MEDC 02 (1037) DTZS  
                                                                                                          ICS: 91.100.99  
 
© TBS 2021                           Third  Edition 20 21 DRAFT TANZANIA STANDARD  
 
Metal roofing tiles — Specification  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  TANZANIA BUREAU OF STANDARDS  
     
2  ©TBS 20 21 – All rights reserved  This Tanzania Standard was published under the authority of the Board of Directors of Tanzania 
Bureau of Standards on 2021 –XX – YY.  
 
 
The Tanzania Bureau of Standards (TBS) is the statutory national standards body for Tanzania 
established under the Standards Act No. 3 of 1975, amended by Act No. 1 of 1977 and revised 
by Standards Act No. 02 of 2009.  
 
 
The Mechanical Engineering Divisional Standards Committee (MEDC) under whose supervision, 
this Tanzania Standard was prepared, consists of representatives from the following 
organizations:  
 
 
*University of Dar es Salaam, College of Engineering and Technol ogy  
*National Development Corporation (NDC)  
Weights and Measures Agency (WMA)  
Tanzania Industrial Research Development Organization (TIRDO)  
*Aluminium Africa Limited  
National Institute of Transport (NIT)  
Ministry of Works  
 
 
The organizations marked with an asterisk (*) in the above list, together with the following, were 
directly represented on the Technical Committee entrusted with the preparation of this Tanzania 
Standard:  
 
 
Tanzania Automotive Technology Centre (TATC)   
National Development Corporation (NDC)  
M.M. Investiment Steel Mills Limited  
Trans Auto Parts Company Limited (TAPCO)  
Dar Es Salaam Institute of Technology (DIT)  
 
 
 
 
Tanzania Bureau of Standards  
P O Box 9524  
Dar es Salaam  
Phone: 022 2450206/2450949/2450298  
Fax: 022 2450959  
Email: info@tbs.go.tz   
 
 
 
 
ISBN  
 
 
  
 
 
 
   MEDC 02 (1037) DTZS  
 
© TBS 2021                           Third  Edition 20 21 Metal roofing tiles — Specification  
 
 
0 Foreword  
 
Metal roofing tiles are the products that are used for the roof ing construction. Currently these 
products are available at different levels of quality and performance. Therefore, in order to meet 
performance and quality that required for ensuring the public safety, health and welfare in private, 
commercial and industr ial buildings the draft standard has  been prepared . 
 
For the purpose of deciding whether a particular requirement of this standard is complied with the 
final value, observed or calculated expressing the result of a measurement or test shall be 
rounded off in accordance with TZS 4, Rounding off numerical values . 
 
This second  edition cancels and rep laces the first edition (TZS 948: 2007 ) which is technically 
revised  
 
During the preparation of this  Tanzania S tandard, assistance was derived from the following 
publications:  
 
SABS 1022:2013 , published by the South African Bureau of Standards  Metal roofing tiles  
— Specification . 
 
SANS 5146:2005 , Paints and vanishes  — Resistance to impact of paint film , published 
by the South African Bureau of Standards.  
 
 
1 Scope  
 
This specification covers requirements for metal roofing tiles (coated or uncoated) supplied in the 
form of carbon steel sheets or aluminium alloy sheets (each comprising a series of simulated tile 
units) and for trim sections (of the same materials) designe d for use in conjunction with tile units 
of the same material and of appropriate profile.  
 
2.  Normative references  
 
The following standards contain provisions which, through reference in this text, constitute 
provisions of this standard. All standards are  subject to revision and, since any reference to a 
standard is deemed to be a reference to the latest edition of that standard, parties to agreements 
based on this standard are encouraged to take steps to ensure the use of the most recent 
editions of the s tandards indicated below.    
ASTM G 153, Standard practice for operating enclosed carbon arc light apparatus for exposure 
of non -metallic materials . 
 
SANS 903, Aluminium alloy corrugated and troughed sheets . 
 
ISO 3575, Continuous hot -dip zinc -coated carbon  steel sheet of commercial and drawing 
qualities.  
 
 
ISO 4998, Continuous hot -dip zinc -coated carbon steel sheet of structural quality.  
 
SANS 5146, Paints and varnishes – Resistance to impact of paint films . 
  
4  ©TBS 20 21 – All rights reserved  ISO 7253, Paints and varnishes – Determination o f resistance to neutral salt spray (fog).  
 
