FINAL DARFT UGANDA 
STANDARD  
  FDUS  2224  
First  Edition  
2020 -mm-dd 
 
 
 Reference number  
FDUS  2224 : 2020 
© UNBS 2020   
  
Expanded polystyrene f lagstones and  semi -cylinders — 
Specifications   
 FDUS  2224 : 2020  
ii © UNBS 2020  – All rights rese rved 
 Compliance with this standard does not, of itself confer immunity from legal obligations  
A Uganda Standard does not purport to include all necessary provisions of a c ontract. Users are 
responsible for its correct application  
© UNBS 2020   
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any 
form or by any means, electronic or mechanical, including photoco pying and microfilm, without prior written 
permission from UNBS.  
Requests for permission to reproduce this document should be addressed to  
The Executive Director  
Uganda National Bureau of Standards  
P.O. Box 6329  
Kampala  
Uganda  
Tel: +256 417 333 2 50/1/2 
Fax: +256 41 4 286 123  
E-mail: info@unbs.go.ug  
Web: www.unbs.go.ug  FDUS  2224 :2020  
© UNBS 2020  – All rights reserved  iii 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ............................  iv 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Requirements for the slab and semi -cylinders  ................................ ................................ ..................  3 
4.1 Composition  ................................ ................................ ................................ ................................ ...........  3 
4.2 Finishing  ................................ ................................ ................................ ................................ .................  3 
4.3 Classification by quality class  ................................ ................................ ................................ .............  3 
4.4 Physical and mechanical properties  ................................ ................................ ................................ ... 3 
4.4.1 General  ................................ ................................ ................................ ................................ ...................  3 
4.4.2  Water absorption  ................................ ................................ ................................ ................................ ... 3 
4.5 Specifications  ................................ ................................ ................................ ................................ ........  3 
4.5.1  Geome tric requirements  ................................ ................................ ................................ .......................  3 
4.5.2  Mechanical requirements  ................................ ................................ ................................ .....................  4 
4.5.3  Physical properties  ................................ ................................ ................................ ...............................  4 
5 Quality system  ................................ ................................ ................................ ................................ ....... 4 
5.1 Tests for acceptance  ................................ ................................ ................................ .............................  4 
5.2 Test methods  ................................ ................................ ................................ ................................ .........  5 
5.2.1  Acceptance tests  ................................ ................................ ................................ ................................ ... 5 
5.2.2  Discretionary tests  ................................ ................................ ................................ ................................  5 
5.2.3  Type test  ................................ ................................ ................................ ................................ .................  5 
5.3 Geometrical properties (test methods)  ................................ ................................ ...............................  5 
5.3.1  Measurement of length, width, and thickness of the expanded polystyrene slabs  .......................  5 
5.3.2  Measurement of length, interior and exterior diameter of the expanded polystyrene semi -
cylinders  ................................ ................................ ................................ ................................ .................  6 
5.4 Physical properties (test methods)  ................................ ................................ ................................ ..... 6 
5.4.1  Test for determination of thermal conductivity  ................................ ................................ ..................  6 
5.4.2  Test for determination of water vapour ................................ ................................ ...............................  7 
6 Delivery r equirements  ................................ ................................ ................................ .........................  98 
6.1 General  ................................ ................................ ................................ ................................ .................  98 
6.2 Certification of quality compliance  ................................ ................................ ................................ ...... 9 
7 Handling, shipping and storage  ................................ ................................ ................................ ...........  9 
7.1 Handling  ................................ ................................ ................................ ................................ .................  9 
7.2 Shipping  ................................ ................................ ................................ ................................ .................  9 
7.3 Storage  ................................ ................................ ................................ ................................ .................  10 
Annex  A (normative)   ................................ ................................ ................................ ................................ ...... 11 
A.1 Acceptance inspection  ................................ ................................ ................................ .......................  11 
A.2 Sampling plans  ................................ ................................ ................................ ................................ .... 11 
Bibliography  ................................ ................................ ................................ ................................ ......................  12 
 FDUS  2224 : 2020  
iv © UNBS 2020  – All rights rese rved 
 Foreword  
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry of Trade , Industry and 
Cooperatives established under Cap 327 , of the Laws of Uganda , as amended .  UNBS is mandated to co -
ordinate the elaboration of standar ds and is  
(a) a member of International Organisation for Standardisation (ISO) and  
(b) a contact point for the WHO/FAO Codex Alimentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT  Agreement  of the World Trade Organisation (WTO).  
The wo rk of preparing Uganda Standards is carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in a given field or area and consists of key stakeholders 
including government, academia, consumer groups, private  sector and other interested parties.  
Draft Uganda Standards adopted by the Technical Committee are widely circulated to stakeholders and the 
general public for comments. The committee reviews the comments before recommending the draft standards 
for appro val and declaration as Uganda Standards by the National Standards Council.  
The committee responsible for this document is Technical Committee UNBS /TC 3, Building and construction . 
 
