DRAFT UGA NDA STANDARD  
  DUS 2026  
First E dition  
2019 -04-26 
 
 
 Reference number  
DUS 2026 :2019 
© UNBS 2019   
  
Preservative -Treated  Timber  
 DUS 2026 :2019  
ii © UNBS 2019  – 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 
responsible for its correct application  
© UNBS 2019  
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 photocopying 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 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 2026 :2019 
© UNBS yyyy – All righ ts reserved  iii 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ............................  iv 
Preservative -Treated Ti mber  ................................ ................................ ................................ .............................  1 
1 Scope  ................................ ................................ ................................ ................................ ................................  1 
2 Normative References ................................ ................................ ................................ ...........................  1 
3 Terms and Definitions  ................................ ................................ ................................ ...........................  2 
4 Requirements  ................................ ................................ ................................ ................................ ...................  4 
4.1 General  ................................ ................................ ................................ ................................ ..........................  4 
4.2 Sapwood  ................................ ................................ ................................ ................................ ........................  4 
4.3 Moisture content  ................................ ................................ ................................ ................................ ...........  4 
4.3.1 Before preservative treatment  ................................ ................................ ................................ .................  4 
4.3.2 After preservative treatment  ................................ ................................ ................................ ....................  4 
4.4 Preservative  ................................ ................................ ................................ ................................ ..................  4 
4.5 Penetration of preservative  ................................ ................................ ................................ .........................  5 
4.5.1 Penetratio n of heartwood  ................................ ................................ ................................ .........................  5 
4.5.2 Penetration of sapwood  ................................ ................................ ................................ ............................  5 
4.6 Retention of preservative  ................................ ................................ ................................ ............................  5 
4.7 Water repellent  ................................ ................................ ................................ ................................ ..............  5 
5 Marking  ................................ ................................ ................................ ................................ .............................  5 
5.1 General  ................................ ................................ ................................ ................................ ..........................  5 
5.2 Position  of marking  ................................ ................................ ................................ ................................ ...... 6 
5.2.1 Stress -graded structural timber  ................................ ................................ ................................ ...............  6 
5.2.2 Laths, stakes and garden edging  ................................ ................................ ................................ ............  6 
5.2.3 General purpose poles, cylindrical rails, half -rounds, rail bearers and slabbed poles  ...................  11 
5.2.4 All other sawn timber products  ................................ ................................ ................................ .............  11 
5.3 Rules to be observed in Marking  ................................ ................................ ................................ ..............  11 
6 inspection and methods of test  ................................ ................................ ................................ ...................  12 
6.1 Test specimens  ................................ ................................ ................................ ................................ ...........  12 
6.2 Moisture content  ................................ ................................ ................................ ................................ .........  12 
6.2.2 Untreated units  ................................ ................................ ................................ ................................ ........  12 
6.2.3 Treated units  ................................ ................................ ................................ ................................ ............  12 
6.3 Penetration of preservative and presence of sapwood  ................................ ................................ ..........  12 
6.4 Retention of preservative  ................................ ................................ ................................ ..........................  12 
6.5 Determination of water repellency  ................................ ................................ ................................ ............  13 
Bibliography  ................................ ................................ ................................ ................................ ......................  16 
 DUS 2026 :2019  
iv © UNBS 2019  – All rights reserved  
 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 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 through Technical Committees. A Technical 
Committee i s 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 approval and declaration as Uganda Standards by the National Standards Council.  
The committee responsible for this document is Technical Committee UNBS /TC12, furniture.    
 
 DRAFT UGANDA STANDARD  DUS2026 : 2019  
 
© UNBS  2019  – All rights reserved  1 
 Preservative -Treated  Timber  
1 Scope  
 
This Draft Uganda S tandard sp ecifies treatment requirements for  preservative -treated timber and timber 
products  that have a  predicted service life at various level s of preservative treatment which are considered to 
be acceptable  for a range of hazard conditions.  
 