ISO 9227, Corrosion tests in artificial atmospheres – Salt spray tests . 
 
ISO 9364, Continuous hot -dip aluminium/zinc -coated steel sheet of commercial, drawing and 
structural qualities . 
 
 
3. Definitions  
 
For the pu rposes of this Tanzania Standard,  the following definitions shall apply:  
 
3.1 Acceptable  
 
Acceptable to the parties concluding the purchase contract, but in relation to the requirements 
given by this Tanzania Standard.  
 
3.2 Defective  
 
A tile unit or a trim section  that fails in one or more respects to comply with the relevant 
requirements of the specification.  
 
3.3 Lot 
 
Not less than 10 and not more than 500 units, of the same type, material, dimensions, and profile, 
uncoated or having the same coating, and bearing the  same batch identification, from one 
manufacturer, submitted at any one time for inspection and testing.  
 
3.4 Tile 
 
A sheet comprising a series of simulated tile units.  
 
3.5 Unit 
 
A full tile unit, a half tile unit, a hipping capping, a ridge capping, a sidewall f lashing, or a gable 
trim section.  
 
3.6 Base metal thickness  (BMT)  
A thickness of  the steel substrate prior to any metallic coating , resin coating and paint film being 
added to the substrate . 
 
3 Materials  
 
3.7 Carbon steel sheet  
 
Carbon steel sheets shall have a  minimum  base metal  thickness  of 0.36 mm (26G) . 
 
3.8  Aluminium alloy sheets  
 
The sheets shall comply with the requirements for chemical composition, tensile strength, and 
resistance to bending of TZS 956 (see clause 2) , and shall have a nominal thickness of at  least 
0.60 mm.  
 
 
 
   MEDC 02 (1037) DTZS  
 
© TBS 2021                           Third  Edition 20 21 3.9 Coatings  
 
A coating shall be of an acceptable colour and shall have an acceptable degree of resistance to 
weathering.  
 
For carbon steel sheets, t he hot -dip zinc coating shall comply with the requirements for class Z 
275 coatings as in T ZS 1061 -ISO 4998 (see clause 2) or TZS 1059 -ISO 3575 (see clause 2) and 
the hot -dip aluminium/zinc coating shall comply with the minimum requirements for class AZ 150 
coatings as in TZS 1060 -ISO 9364 (see clause 2).  
 
4 Requirements  
 
4.7 General  
 
Tile and trim se ction units shall be of the type and material and coated or uncoated, as specified 
by the purchaser . 
 
4.8 Dimensions  
 
The dimensions of a tile or trim section unit, determined in accordance with 8.3 shall be as 
follows:  
 
a) The thickness shall be at least equal t o be minimum given in 4.1 or 4.2, as relevant.  
 
b) The actual length (see figure 1) shall not differ by more than ± 30 mm from the nominal 
value stated by the manufacturer, and the effective length (see figure 1) shall not differ by 
more than ± 3 mm from the nominal val ue stated by the manufacturer. The downturn (see 
figure 1) shall be at least 15 mm; and  
 
c) The effective width of a tile unit (see figure 1) shall not differ by more than ± 3 mm from 
the nominal val ue stated by the manufacturer. The nose (see figu re 1) shall not differ by 
more than ± 3 mm from the value stated by the manufacturer.  
 
 
 
Figure 1 — Typical view of a metal roof tile  
  
6  ©TBS 20 21 – All rights reserved  4.9 Hail resistance (all tiles)  
 
After having been tested in accordance with 8.4 a tile unit shall be acce ptably free from visible 
defects.  
 
4.10 Profile strength (all tiles)  
 
After having been tested in accordance with 8.5 a tile unit shall show no visible sign of permanent 
deflection.  
 
4.11 Impact resistance (coated tiles)  
 
After a coated tile unit has been tested in accordance with 8.6 the coating shall show no visible 
signs of loss of adhesion  
 
4.12 Flexibility of coatings (coated units)  
 
After having been tested in accordance with 8.7 a coated unit shall show no sign of flaking or loss 
of adhesion of the coating  
 
4.13 Cold wa ter resistance (coated units)  
 
After a specimen cut from a coated unit has been immersed in water in accordance with 8.8, the 
coating on the part of the specimen that was immersed shall not  
 
a) immediately after removal from the water, be wrinkled or blistere d; 
b) after a 2  h recovery period, be more than slightly affected; and  
c) after a 24  h recovery period, show any whitening or differ more than very slightly in 
appearance from the coating on the part that was not immersed.  
 