 FINAL DRAFT UGANDA STANDARD  FDUS  2224 : 2020  
 
© UNBS 2020  – All rights reserved  1 
 Expanded polystyrene f lagstones and semi -cylinders  — 
Specifications  
1 Scope  
This Final Draft Uganda Standard specifies requirements, sampling and test methods  for expanded 
polystyrene slabs and semi -cylinders used as thermal insulators in rooms, isothermal installations and cold -
storage plants, which work in a temperat ure range of -140 °C to 70 °C.  
2 Normative references  
The following referenced documents referred to in the text in such a way that some or all of their content 
constitutes requirements of this document. For dated references, only the edition cited applies . For undated 
references, the latest edition of the referenced document (including any amendments) applies.  
ISO 2859 -1 Sampling procedures for inspection by attributes — Introduction to the ISO 2859 series of 
standards for sampling for inspection by attrib utes 
FDUS 2225, Expanded polystyrene cap vaults and coffers — Specifications  
3 Terms and definitions  
For the purposes of this document, the following terms and definitions apply.  
ISO and IEC maintain terminological databases for use in standardization at the following addresses:  
— ISO Online browsing platform: available at http://www.iso.org/obp  
3.1  
expanded polystyrene  (EPS)  slabs 
rectangular parallelepiped  used in the thermal insulation of cold stores and other co nstructive solutions that 
require it  
 
 
FDUS  2224 : 2020  
2 © UNBS 2020  – All rights reserved  
 Key 
A Width of the slab  
e Thickness  of the slab and the semi cylinder  
L Length of the slab and the semi -cylinder  
Figure 1 — Slabs  
3.2  
expanded polystyrene  (EPS)  semi-cylinder  
element in t he form of a semi -cylinder used for the thermal insulation of pipes and accessories  
 