This Draft S tandard is not applicable to treatment with fire retardants or to treatments aimed at improving  the 
physical properties of timber and timber products , nor does it cover the inherent quality of timber or  timber 
products, or properties other than in resp ect of preservative treatment.  
2 Norma tive R eferences   
The following referenced documents are indispensable for the application of this document. For dat ed 
references, only the edition cited applies. For undated references, the latest edition of the referenced 
document (including any amendments) applies  
. 
DUS 1722 , Eucalyptus poles, cross -arms and spacers for power distribution and telephone sys  
 DUS 2020 Heartwood detection in timber of the Eucalyptus species  
DUS 2021, The preservative treatment of timber  
DUS 2084, Heartwood detection in timber of pinus species  
DUS 2018, Retention of preservative in timber (sample method).  
DUS 2013, Retention of preservat ive in timber (volume method)  
DUS 2019, Retention of preservative in timber (weighbridge method).  
DUS 2016, Moisture content of timber (electric moisture meter method)  
DUS 2014, Moisture content of timber and timber products (oven dry method)  
DUS 2015, Moi sture content of timber (extraction method)  
DUS 2017, Depth of penetration of preservative and detection and depth of sapwood in timber  
US EAS 323 Specification for wood preservation by means of pressure creosoting  
US EAS 324 Copper/chromium/arsenic compo sitions for the preservation of timber — Method for timber 
treatment . 
DUS 2039 , Preparation of test specimens for moisture content determination in timber and timber  products.   
2 © UNBS 2019  – All rights reserved  
 3 Terms and D efinitions   
For the purposes of this standard the definitions given  in DUS 2021  and the following definitions  
apply:  
 
3.1 
Acceptable  
Acceptable to the authority administering this standard, or to the parties concluding the purchase  contract, as 
relevant  
3.2 
Complete sapwood  
Sapwood  available in the timber for penetration  by the preservative  
3.3 
Cylindrical  rail 
a pole manufactured with a smooth finish and a uniform diameter at both ends or throughout the length  of the 
pole  
3.4 
Garden  edging  
joined or individual pieces of sawn timber of cross dimensions at least 25 mm × 75 mm, or round timber  of top 
diameter 30 mm to 100 mm and of length 200 mm to 800 mm, normally used as borders in  gardens  
3.5 
General  purpose pole  
A deb arked round pole, where no visual and strength requirements are required   
3.6 
Half round  
One of the ha lves obtained by sawing a pole longitudinally along a diameter  
3.7 
Hazard  class  
a class in a classification of the conditions of use of timber that is based on the probability of attack by  wood -
destroying organisms and is numbered from 0 to 6, in ascendin g order of probability of attack  
3.8 
Incising  
operation of puncturing the lateral surfaces of wood as an aid in securing deeper and more uniform  
penetration of preservative  
3.9 
Laths  
round timber of lengths 3,0 m to 4,5 m and top diameters 10 mm to 32 mm  
 
3.10 
Penetration  
Depth  to which preservative enters the wood  
 
3.11 
rail bearer  
A round pole, or cylindrically turned pole, with holes drilled on the face to accommodate cylindrical rails  DUS 2026 :2019  
© UNBS 2019  – All rights reserved  3 
  
3.12 
Refusal  point  
Point  beyond which the rate of absorption at m aximum permitted pressure and temperature is too slow  to be 
significant or does not exceed a specified percentage of the amount already injected when the  wood is 
subjected to refusal treatment  
 
3.13 
Refusal  treatment  
Treatment  of wood under specified cond itions until quantity of preservatives absorbed in a given time is  not 
more than a prescribed percentage of the amount already injected  
 
NOTE  Treatment to refusal does not however, constitute an acceptable alternative to the minimum penetration or  retenti on 
requirements or both specified under the results of treatment except as specifically listed.  
 
3.14 
Retention  by assay  
Determination  of preservative retention in a specified zone of treated wood by extraction or analysis of  specific 
samples such as (a) increment borer cores or (b) chips obtained with a wood bit  
 
NOTE The method applies to freshly treated and to old material, and to larger samples if necessary .  
 