4.14 Salt fog resistance (coated tiles)  
 
After having been tested in accordance with 8.9, a tile unit shall be free from rust, blistering 
discoloration, and loss of adhesion.  
 
4.15 Accelerated weathering resistance (coated tiles)  
 
After having been tested in accordance with 8.10, a tile unit shall be fr ee from surface defects 
such as rust, blistering, loss of adhesion, chalking of the coating and discoloration.  
 
4.16   Workmanship  
 
The surfaces of a tile unit or trim section unit shall be free from defects that detract from the unit’s 
serviceability or appear ance or both.  
 
 
5 Marking  
 
Each unit shall be legibly marked with the following information:  
 
a) The manufacturer’s name or trade name or trade mark;  
b) The date of manufacture;  
c) The batch identification; and  
d) The width and thickness of the base metal.  
 
   MEDC 02 (1037) DTZS  
 
© TBS 2021                           Third  Edition 20 21 6 Sampling a nd compliance with the specification 1)   
 
7.1 Sampling  
 
The following sampling procedure shall be applied in determining whether a lot complies with the 
relevant requ irements of the specification. The sample so taken shall be deemed to represent the 
lot. 
 
From the lot draw at random the number of units given in column 2 of table 1 relative to the 
appropriate lot size given in column 1.  
 
Table 1  — Sampling  
 
1 2 
Lot size , units Sample size, units 
10 – 50 
51 – 90 
91 – 150 
151 – 280 
281 – 500 3 
5 
8 
13 
20 
 
 
7.2 Compliance with the specification  
 
The lot shall be deemed to comply with the requirements of the specification if after inspection 
and testing of the sample taken in accordance with 7.1 no defective is found  
 
 
8 Inspection and methods of test  
 
8.1 Inspectio n 
 
Inspect each tile unit or trim section unit in the sample taken in accordance with 7.1 for 
compliance with the requirements of 5.10 and section 6. 
 
8.2 Sequence of testing and test specimens  
 
Submit the tile unit or trim section units in the s ample take n in accordance with 7 .1 to the 
applicable tests given in 8.3 – 8.10 in the order in which they are given. Use the same three units 
in the relevant tests given in 8.3 – 8.10 (inclusive).  
 
8.3 Dimensions  
 
8.3.1 Length  
 
a) Tile units. Place each sample unit (in  turn) on a flat, rigid surface, with the coated side 
uppermost and the front edge of the tile overhanging the supporting surface by not more 
than 10 mm.  
 
                                                 
1 This section applies to the sampling for inspection and testing before acceptance or rejection of single 
lots(consignments) in cases where no information about the implementation of quality control or testing during 
manufacture is available to help in assessing the quality of the lot.  It is also used as the procedure for adjudicating i n 
cases of dispute.  
  
8  ©TBS 20 21 – All rights reserved  If, because of the spring of the tile, the undersides of the troughs are not all in contact 
with supp orting surface, apply sufficient pressure to the upper surface of the tile to bring 
the undersides of the troughs into full contact with the supporting su rface. Ensure that the 
application of pressure causes no deformation of the tile other than the minimu m needed 
to bring the corrugations into contact with the rigid surface.  
 
Using a rule (or other suitable means) take measurements, to the nearest 1 mm, of the 
length of each tile at three positions (i.e. along the front and back edges and along the 
longitu dinal center -line of the tile), and record the average of the three measurements as 
the length of the tile.  
 
b) Trim section units: Record as the length of each trim section unit, the average of three 
measurements taken, to the nearest 1 mm, at three suitable  positions on the unit.  
 
8.3.2  Width  
 
Using a rule (or other suitable means) measure, to the nearest 1 mm, the transverse distance 
between the upturned and down turned faces of each tile unit in the s ample drawn in accordance 
with 7.1. Take the measurements at t hree positions on the underside of the tile unit (one at each 
end and one along the transverse center -line of the tile) and record the average of the three 
measurements as the width of the tile unit.  
 
8.3.3  Thickness  
 
Over an area of approximately 50 mm2  at eac h of three positions on each sample unit (one at 
each end and one in the center) that are at least 20 mm from an end or edge of the unit, carefully 
remove, by any acceptable means, the finish coatings other than, when relevant, the galvanized 
coatings.  
 