Key 
Di Interior diameter of the semi -cylinder  
De Exterior diameter of the semi -cylinder  
e Thickness of the slab and the semi cylinder  
Figure 2  — Semi cylinder  
3.3  
type test 
test carried out for the approval of a new product, a fundamental change of formulation, or a manufacturing 
method and whose effects cannot be predicted based on previous experience . The test is performed on t he 
product in the same state it was supplied. It is required to demonstrate the conformity of the generic product to 
a specification, but it is not required for each batch of the production.  
3.4  
discretionary t est 
test that is required to demonstrate the conformity of the product to a given specification, but that is done at 
the customer's request  
FDUS  2224: 2020 
© UNBS 2020  – All rights reserved  3 
 4 Requirements for the slab and  semi -cylinders  
4.1 Composition  
The slabs and  the semi -cylinders shall be manufactured from expanded polystyrene blocks of a 
predetermined density.  
4.2 Finishing  
The expanded polystyrene slabs and semi -cylinders used as thermal insulators shall have a thickness and a 
homogeneous structure t hroughout its surface, its edges will be cut straight and parallel. Their surfaces shall 
not show deformations.  
4.3 Classification by quality class  
The slabs and semi -cylinders used as thermal insulators are classified into five classes or grades of quality, 
according to their density, as established in Table 1.  
4.4 Physical and mechanical properties  
4.4.1  General  
The physical and mechanical properties of the expanded polystyrene used in the manufacture of slabs and 
semi -cylinders that serve as th ermal insulators are given  in Table 1.  
4.4.2  Water absorption  
The water absorption of expanded polystyrene is low. Water absorption decreases as density increases as 
shown in Table 3. Fusion is the most important factor influencing the moi sture resistance of expanded 
polystyrene. Good fusion reduces the amount of water absorption. For 9 years to 12 years of service, 
equilibrium values of 8 % - 9 % volume have been found in EPS fills below the ground water table (Van Dorp, 
1988).  
Table 1 — Physical and mechanical p roperties  
Property  Density  class  
Test method  
10 15 20 25 30 
Density range , kg/m3 9.0 - 13.4 13.5 - 17.9 18.0 - 22.4 22.5 - 26.9 ≥27 FDUS 2225  
Minimum compression strength with 
deformation at 10  %, kPa - 65 100 140 180 FDUS 2225  
Thermal conductivity in 23  °C, W/mK  - 0.037  0.035  0.034  0.034  5.4.1  
Minimum flexural strength , kPa 50 160 240 325 410 FDUS 2225  
 
4.5 Specifications  
4.5.1 Geometric requirements  
The dimensions for slabs and semi -cylinders shall be es tablished according to the project requirements and 
the permissible deviations shown in Table 2.  FDUS  2224 : 2020  
4 © UNBS 2020  – All rights reserved  
 Table 2 — Dimension tolerances  
Parameter  Tolerance  
mm 
Slab  Semi -cylinder  
Length (L)  ±5 ±5 
Width (A)  ±5 - 
Thickness (e)  ±2 ±2 
Interior diameter (Di) - ±3 
Exterior diameter (D e) - ±2 
Squareness  ±2 - 
 
4.5.2 Mechanical requirements  
They are the compressive strength with deformation at 10  % and the flexural strength. Their specifications are 
presented in Table 1 and the test methods are described in FDUS 2225 . 
 
Table 3 — Other mechanical and physical requirements  
Parameter  Density class  
15 20 25 30 35 
Cross breaking strength,  Kg/cm2, 
min. 1.4 1.6 1.8 2.2 2.6 
Water vapour , g/m2, 24 h, max . 50 40 30 20 15 
Thermal stability, %, max . 1 1 1 1 1 
Water absorption , 
% After seven  days  3.0 2.3 2.2 2.0 1.9 
After one year 5.0 4.0 3.8 3.5 3.3 
 
4.5.3 Physical properties  
Density  
The values for density range shall comply with the requirem ents in Table 1. Density is tested as established in 
FDUS 2225 . 
5 Quality system  
In order to ensure the conformity of the product with this s tandard, an effective and documented quality 
system shall be established and maintained.  
5.1 Tests for acceptance  
The limit for each specification shall be evaluated according to the requirements in Table 3.  FDUS  2224: 2020 
© UNBS 2020  – All rights reserved  5 
 Table 4 — Sampling p lans 
Parameter  Sam pling plan  
Width  
ISO 2859 -1  
Inspection by attribute  
Double sampling  
AQL 6.5  % 
Level II  Length  
Thickness  
Squareness  
Interior diameter  
Exterior diameter  
Minimum density  Tested according to FDUS  2225  and 5.4.1 of this 
standa rd. It should comply with the requirements in 
Table 1  Flexural strength  
Minimum compressive strength with 10  % deformation  
Thermal conductivity at 23 °C  
 