3.15 
slabbed pole  
A pole that has been so machined that it has one or more flat faces that r un parallel to the longitudinal  axis of 
the pole along the entire length of the  pole  
3.16 
Solid  penetration  
Presence  of preservative (where relevant, as indicated by an acceptable chemical test) in all or in a  specified 
portion (as relevant) of the sapwoo d, to an e xtent that causes complete color ation  of that area  of the sapwood  
 
3.17 
Stake  
Sawn  timber of maximum cross dimensions 38 mm × 38 mm or round timber that has a top diameter not  
exceeding 50 mm, intended for use as supports in agricultural applica tions such as tomato, and banana  
stakes  
 
3.18 
Timber  
Sawn  or otherwise processed wooden products, other than composite board products and timber  products   
 
  
4 © UNBS 2019  – All rights reserved  
 4 Requirements  
 
4.1 General  
Preservative -treated timber shall have been treated in accordance wit h DUS 2039  
4.2 Sapwood  
The minimum amount of sapwood present, determined in accordance with 6.3, shall be such as to  achieve the 
minimum average net retention as specified in column 6 of tables 1, 2 or 3.  
 
4.3 Moisture content  
4.3.1 Before preservative tre atment  
Immediately before the preservative treatment of timber, the average moisture content of the timber,  
determined in accordance with 6.2, shall not exceed the appropriate maximum value recommended in  DUS 
2039 , except for the following specified round timber products, i.e. general purpose poles, laths,  garden 
edging, half -rounds, cylindrical rails, rail bearers, slabbed poles and stakes, which shall not,  before 
preservative treatment, exceed the following:  
 
a) if the units are to be treated with a class  W, type WCCA preservative: 300 g/kg;  
b) if the units are to be treated with a class C preservative: 300 g/kg;  
c) if the units are to be treated with a class O preservative: 250 g/kg; and  
d) if the units are to be treated with a class W, type WB preservati ve, 
1) by using the diffusion or pressure process: no limitation; or  
2) by using the gas -phase process: 100 g/kg.  
 
NOTE The wetting of a piece of timber during treatment with a class W preservative reduces the strength  properties of the 
timber. The normal working stresses assigned to a specific grade are, however, not affected,  although the use of wet 
timber in a load -bearing application can, because of creep, lead to excessive deflection.  
 
4.3.2 After preservative treatment  
The average moisture content of timber treated with a class C or class O preservative, determined in  
accordance with 6.2 shall not exceed the appropriate maximum value recommended in SANS 10005,  except 
for the round timber products specified in 4.3.1, which shall not exceed the value giv en in 4.3.1(b)  and 
4.3.1(c).  
 
4.4 Preservative  
The type of preservative used shall be one of those given in column 5 of tables 1, 2 or 3, as required  (see 
A.1), appropriate to the hazard class and the end use (see columns 1 and 4).  Single -purpose preservat ives 
(insecticides) are catered for in hazard class H0 -i and H0 -it. 
 
 
 
 DUS 2026 :2019  
© UNBS 2019  – All rights reserved  5 
 4.5 Penetration of preservative  
4.5.1 Penetration of heartwood  
When determined in accordance with 6.3, the depth of penetration of preservative into heartwood that  appears 
on the surfa ce of preservative -treated timber, including that exposed by checks and splits,  unless otherwise 
required (see A.1), shall be at least 0,5 mm.  
 
NOTE Deeper penetration of heartwood should be specified only if based on the known penetrability of the timber  in 
question.  
 
4.5.2 Penetration of sapwood  
When determined in accordance with 6.3, the depth of penetration of preservative into sapwood that  appears 
on the surface of preservative -treated timber shall be as given in column 7 of tables 1, 2 or 3.  
4.6 Reten tion of preservative  
The average net retention of preservative in each charge of a lot of preservative -treated timber,  determined in 
accordance with 6.4, shall comply with the appropriate values given in column 6 of  tables 1, 2 or 3.  
 
4.7 Water repellent  
When so required (see A.1), an acceptable water repellent shall be added to a class W or class O  
preservative (see DUS 2021 ). When timber treated with the water -repellent preservative is tested in  
accordance with 6.5, the short -term repellency shall be at l east 60 %.  
 