Then, using a micrometer caliper, measure to the nearest 0.01 mm the thickness of each unit at 
the three prepared areas, and record the average of the three measurements as the thickness of 
the unit.  
 
8.4 Hail resistance  
 
8.4.1   Apparatus  
 
A suitable gun that so fires  (vertically downwards) a spherical ice missile2) that the kinetic energy 
at impact of the missile with a test specimen (supported horizontally below the gun) is 10 ± 2 J  
 
8.4.2  Test specimens  
 
Use three tile units taken (when relevant, a t random) from the sampl e (see 7 .1). Secure each tile 
unit in the recommended manner3) to two battens of nominal width 38 mm, and of thicknesses 
such that the troughs in the coated surface are horizontal.  
 
8.4.3  Procedure  
 
Position a test specimen (with the battens on a solid, non -resilient, horizontal base, e.g. a 
concrete floor) so that impact will be made on the center of the crest of a ridge in the tile unit at a 
point approximately 40 mm away from the ne arer batten, and fire the gun. After repeating the test 
on three other (similar ) points on the tile unit, inspect the coated surface (from a distance of about 
                                                 
2 A sphere of mass 195  g ± 10 g has been used in practice but this does not impose a restriction on the use of smaller or 
larger ice spheres . 
3 i.e. as recommended by the manufacturer .   MEDC 02 (1037) DTZS  
 
© TBS 2021                           Third  Edition 20 21 2 m) for unacceptable defects. Test the remaining two test specimens in the same way.  Reserve 
the test specimens for the applicable tests given in 8.5 – 8.10 (inclusive).  
 
8.5 Profile strength  
 
8.5.1  Apparatus  
 
Two parallel horizontal bearers positioned at 1 m centers, and means for applying, through a 
bearing pad of size 225 mm x 90 mm. A force of 800 N at a point midway between the bearers.  
 
8.5.2  Test specimens (see 7.4.2)  
 
8.5.3  Procedure  
 
Position a test specimen on, and at right angles to, the bearers so that the force will be applied to 
the centers of two crests of ridges on the tile unit, at a point midway between supporting battens.  
Centre the bearing pad on this point, with the 22 mm edges  spanning two ridges, and apply, for a 
period of about 15 s, a force of 800 N, taking care to apply the load centrally and without shock.  
After removing the force, inspect (from a distance of approximately 2m) the tile unit for visible 
signs of permanent deflection.  Conduct the test on the other two specimens in a similar way.  
 
8.6 Impact resistance  
 
8.6.1  Apparatus  
 
Use the apparatus given in TZS 969:2007 . 
 
8.6.2  Test specimen  
 
From each sample unit, so cut a test specimen of size 150 mm x 70 mm that the adhesion 
betwee n the substrate and the coating is not impaired  
 
8.6.3  Procedure  
 
Place the test specimen, coated side up, flat on the base plate.  Lift the mass -piece to a height of 
640 mm (to give an impact of 5.65 J) and drop it onto the specimen. Examine the coating for 
visible signs of cracking of loss of adhesion.  
 
 
8.7 Flexibility of coatings  
 
8.7.1  Apparatus  
 
A cylindrical mandrel of nominal diameter 25 mm, rigidly supported (at convenient height) in a 
horizontal position   
 
8.7.2  Test specimen  
 
From each tile specimen or from each of th ree trim section units (as relevant) so cut a test 
specimen of suitable size that the adhesion between the substrate and the coating is not 
disturbed.  
 
 
 
 
  
10  ©TBS 20 21 – All rights reserved  8.7.3  Procedure  
 
With the coated side outwards, rapidly bend the test specimen round the mandrel through 1 80° 
(taking about 1 s for the operation), and then examine the coating for signs of flaking or loss of 
adhesion (or both).  
 
8.8 Cold water resistance  
 
8.8.1  Test specimen (As in 7.7.2)  
 
8.8.2 Procedure  
 
Immerse the test specimen for 18  h in distilled water (maintain ed at 25 ± 2°C) so that two -thirds of 
the specimen is submerged.  Inspect the specimen immediately after removal from the water, and 
again 2 h and 24 h after removal, for compl iance with the requirements of 5 .7. 
 