For the sampling plans established in Table 4and their statistical interpretation see Annex A of this standard.  
5.2 Test methods  
5.2.1 Acceptance tests  
a) Geometrical properties (according to  5.3) 
b) Minimum compression strength with 10  % deformation (according to FDUS  2225 ) 
c) Density (according to FDUS  2225 ) 
5.2.2 Discretionary tests  
Flexur al strength (according to FDUS  2225 ) 
5.2.3 Type test 
Thermal conductivity at 23 °C (according  to 5.4.1) 
5.3 Geometrical properties  (test methods ) 
5.3.1 Measurement of length, width, and thickness of the expanded polystyrene slabs  
5.3.1.1  Equipment  
Tape measure with 1  mm precision   
5.3.1.2  Method  
The slabs are placed on a flat horizontal surface.  For each dimension three measurements shall be taken. 
The average of the three measurements shall be taken in the length, width and thickness  of the slab and shall 
be in accordance with the requirements in Table 2.  FDUS  2224 : 2020  
6 © UNBS 2020  – All rights reserved  
 5.3.2 Measurement of length, interior and exterior diameter of the expanded polystyrene semi -
cylinders  
5.3.2.1 Equipment  
Tape measure with 1  mm precision  
5.3.2.2  Method  
The semi -cylinder will be placed on a flat horizontal surface. For each dimension, three measurements shall 
be taken with the tape measure. The average of those three measurements shall be taken as the final length, 
interior diameter and exterior diameter of  the semi -cylinder and they must comply with the specifications in 
Table 2.  
5.4 Physical properties  (test methods ) 
5.4.1 Test for  determination of thermal conductivity  
5.4.1.1 Equipment  
5.4.1.1.1  Thermal conductivity measurement equipment  
5.4.1.1.2  Stove with forced air circulation  
5.4.1.1.3  Tape measure with 1  mm precision  
5.4.1.1.4  Vernier calliper  with ± 0.1 mm precision  
5.4.1.2 Specimens preparation for the test  
5.4.1.2.1  Two specimens of square or circular shape, of uniform thickness, and  with their flat and parallel 
faces, are cut from the sample to be tested. The square side of the diameter of the circle will have  a value 
between 300 mm and 500 mm and the thickness will be between 20 mm and 100 mm.  
5.4.1.2.2  The maximum tolerances in the  apparent density of the samples will be , after desiccation, less by 
10 % of its nominal value and a difference in thickness of more than 5  % between the two specimens will not  
be allowed. Samples should be dried at 50 ° C ± 5 ° C in an oven with forced  air circulation at constant weight 
and should not gain weight by water absorption  during the test . 
5.4.1.3  Method  
5.4.1.3.1  The test pieces are measured and weighed after desiccation. They are placed in the test 
apparatus and suitably tigh tened in order to achieve good contact.  
5.4.1.3.2  The desired temperatures of the test are programmed, which shall be those of the use of the 
insulator, making sure that the temperature difference between the heating and cooling plate is also that of 
use. 
5.4.1.3.3  The temperature difference between the centre  and the guard ring shall be statistically null 
throughout the test and to achieve this, the electric voltage of the guard ring will b e changed manually or 
automatically. Once the steady stat e, desired temperatures and gradients are reached, the temperatures of 
the various thermocouples and the heating power of the central zone shall be m easured. At the end of the 
test, the specimen is reweighed . If the weight increas e exceeds 1  %, the test is repeated . The environment 
humidity shall be controlled.  
5.4.1.3.4  The coefficient of thermal conductivity (λ ) will be  calculated as shown below . FDUS  2224: 2020 
© UNBS 2020  – All rights reserved  7 
 
 
RVQandIVQ2
. 
  
where 
Q is amount of heat , in Watt s; 
V is tension , applied to the heating plate , in Volt s; 
I is intensity , in Ampere s; 
R is resistance , in Ohms ; 
ē is average thickness , of the two samples , in me tres; 
A is surface  area of the heating plate ; 
2 1 c c c ttt
 is the average temperature , in Degrees Celsius, of the two projecting surfaces of the two 
samples ;  
 is t the average temperature , in Degrees Celsius , of the c old surfaces of the two samples and is 
calculated as shown below ;  
 