NOTE  Because of the variable properties of water repellents, results do not necessarily relate to the long -term 
performance of water -repellent -treated timber under all conditions of use.  
5 Marking  
5.1 General  
Preservative -treated timber, shall bear the following information legibly and indelibly marked, and  applied in 
accordance with 5.2 and 5.3, as relevant:  
 
a) The treater's identification, consisting of the name or the trade name or the trademark of the  preservation 
plant that undertook the t reatment;  
 
b) The symbol of the hazard class of the treated timber, in accordance with tables 1 and 2, e.g. H4, but in  the 
case of timber treated in accordance with the requirements given in table 3, the symbol Y3 in  addition to the 
hazard class, i.e. H4Y3 ; 
 
c) When  relevant, in addition to the symbol H0, the letter "i" for insects excluding termites, or "it" for  insects 
including termites; and  
 
d) in the case of round timber the specification number, i.e. 1288 and the last two digits of the  year during 
which the unit was treated (e.g. 00 for 2000).  
 
 
 
   
6 © UNBS 2019  – All rights reserved  
 5.2 Position of marking  
5.2.1 Stress -graded structural timber  
Each piece of stress -graded structural timber shall be marked on the end or face, following the rules, if  
relevant, given in 5.3.  
 
5.2.2 Laths, s takes and garden edging  
In every bundle of laths and loose garden edging and joined garden edging, one piece shall be  permanently 
marked on one end using an acceptable method. (Acceptable methods are given in  annex B).  DUS 2026 :2019  
© UNBS 2019  – All rights reserved  7 
 Table 1 — Requirements of preservati ve-treated softwood with  
a service life of at least 20 years  
 
1 2 3 4 5 6 7 
Hazard  
class  Exposure  
class  Timber  
application  End use  Type of  
preservative  Minimum  
average net  
retention 
kg/m 3 Minimum  
penetration 
of 
preservative 
mm  
H6 Marine  Timber  constantl y 
or periodically in  
contact with  
estuarine or  sea 
water and  subject 
to marine borer  
attack  Piling a; Retaining  walls  
Slipways  Groynes  Jetties  
Walkways  CCA  
plus 
Creosote  24 
plus 
200 Complete  
sapwood b 
H5 Fresh 
water  Timber  
constantly or  
periodically in  
contact with  
fresh water or  
heavy wet  
soils  Piling a; Retaining  walls  
Slipways  Culverts  
Groynes  Flood gates  
Jetties  Drains Walkways  CCA  
or 
Creosote  16 
or 
130 Complete  
sapwood b 
Industrial cooling  
towersc CCA  30 Complete  
sapwood  
H4 Ground  
contact  Timber in 
direct contact  
with the  
ground  Sawn rectangular  posts  
Landscaping  structures  
Playground  structures  
Building  Fencing  Pergolas; 
Car ports  Flower boxes  
Decking  Bridges;  CCA  
or 
Creosote  12 
or 
100 Complete  
sapwood b 
Rail bearers  
General purpose  
poles 
Piling a See hazard class H5  
H3 Exterior  
above  
ground  Timber not  in 
contact  with the  
ground but  
exposed to  
leaching  and 
weathering  Balustrades Fencing bearers 
and slats Outdoor decking  nd  
Beams Garden furniture 
Laminated beams Weather 
board Steps; Cladding  Stairs; 
Gates Fascia boards Plywood  
Sawn droppers Slabbed 
poles Cylindrical rails Half -
rounds  CCA  
or 
Creosote  8 
or 
80 Complete  
sapwood  
   General purpose  
poles  
Machined poles for  
log homes  20 
   Laths    5  
8 © UNBS 2019  – All rights reserved  
 H2 Internal  Timber used 
under a roof, not 
in contact with the 
ground and not 
exposed to 
leaching and  
weathering  Laminated beams Roof 
trusses Structural timber 
Ceiling boards Flooring  
Paneling  Doors Cupboards  
Skirting Window frames 
Plywood  CCA or  
Creosote  
Or TBTN/P  
Or TBTOL d 
Or Borate 
(boric acid  
equivalent)  6 or 
80 or  
1,3 
or 
1 
or 
5 Complete  
sapwood  
General purpose pole  
Machined poles for log  
homes  20 
1 2 3 4 5 6 7 
Hazard  
class  Exposure  
class  Timber  
application  End use  Type of  
preservative  Minimum  
average net  
retention 
kg/m 3 Minimum  
penetration 
of 
preservative 
mm  
H0-i e Dry 
interior  Timber used  under a  
roof, not in  contact 
with the ground,  
exposed to  insects  
other than  termites,  
and not  exposed to  
fungal  attack or  
Leaching  and 
weathering  Mouldings  
Ceilings  
Flooring boards  
Joinery  Deltamethrin  0,003  Complete  
sapwood  
H0-it e 
Dry 
interior  Timber used under a 
roof, not in  
contact with the 
ground, exposed to  
insects  
including termites, 
and not exposed to  
fungal  
attack or leaching  
and weathering  Mouldings  
Ceilings  
Flooring board s 
Joinery  Deltamethrin  0,01 Complete  
sapwood  
 
