DRAFT UGANDA STANDARD  
 DUS 2668: 202 3  
First  Edition  2023 
 
 
 Reference number  
DUS 2668   
© UNBS 2023  
  
Plastic  composite  roofing tiles  and ridges  — specification  
 DUS 2668   
ii © UNBS 2023 – All rights reserved  
 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 contract. Users are 
responsib le for its correct application  
© UNBS 2022   
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The Executive Director  
Uganda National Bureau of Standards  
P.O. Box 6329  
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Uganda  
Tel: +256 41 4 333 2 50/1/2/3  
Fax: +256 41 4 286 123  
E-mail: info@unbs.go.ug  
Web: www.unbs.go.ug  DUS 2668   
© UNBS 2023 – All rights reserved  iii 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ............................  iv 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 General requirements  ................................ ................................ ................................ ...........................  2 
5 Thermal resistance and thermal conductivity  ................................ ................................ ....................  3 
6 Fire resistance  ................................ ................................ ................................ ................................ ....... 4 
7 Dimensions and tolerance  ................................ ................................ ................................ ....................  4 
7.1 Dimensions  ................................ ................................ ................................ ................................ ............  4 
7.2 Tolerances  ................................ ................................ ................................ ................................ ..............  4 
8 Compressive strength ................................ ................................ ................................ ...........................  4 
9 Water absorption  ................................ ................................ ................................ ................................ ... 4 
10 Color fastness  ................................ ................................ ................................ ................................ ........  5 
11 Sampling  ................................ ................................ ................................ ................................ ................  5 
12 Marking  ................................ ................................ ................................ ................................ ...................  5 
Annex  A (normative)  Determination of breaking load for compos ite roofing tile  ................................ ...... 6 
A.1 Test principle  ................................ ................................ ................................ ................................ .........  6 
A.2 Test specimen  ................................ ................................ ................................ ................................ ........  6 
A.3 Apparatus  ................................ ................................ ................................ ................................ ...............  6 
Annex  B (normative)  Water absorption test  ................................ ................................ ................................ ... 8 
B.1 Test specimen  ................................ ................................ ................................ ................................ ........  8 
B.2 Procedure  ................................ ................................ ................................ ................................ ...............  8 
B.3 Results  ................................ ................................ ................................ ................................ ....................  8 
Bibliography  ................................ ................................ ................................ ................................ ........................  9 
 DUS 2668   
iv © UNBS 2023 – All rights reserved  
 Foreword  
Uganda National Bureau of St andards (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 standards 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 work of preparing Uganda Standards is carried out t hrough 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 Ugan da 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 approval and declaration as Uganda Standards by the Na tional Standards Council.  
The committee responsible for this document is Technical Committee UNBS /TC ###, [name of committee] , 
Subcommittee SC ##, [name of subcommittee] . 
This second/third/… edition cancels and replaces the first/second/… edition ( US nnn-n:yyyy), which has been 
technically revised.  
US nnn consists of the following parts, under the general title Introductory element — Main element :  
  Part n: Part title  
  Part [n+1]: Part title  
  Part [n+2]: Part title  
 DUS 2668   
© UNBS 2023 – All rights reserved  v 
  
 DRAFT UGANDA STANDARD  DUS 2668: 202 3 
 
 
© UNBS 2023 – All rights reserved  1 
 
 Plastic  composite  roofing tiles  and ridges  Specification   
1 Scope   
This specification applies to plastic composite roofing tiles of plain and interlocking types. It establishes 
minimum standards for fit and finish, quality of material s used in the manufacture and for dimensional 
requi rements related to side -lap, location of fixing and sizes .  
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 4582:2017(en) , Plastics — Determination of changes in colour and variations in properties after exposure 
to glass -filtered solar radiation, natural weathering or laboratory radiation sources  
ISO 22007 -1:2017(en) , Plastics — Determination of thermal conductivity and thermal diffusivity — Part 1: 
General principles  
3 Terms and definitions  
For the purposes of this docum ent, 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.  
acceptable  
A tile that has be en found without defects after inspection and testing  
3.2.  
unacceptable  
A tile that fails in one or more respects to comply with the appropriate requirements of the specification.  
3.3.  
stated length/width  
The length/width that is the manufacturer’s e quivalent to the appropriate nominal length/nominal width 
specified in Table 1.   
2 © UNBS 2023 – All rights reserved  
 