5.4.2 Test for d etermination of water vapour  
5.4.2.1  General  
Water vapour permeance of the material is determined for a specimen 50 mm thick.  The test shall be carried 
out at a temperature of 38.0 ± 0.5 ° C with relative humidity of  90 ± 2 % on one side of the specimen and < 2 
% on the other side.  
5.4.2.2  Test specimen  
The test specimen shall be a cylinder of 50 mm ± 1 mm in height. The diameter shall be  such that the 
specimen can be pushed into the beaker used for test without undue  compression on the sides of the 
specimen. For test specimen less than 50 mm thick,  plying u p without the use of adhesive  is permissible. It is 
cut from the board by a  sharp -edged, thin hollow cylindrical steel cutter. The flat faces shall be lightly sanded  
unless they have been freshly cut by means other than a hot wire.  
5.4.2.3  Number of test specimens  
Tests shall be carried out  on five test specimens cut at random from different  portions of the sample.  
5.4.2.4  Apparatus  
5.4.2.4.1  250-ml glass beaker , of approximately 65 mm internal diameter  
5.4.2.4.2  Humidity  cabinet , maintained at 38 % ± 0.5 % and 90 % ± 2 % relative humidity  FDUS  2224 : 2020  
8 © UNBS 2020  – All rights reserved  
 5.4.2.5  Reagents  
Sealing wax; the wax compound used for sealing shall be stable and nonabsorbent  to water vapour and shall 
not be brittle at room temperature. It shall  strongly adhere to the beaker and the specimen. A suitable 
composition is a mixture  of 90 parts of microcrystalline wax, such as paraffin wax, and 10 parts of suitable  
non-reactant plasticizer, for example, polyethylene film scrap  and shredding . The melting point of the sealing 
wax shall be below 75  °C. 
5.4.2.6  Procedure  
Fill the beaker with anhydrous calcium chloride to about 6 mm below the expected  position of the underside of 
the specimen. The weight of the desiccant shall be at  least ten times the total expected take up of water 
during the test. Insert the  specimen in the beaker so that the flat surface of the test specimen remaining  
exposed to the atmosphere is in level with the tip of the beaker rim. Seal the test  specimen in position by 
runni ng the melted sealing wax around the inner rim of the  beaker ( see Fig ure below ), care being taken not to 
contaminate the exposed flat surface of  the specimen. The temperature of  the wax shall not be  too high to 
soften the specimen. Weigh  accurate ly each assembly to  1 g and place it in the humidity  cabinet. Weigh 
successively at  intervals of 24 h  and plot  cumulative weight increase against  time, until at least three points  
(excluding the point of origin) lie on a  straight line.  
 
Arrangemen t of specimen for water vapour permeance test  
5.4.2.7  Calculation  
Water Vapour Permeance (WVP) shall be calculated from the slope of the straight  line drawn as nearly as 
possible through those points on the graph which represents  a substantially constant rate of gain.   
Water Vapour Permeance , in grams per square metres, in 2 h  shall be calculated as shown below.  
 