NOTE Timber treated with TBTOL or borate could be used for hazard class H3, provided that the timber is continuously 
protected by a suitable well -maintained coating.  
 
a Preferably in round wood  form with compl ete envelope of sapwood, see SANS 457 -2, but if sawn timber is used, a large 
amount of sapwood shall be present.  
 
b To achieve the required retention, a large proportion of sapwood needs to be present.  
 
c Timber selected for 100 % sapwood.  
 
d This product will be banned (Department of Agriculture) from the SA market in line with decisions taken at the Stockholm 
Convention on POPs as from the end of March 2009.  
 
e The end uses for this hazard class, unlike the other hazard classes, are restricted to those gi ven in column 4 only. Only 
products included in column 4 shall be allowed to be treated.  
 DUS 2026 :2019  
© UNBS 2019  – All rights reserved  9 
 Table 2 — Requirements of preservative -treated hardwood with a  service life of at least 20 years  
1 2 3 4 5 6 7 
Hazard  
class  Exposure  
class  Timber  
application  End u se Type of  
preservative  Minimum  
average net  
retention kg/m 3 Minimum  
penetration of  
preservative 
mm  
H6 Marine  Timber  constantly or  
periodically in  
contact with  
estuarine or  sea 
water and  subject to  
marine borer  attack 
a Piling b; Retaining  walls  Slipways  
Groynes  Jetties  
Walkways  CCA  
plus 
Creosote  24 
plus 
200 Complete  
sapwood  
H5 Fresh water  Timber  constantly or  
periodically in  
contact with  fresh 
water or  heavy wet  
soilsa Piling b; Retaining  walls  Slipways  
Culverts  Groynes  
Flood gates  Jetties  Drains  
Walkway s CCA  
or 
Creosote  16 
or 
130 Complete  
sapwood  
Industrial cooling  
towersc CCA  30 Complete  
sapwood  
H4 Ground  
contact  Timber in  
direct contact  
with the  
ground a Sawn rectangular  posts  
Landscaping  structures  
Playground  structures  Building  
Fencing  Pergolas;  Car ports  
Flower boxes  Decking  Bridges  CCA  
or 
Creosote  12 
or 
100 Complete  
sapwood  
Rail bearers  Complete  
sapwood  
or 
13 
General purpose  poles  13 
Railway sleepers  and ties d Creosote  100 d Complete  
sapwood  
Piling b See hazard class H5  
H3 Exterior  
above  
ground  Timber not in contact  
with the ground but  
exposed t  
leaching  
and 
weathering  Balustrades Fencing bearers and 
slats Outdoor decking and beams 
Garden furniture  
Laminated beams Weather board 
Steps; Cladding Stairs; Gates 
Fascia boards Plywood  
Sawn droppers e 
Slabbed poles Cylindrical rails 
Half-rounds f CCA  
or 
Creosote  8 
or 
80 Complete  
sapwood  
General purpose  
poles  
Machined poles g for 
log homes  13 
Laths  5 
Round droppers  10  
10 © UNBS 2019  – All rights reserved  
 Table two continues  
1 2 3 4 5 6 7 
Hazard  
class  Exposure  
class  Timber  
application  End use  Type of  
preservative  Minimum  
average net  
retention kg/m 3 Minimum  
penetration of  
preservative 
mm  
H2 Internal  Timber used under a roof, 
not in contact with the 
ground and not exposed to 
leaching and weatherin g Laminated beams Roof  
russes Structural timber  
Ceiling boards Flooring  
Panelling Doors 
Cupboards  
Skirting Window frames 
Plywood  CCA  
or 
Creosote  
or 
TBTN/P  
or 
TBTOL h 
or 
Borate (boric  
acid 
equivalent)  6 
or 
80 
or 
1,3 
or 
1 
or 
5  
  