 3.4.  
nominal size  
A size of plastic composite tile , normally expressed in terms of dimensions of length, width and thickness, 
specified for its manufacture, to which its act ual size should conform within specified deviations.  
3.5 
thermal conductivity  
the ability of a given material to conduct/transfer heat  
4 General requirements   
4.1 The tiles shall be made from suitable plastic and sand. They shall have plane rectangular fac es with 
parallel sides and shall have sharp straight edges at right angle. They shall have a fine compact and, uniform 
texture.  
4.2 The tiles shall be free from excessive winding or bowing and where necessary all external angles shall 
be right angles. The tiles shall be tested for trueness of shape.  
4.3 Winding or Bowing in the Length Dimension - The tiles shall be placed between two parallel straight 
edges running along the length (see Fig. 1) and the distance between either straight edge and the adjacent  
face of the tile at any point shall not be more than 5 mm.  
4.4 Angles Between Sides and Joining Edges - Any variation from a right angle in the angle contained by 
any side and a joining edge shall be limited so that if a builder’s steel square is placed a gainst the angle, the 
maximum distance between the inner edge of the square and the side shall not be more than 5 mm (see Fig. 
2).  DUS 2668   
 
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5 Thermal resistance and thermal conductivity  
Thermal resistance and thermal conductivity shall be based upon measurements  carried out in accordance 
with ISO 22007 -1 for thick products.  
The thermal resistance and the thermal conductivity shall be determined in accordance with ISO 22007 -1 and 
declared by the manufacturer according to the following:  
 the reference mean temperatu re shall be 10 °C;  
 the measured values shall be expressed with three significant figures;  
NOTE  Zeros on the left hand side are not counted as significant figures.  
 the thermal resistance , RD, shall always be declared. The thermal conductivity, ƛ D, shall be declared 
where possible;  
 the declared thermal resistance, RD, and the declared thermal conductivity, ƛ D, shall be given as 
limit values representing at least 90 % of the production, d etermined with a confidence level of 90 %;   
4 © UNBS 2023 – All rights reserved  
 
  the value of thermal conductivity, ƛ90/90, shall be r ounded upwards to the nearest 0. 001 W/(m·K) and 
declared as ƛ D in l evels with steps of 0. 001 W/(m·K);  
 the declared thermal resistance, RD, shall be calculated from the nominal thickness, dN, and the 
corresponding thermal conductivity, ƛ 90/90, unless measured directly. For products for which 
compress ibility is measured,  the RD shall be calculated using dL instead of dN. For the calculation of 
the declared therma l conductivity, ƛ D, related to the corresponding nominal thickness, factors for the 
thickness effect conversions are given in annex B;   
 the value of thermal resistance, R90/90, when calculated from the nominal thickness, dN, and the 
corresponding thermal conductivity, R90/90, shall be rou nded downwards to the nearest 0. 05 m2·K/W, 
and declared as RD in levels with steps of 0. 05 m2·K/W;   
 the value of R90/90, for those products for which only the thermal resistance is measured directly, 
shall be rou nded downw ards to the nearest 0. 05 m2·K/W, and declared as RD in levels with steps of 
0.05 m2·K/W   
6 Fire resistance   
The tiles should be in accordance to the requirements outline d in the building code   
7 Dimensions , tolerance  and weight  
7.1 Dimensions   
The manufact urer shall declare the dimensions of the tiles .  
7.2 Tolerances  
The length and widths can deviate from the specified values up to ±5 mm while the height can deviate from 
the specified value by ±3 mm  
7.3 Weight  
Manufacture shall declare mass per square met er with a t olerance  5 percent  
8 Breaking load  
8.1 The minimum average breaking load  of the tiles when determined in accordance with th e procedure laid 
down in Anne x A shall be 3.6 KN for tiles  and 3.8 KN  for ridges.  
8.2 The breaking load  of any individ ual tile shall not fall below the minimum average crushing strength by 
more than 20 percent .  
9 Water absorption  
The water absorption of the tiles by weight. When tested in accordance with the procedure laid down in Annex 
B shall not exceed 2 percent.   DUS 2668   
 
© UNBS 2023 – All rights reserved  5 
 
 10 Color fastness  
The tile should comply with ISO 4582   
11 Sampling   
For checking the r equirements specified in 4 to 10, 25 tiles shall be select ed at random for every 2 500 til es or 
fraction thereof in a lot  by the purchaser (or his representative). The num ber of tiles taken for tests shall be not 
less than 25 in anyone lot.   
12 Marking  
The tiles shall be permanently marked with either the name or trade mark of the manufacturer  
The following particulars relating to roofing tile made in accordance with this standard shall be indicated 
clearly on the delivery note, invoice, manufacturer’s or supplier’s certificate or brochure supplied with the 
consignment of tiles: 
a) the name, trade mark or other means of identification of the manufacturer  ; 
b) the number of this s tandard;  
c) nominal dimensions.  
  