where 
W is weight increase , in milligrams ; 
A is area, of the test specimen , in square centimetres ; 
T is time, for weight increase , in hours. FDUS  2224: 2020 
© UNBS 2020  – All rights reserved  9 
 5.4.2.8 Report  
The mean of five tests  shall be report ed as the water vapour  of the test sample material.  
6 Delivery requirements  
6.1 General  
Commercialized slabs and semi -cylinders shall be legibly  and indelibly  marked with the following data:  
 )a) manufacturer’s name and/or trade mark;  
 )b) product identification ; 
 )c) manufacturing date and batch number ; 
 )d) quality class ; and  
 )e) reference number of this Uganda standard.  
6.2 Certification of quality compliance  
The product shall be delivered with its corresponding certificate of conformity, which shall include, at least, the 
following information:  
a) name and address of the manufacture r; 
a)b) product quantity ; 
a)c) batch numb er and date of manufacture;  
a)d) nomenclature of the product ; 
a)e) classification by class ; 
a)f) conformity of the product ; 
a)g) identification of the quality inspector who evaluated the product;  
a)h) signature of the person issu ing the certificate ; and  
a)i) date of delivery . 
7 Handl ing, shipping and storage  
7.1 Handling  
Handling  shall be done in such a way as not to damage the product.  
7.2 Shipping  
7.2.1 The shipping shall be preferably in a container. Transportation can also be carried out in vehicles 
whose bed has a regul ar surface and free of obstacles or substances that can damage the product. For this 
type of transport, the load shall be placed on pallets or two suitable supports placing the slabs and semi -
cylinders horizontally in pallets that reach a maximum heig ht of 4 m  from the pavement.  FDUS  2224 : 2020  
10 © UNBS 2020  – All rights reserved  
 7.2.2 For the shipping of this product, the vehicle shall have  all the safety means, such as fire extinguisher, 
bed cover, brackets, and ropes.  
7.2.3 The product shall be secured  with ropes by tying each row of the package separately. In the upper 
part of the package , angle brackets of a resistant material shall be placed in order not to damage the product 
during the mooring.  
7.2.4 If the transportation involves long distances, or at times where the influenc e of solar rays is significant, 
the load shall be covered.  
7.3 Storage  
The slabs and semi -cylinders will be stored indoors and in rooms with good ventilation. The storage shall be 
done on pallets or wooden supports placed horizontally forming pa llets that reach up to 3.5 m. Higher storage 
heights are allowed provided that there are conditions for the lifting and handling of the product without 
causing damage that affects its quality . FDUS  2224: 2020 
© UNBS 2020  – All rights reserved  11 
 Annex  A 
(normative)  
 
Sampling   
A.1 Acceptance inspection  
The acceptance inspection shall be carried out by the manufacturer, the project designer, or any other 
authorized body.  
A.2 Sampling plans  
Inspection by attribute ; the AQL for the defects of the slab s and semi -cylinders is 6.5 %. For the inspection by 
attribute, a double sampling plan is established with a level II for  the quality class according to  ISO 2859 -1. FDUS  2224 : 2020  
12 © UNBS 2020  – All rights reserved  
 Bibliography  
[1] Europe,  EN 13163:2001/ AC: 2005 , Thermal insulation products for buildings. Factory made products 
of expanded polystyrene ( EPS). Specifications  
[2] Germany, DIN 18164: 1991 , Rigid cellular plastics insulating building materials. Polystyrene foam 
impact sound insulating materials  
[3] Russia, ROCT 12998 -85, Polystyrene Film.  Specifications  
[4] Venezuela, COVENIN 2344 - 1986 , Poliestireno expandible (EPS).  
[5] Venezuela, COVENIN 2345 - 1986 , Espumas rígidas de poliestireno expandido. Determinación de las 
propiedades de flexión  
 FDUS 2224: 2020  
© UNBS 2020  – All rights reserved  13 
 Certification marking  
Products that conform to Uganda standards may be marked with Uganda National Bureau of Standards 
(UNBS) Certification Mark shown in the figure below.  
The use of the UNBS Certification Mark is governed by the Standards Act, and the Regulations made 
thereunder. This mark can be used only by those licensed under the certification mark scheme operated by 
the Uganda National Bureau of Standards and in conjunction with the relevant Uganda Standard. The 
presence of this mark on a produ ct or in relation to a product is an assurance that the goods comply with the 
requirements of that standard under a system of supervision, control and testing in accordance with the 
certification mark scheme of the Uganda National Bureau of Standards. UNBS  marked products are 
continually checked by UNBS for conformity to that standard.  
Further particulars of the terms and conditions of licensing may be obtained from the Director, Uganda 
National Bureau of Standards.  
 
 FDUS 2224: 2020    
 
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Price based on nn pages  
© UNBS 2020 – All rights reserved