General purpose po le 
Machined poles g for 
log homes   
H0-ii Dry 
interior  Timber used  under a  roof, 
not in  contact with  the 
ground,  exposed to  insects  
other than  termites,  and not  
exposed to  fungal  attack or  
leaching  and 
weathering  Mouldings  Ceilings  
Flooring boards  
Joiner y Deltamethrin  0,003  Complete  
sapwood  
H0-iti Dry 
interior  Timber used  under a  roof, 
not in  contact with  the 
ground,  exposed to  insects  
including  termites,  and not  
exposed to  
Fungal  attack or  leaching  
And weathering  Mouldings  
Ceilings  
Flooring boards  
Joine ry Deltamethrin  0,01 Complete  
sapwood  
NOTE Timber treated with TBTOL or borate could be used for hazard class H3, provided that the timber is  
continuously protected by a suitable well -maintained coating.  
a The only hardwoods recommended are species with a  permeable heartwood. Sawn eucalyptus species are  
not suitable for hazard classes H6, H5 and H4.  
b Preferably in roundwood form with complete envelope of sapwood, see SANS 457 -3, but if sawn  
timber is used, a large amount of sapwood shall be present.  
c Tim ber selected for 100 % sapwood.  
d If refusal is reached before the required retention is attained, maintain the working pressure (minimum  
850 kPa) for 15 min at a temperature ranging between 80 °C and 100 °C.  
e Type WCCA preservatives shall not be used for  the treatment of sawn droppers.  
f The treatment of half -rounds with class W preservatives is not recommended.  
g Machined in such a way that the sapwood required for penetration is not disturbed.  
h This product will be banned (Department of Agriculture) fr om the SA market in line with decisions taken at  
the Stockholm Convention on POPs as from the end of March 2009.  
I The end uses for this hazard class, unlike the other hazard classes, are restricted to those given in  
column 4 only. Only products included i n column 4 shall be allowed to be treated  
 
 
 DUS 2026 :2019  
© UNBS 2019  – All rights reserved  11 
  
 
Table 3 — Requirements of preservative -treated softwood and hardwood  
products with a service life of at least 3 years.  
 
1 2 3 4 5 6 7 
Hazard  
class  Exposure  
class  Timber  
application  End use  Type of  
preservati ve Average  
net 
retention  
kg/m3 Minimum  
preservative  
penetration  
 
H4 Ground  
contact  Timber in  
direct  
contact with  
the ground  Stakes  
Garden  
edging  Sawn  
timber  
 CCA  
or 
Creosote  6 
or 
80 SW HW 
Complete  
sapwood  Complete  
sapwood  
Round  
timber  5 5 
 
5.2.3 General purpose poles, cylindrical rails, half -rounds, rail bearers and slabbed  poles  
The end or face of each unit shall be permanently marked using an acceptable method. (Acceptable  methods 
are given in annex B.) Where face marking is use d, the mark shall be at the appropriate  position, i.e. mid  
length and recessed.  
 
5.2.4 All other sawn timber products  
Each piece of preservative -treated timber, or in the case of a package of units or a bundle of pieces (e.g.  
brandering, battens and floori ng strips), the package or bundle and at least one piece in the package or  
bundle shall be marked, following the rules, if relevant, given in 5.3.  
 