6 © UNBS 2023 – All rights reserved  
 
 Annex  A 
(normative)  
 
Determination of breaking load for composite roofing tile  
A.1 Test principle  
Verification of the ability of the product to resist a centered load when subjected to flexion on two simple 
bearers.  
A.2 Test s pecimen  
Ten tiles shall be randomly selected each one consisting of a whole tile dried in ambient air. If the tiles have 
been subjected to humidity, they shall be dried in a laboratory atmosphere before testing (temperature +10 0C 
and +40 0C, relative humi dity less than 90 %).  
A.3 Apparatus  
A.3.1  A device that applies a load with an accuracy of 2 %, and a load increase rate of 0.05 kN/s.  
A.3.2  A system used as lower bearers, and, depending on the type of tile, either made up of rods or half -
rods, one of whi ch is articulated in order to rotate in a vertical plane and obtain as uniform a load distribution 
as possible on the sample, or for some over and under tiles by a flat plate supporting the tile.  
A.3.3  A round steel bar, fitted to the bottom of the load ap plication device.  
A.3.4  A set of hardwood shims, used for chocking the lower bearers.  
A.3.5  A hardwood or moulded plaster shim, adopted to the shape of the tile.  
A.4 Procedure  
A.4.1  Place the tile on two lower bearers in the same horizontal plane so that :  
i. the first bearer is in the position normally occupied by the batten;  
ii. the second bearer is separated from the first by a distance of 200 mm center to center  from either 
bearers . 
A.4.2  In order to ensure that the tile remains in stable position, use woode n shims of the same width as the 
upper shim to support the tile on the lower bearers, and a shim adopted to fit the shape of the upper bearer.  
A.4.3 The contoured piece of wood has a strip of rubber on the upper part in contact with the tile.  
A.4.4  The wid th of the contoured hardwood shim or moulded plaster shim shall be equal to the diameter of 
the load application bar.  
A.4.5  Place the assembly in such a position that the load application bar is parallel to the two lower bearers 
and equidistant from both.  DUS 2668   
 
© UNBS 2023 – All rights reserved  7 
 
 A.4.6  apply the load at a uniform rate 0.05 KN/s using the load application bar and record the maximum 
breaking load.  
Note  the dif ference between the bearer axis i s the mass, in grams, of the dry specimen; and  
A is the mass, in grams, of the specimen after 24 h immersion in water.  
  
8 © UNBS 2023 – All rights reserved  
 
 Annex  B 
(normative)  
 
Water absorption test  
B.1 Test specimen  
Ten tiles shall be randomly selected to form the sample size according to the lot size and used for this test.  
Ten ridges shall be randomly selected to form the samp le size according to the lot size and used for this test  
B.2 Procedure  
Dry the ten tiles (or ridges) selected in an oven at a temperature of 105 °C to 110 °C till they attain constant 
weight and then cool to ambient temperature and weigh.  
When cool, imm erse the dry specimens completely in clean water at 24 °C to 30 °C for 24 h. Remove each 
specimen, wipe off the surface water carefully with a damp cloth and weigh the specimen. Weigh the 
specimen to the nearest gram within three minutes after removing the  specimen from the tank.  
B.3 Results  
B.3.1  The percentage water absorption is given by:  
 
where,  
A is the mass, in grams, of the dry specimen; and  
B is the mass, in grams, of the specimen after 24 h immersion in water.  
B.3.2  The average percentage wa ter absorption of the ten tiles (or ridges) shall be calculated and reported 
as percentage water absorption.  DUS 2668   
 
© UNBS 2023 – All rights reserved  9 
 
 Bibliography  
[1] CD/ENG X: 2019 , Plastic Composite Roofing Tiles —Specification   
 
 DUS 2668 : 2023 
© UNBS 2023 – All rights reserved  11 
 
 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 l icensed 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 product or in relation to a product is an assurance that the goods comply w ith 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 tha t standard.  
Further particulars of the terms and conditions of licensing may be obtained from the Director, Uganda 
National Bureau of Standards.  
 
 DUS 2668 : 2023   
 
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© UNBS 2023– All rights reserved