8.9 Salt fog resistance  
 
Using the apparatus, s alt solution, test conditions, and procedure given in TZS 968:2007 , expose, 
for a period of 1 000 h, a test specimen, of size at last 70 mm x 150 mm, cut from each tile unit 
used in 7.6, ensuring that the impact point is within the borders of the test spec imen, then 
examine the coating on each specimen for defects (see 5 .8). 
 
8.10   Accelerated weathering resistance  
 
Using the apparatus and procedure given in TZS 967 (see clause 2) , weather, for a period of 2 
000 h, the same test specimens as used in 8.9. Then e xamine the coating on each specimen for 
defects (see 5 .9). 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
   MEDC 02 (1037) DTZS  
 
© TBS 2021                           Third  Edition 20 21 Annex  A 
 
Notes to purchasers  
 
 
A.1 Tender requirements  
 
The following requirements must be specified in tender invitations and in each order or contract:  
 
a) The type of unit;  
b) The material (i.e. galva nized steel or aluminium alloy);  and  
c) Whether the units are to be coated or uncoated (see 5.1). 
 
A.2 Precautions   
 
The following precautions are to be taken at points of contact between aluminium alloy units and 
other building mate rials: 
 
a) Cement co ncrete, mortars, and plasters. Units should be insulated from contact with 
these materials by painting the contact surfaces with two coats of bituminous aluminium 
paint or zinc chromate or barium chromate primer.  
 
b) Masonry. Where practicabl e, untis should not be in contact with masonry because of the 
danger that corrosion may occur, particularly if the masonry contains chlorides or acid or 
alkaline compounds. If contact with masonry is unavoidable, the contact surfaces should 
be painted with  two co ats of bituminous aluminium paint or zinc chromate or barium 
chromate primer.  
 
c) Timber. The use of timber that has been preservative -treated with a copper or mercury 
compound in contact with aluminium al loy units, is not recommended. Timber 
preservat ives that are more compatible with aluminium (e.g. creosote or 
pentachlorophenol) should be used in preference, and the timber surfaces in contact with 
the units, should, in any case, be sealed with a bituminous aluminium or zinc chromate or 
barium chromat e coating.  
 
d) Steelwork. All steel surfaces in contact with the aluminium alloy units should be painted 
with a bituminous aluminium, zinc chromate, or other paint that does not contain lead.  In 
severe atmospheric conditions (e.g. in marine or industrial env ironments) it is advisable 
to provide additional insulation in the form of chromate -impregnated or plastic tape or 
sheeting applied to the painted surface of the steelwork before the aluminium alloy units 
are fixed.  
 
e) Lead. The use of lead washers, flashing s, etc. in contact with aluminium alloy units is not 
recommended.  Separate the contact surfaces with bituminous aluminium paint or other 
insulating material.  
 
f) The use of lead -based paints on the units or on materials in contact with it should be 
avoided.  
 
g) Zinc. Aluminium is not corroded by contact with zinc, but in severe atmospheric 
conditio ns the zinc may suffer attack. Contact surfaces between the units and zinc should 
be separated by a coating of a bituminous aluminium or of a zinc chromate or barium 
chromate primer.  
  
12  ©TBS 20 21 – All rights reserved  h) Copper and copper alloys. Copper fastenings should under no circumstances be used to 
fix aluminium alloy units.  
 
Contact between copper and aluminium results, in the presence of moisture, in very rap id 
corrosion of the aluminium. Even wate r running off copper should not be allowed to fall on or run 
over aluminium. Bare copper wire should not be suspended over aluminium roofing, and copper 
lightning conductors should not be erected on or over aluminium alloy roofs. Both finials and 
conductor s should be of al uminium or an aluminium alloy. When they are clear of aluminium alloy 
units, the aluminium conductors may be connected to the final part of the earthing conductor, 
which may be of copper, provided that the joint is completely sealed by sui table means against 
the entry of moisture.  
 
A.3 Earthing  
 
Earthing of aluminium roofs is best achieved by bolting flat aluminium conductors to the 
underside of the eaves, the final earth connection being made as described in A.2(g).  
 
A.4 Coastal areas  
 
Before using metal roofing tiles in coastal areas,  it is recommended that the advice of the 
manufacturer be obtained on the suitability of using his tiles in such areas.  
 
 
 MEDC 2 (1037) CD2  
 
©TBS 2021  – All rights reserved