5.3 Rules to be observed in M arking  
The following rules shall be observed when marking is undertaken by mean s of inked stamps:   
 
a) If the timber complies with a Uganda national  standard, the marking shall be in signal red (colour)  If the 
timber does not comply with a Ugandan  national standard,  the marking shall be black;  
 
b) Whenever  possible, other markings sh all not be obliterated;  
 
c) pieces containing glue lines shall not be marked as suitable for hazard classes H6, H5, H4 and H3,  unless 
the adhesive that was used is of class 1  and  
 
d) Pieces  that have been reshaped in any way after preservative treatment ( the obtaining of test  specimens in 
accordance with 6.2 and 6.3 by means other than cross -cutting shall not be regarded  as reshaping) shall not 
be remarked as in 5.1, unless  
 
1) An acceptable additional treatment has been applied, or  
 
2) Compliance  of the r eshaped piece with the appropriate requirement of this standard for  penetration of 
preservative has been established.  
 
  
12 © UNBS 2019  – All rights reserved  
  
6 inspection and methods of test  
Examine each piece in the sample taken in accordance with annex C for compliance with the relevant  
requirements of clauses 4 and 5.  
 
6.1 Test specimens  
Where relevant, use all the pieces or units taken in accordance with C.2.2 (see annex C) for assessment  of 
compliance with the applicable requirements of clause 4 in accordance with the appropriate methods  given in 
6.2 to 6.5 (inclusive).  
6.2 Moisture content  
6.2.1 General  
Prepare test specimens in accordance with DUS 2039   and then use the appropriate of the methods  given in 
6.2.2 or 6.2.3 to determine the moisture content of each specimen to the nearest 1 0 g/kg.  
 
6.2.2 Untreated units  
In the case of untreated timber, use the oven -dry method given in DUS  2014 , or use the electric  moisture -
meter method given in   DUS 2016 . 
 
6.2.3 Treated units  
In the case of units treated with a class C preservative, use the  extraction method given in DUS 2015 or  in the 
case of units treated with a class O preservative, use the electric moisture meter given in DUS 2016  
 
6.3 Penetration of preservative and presence of sapwood  
Use DUS 2017,  or in the case of borate treatment,   
 
6.4 Retention of preservative  
 
6.4.1 Unless 6.4.2 is applicable, determine the average net retention of preservative  
a) By the sample method given in  DUS 2018,  or 
 
b) By the weighbridge method given in DUS  2019,  or 
 
c) Provided that the volume of preserv ative required to treat the charge in terms of the standard can be  
gauged to within 1 %, by the volume method given in DUS 2013 , or 
 
d) When  borate was used, .  
The average net retention is determined by using the volume of the timber in a charge. The aver age volumes 
for general purpose poles, laths, round stakes and garden edging is given in annex D.   
 
NOTE The individual net retention is assessable only in cases where the sample method of determining average  net 
retention is used.  
 DUS 2026 :2019  
© UNBS 2019  – All rights reserved  13 
 6.4.2 Determination of the average net retention of preservative by quantitative analysis of test  
specimens can be used but only when this, and the methods of sampling and test to be used, have been  
agreed upon between the supplier and the purchaser (see A.2).  
 
NOTE  Each load in  a charge may be considered as a separate charge, provided that the average net retention for  each 
load is determined.  
 
6.5 Determination of water repellency  
Use SANS 5990 to determine the short -term water repellency to liquid water of timber treated with a 
class W or class O preservative containing a water repellent.  
 
 
Annex A  
(Normative ) 
Notes to purchasers  
 
A.1 The following requirements shall be specified in tender invitations and in each order or contract:  
 
a) the hazard class, the end use, and the cla ss or type (or both) of the preservative(s) (see 4.4);  
b) the depth of penetration of heartwood if other than as specified (see 4.5.1); and  
c) when relevant, that a water repellent be added (see 4.7).  
A.2 The following can be agreed upon between the suppli er and the purchaser:  The use of 
quantitative analysis to assess average net retention of preservative, and the methods of  sampling 
and test to be used (see 6.4.2).  
 
