liquid sealers and 
self-adhesive tapes should be used . In addition cut edges across the width of the panel  (which being cut in the 
directi on of the straw fibres tend to be looser) should be sealed with 100 mm self -adhesive tape.  
N.8 Where the panel  surface is cut to accommodate electrical services, outlet boxes should be fixed to the 
panel  in accordance with the manufacturers’ instructions.  Any exposed straw surfaces around the box or 
where the electrical cable enters the box should be effectively sealed.  
N.9 Compressed straw panel s should not be  used as self -supporting roof decking. When used for internal 
wall or roof lining, a grade of panel with a shower  proof facing, i.e. facing type (c), sh ould be used with this 
facing adjacent to the cavity between the panel  and the roof or wall.  
  
ICS 79.060.20  
 
 
©RSB 2016 All rights reserved