 
 
Annex B  
(Informative ) 
Marking methods  
 
B.1 Mild steel and A luminium identification tags  
 
B.1.1 All tags should be of diameter at least 25 mm. The mild steel tag should be of thickness at 
least  0,5 mm and should be galvanized in accordance with class Z275 of US 301 . The aluminums  
tag should be of thickness at least 0,9 mm.  
 
B.1.2 Each tag shou ld be attached by means of a skirt of thickness at least 5 mm or a galvanized 
nail of length at least 30 mm and diameter at least 2,5 mm. Nails should have a galvanizing 
thickness of at  least 25 μm.  
 
B.1.3 Letters and figures should be of height at least 3,5 mm.  
 
B.2 Branding  
The letter height, after branding, should be at least 8 mm, with the branding width and depth at least   
14 © UNBS 2019  – All rights reserved  
 Annex C  
(Normative ) 
Quality verification of preservative -treat ed timber and  assessment of 
compliance  
 
C.1 Quality verification  
 
C.1.1 When a purchaser requires ongoing verification of the quality of the preservative -treated 
timber,  it is suggested that, instead of concentrating solely on the evaluation of the final p roduct, he 
also direct  his attention to the manufacturer's quality system. In this connection it should be noted 
that SANS 9001  covers the provisions of an integrated quality system.  
 
C.1.2 If no information about the implementation of quality control or testing during manufacture is  
available to help in assessing the quality of a lot, and a purchaser wishes to establish, by inspection 
and testing of samples of the final product, whether a lot (as defined in C.2.1.2) of the product 
complies with  the standa rd, use the sampling plan given in C.2.2. It must be noted that such a 
sampling plan applies to  the final product only.  
 
C.2 Assessment of compliance with the standard  
NOTE It is not possible to establish compliance with all the requirements of this stand ard in the case 
of lots  (consignments) for which no acceptable treatment records were kept by the treated . 
 
C.2.1 Definitions  
 
C.2.1.1  
defective  
a piece, or charge of preservative -treated timber, that fails in one or more respects to comply with 
the releva nt requirements of the standard   
C.2.1.2  
lot 
not less than 10 and not more than 10 000 pieces or units of preservative -treated timber of the 
same  species (or species group), nominal cross -sectional dimensions and hazard class and 
impregnated with  the same type of preservative from one manufacturer, submitted at any one time 
for inspection and  testing  
C.2.2 Sampling  
The following sampling procedure shall be applied in determining whether a lot complies with the  
relevant requirements of the standard. The samp le so drawn shall be deemed to represent the lot. 
After  checking the lot for compliance with the requirements of clause 5, draw from it at random the 
number of  pieces or units of preservative -treated timber given in column 2 of table C.1, relative to 
the a ppropriate  lot size given in column 1.  
 
C.2.3 Criteria of compliance  
A lot shall be deemed to comply with the relevant requirements of the standard if, on inspection and  
testing of the sample taken in accordance with C.2.2, the numbers of defectives found do not 
exceed the  appropriate acceptance numbers given in columns 3 and 4 of table C.1.  
NOTE See also note 1 to clause 1.  
 DUS 2026 :2019  
© UNBS 2019  – All rights reserved  15 
  
Annex D  
(Informative ) 
Average volumes of general purpose poles,  laths, round stakes and garden edging  
The volumes for general purpos e poles, laths, round stakes and round garden edging are given to 
assist  in the calculation of retention requirements.  
 
NOTE The volumes for softwood and hardwood general purpose poles, laths, stakes and garden 
edging are  calculated on the average of the a ctual diameter of the class, e.g. 50 mm to 79,999 mm, 
and a taper of 7 mm/m.  
 
D.1 General Purpose  poles  
Tables D.1 and D.2 give the average volume of softwood and hardwood general purpose poles  
respectively .  
16 © UNBS 2019  – All rights reserved  
 Bibliography  
[1] SANS 12888, Preservative -treate d timber  
 US nnnn -n: yyyy  
© UNBS  2019  – All rights reserved  17 
 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 product 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.  
 
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ICS nn.nnn.nn  
Price based on nn pages  
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