AFRICAN 
STANDARD  DARS  
1098: 2023  (E)  
First Edition 2023 
 
 Reference No. DARS 1098 :2023(E) 
ICS 67.060 
 
 
© ARSO 2023 
 
 
 
 
 
 
 
 
 
 
 
Agricultural Structures – Warehous es for the storage of bagged 
grains  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 DARS 1098 : 2023(E)  
 DARS 1098 :2023(E) 
ii © ARSO  2023 — All rights reserved   
Table of Contents  
Foreword  ................................ ................................ ................................ ...............................  iii 
AFRICAN STANDARD  ................................ ................................ ................................ ........   
1 Scope  ................................ ................................ ................................ ............................  1 
2 Normative references  ................................ ................................ ................................ .... 1 
3 Terms and definitions  ................................ ................................ ................................ .... 1 
4 Location  ................................ ................................ ................................ ........................  2 
5 Functional Requirements  ................................ ................................ ...............................  3 
5.1 Product sectionalism ................................ ................................ ..............................  3 
5.2 Floor area requirement  ................................ ................................ ..........................  3 
5.2.1 Pallet  dimension  ................................ ................................ ................................  3 
Table 1 – Recommended dimension for pallet  ................................ ................................ ...... 3 
Table 2 – Recommended stack heights  ................................ ................................ ................  5 
Table 3 – Recommended stacking density  ................................ ................................ ............  5 
6 Structural Requirements  ................................ ................................ ................................  6 
7 Warehouse Management  ................................ ................................ ..............................  8 
 
 
 
  DARS 1098 :2023 (E) 
© ARSO  2023 — All rights reserved  iii Foreword  
 
The African Organization for Standardization (ARSO) is an African intergovernmental organization 
established by the United Nations Economic Commission for Africa (UNECA) and the Organization of 
African Unity (AU) in 1977. One of the fundamental mandates of  ARSO is to develop and harmonize 
African Standards (ARS) for the purpose of enhancing Africa’s internal trading capacity, increase 
Africa’s product and service competitiveness globally and uplift the welfare of African communities. 
The work of preparing A frican Standards is normally carried out through ARSO technical committees. 
Each Member State interested in a subject for which a technical committee has been established has 
the right to be represented on that committee. International organizations, Regio nal Economic 
Communities (RECs), governmental and non -governmental organizations, in liaison with ARSO, also 
take part in the work.  
 
ARSO Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.  
 
The main task of techni cal committees is to prepare ARSO Standards. Draft ARSO Standards 
adopted by the technical committees are circulated to the member bodies for voting. Publication as an 
ARSO Standard requires approval by at least 75 % of the member bodies casting a vote.  
 
Attention is drawn to the possibility that some of the elements of this document may be the subject of 
patent rights. ARSO shall not be held responsible for identifying any or all such patent rights.  
 
This African Standard was prepared by the ARSO Technical  Committee on Cerels, Pulses and 
Derived Products  (ARSO/TC 12). 
 
 
 
 
 
© African Organisation for Standardisation 2023 — All rights reserved* 
 
ARSO Central Secretariat  
International House 3rd Floor  
P. O. Box 57363 — 00200 City Square  
NAIROBI, KENYA  
 
Tel. +254 -20-2224561, +254 -20-3311641, +254 -20-3311608  
 
E-mail: arso@arso -oran.org  
Web: www.arso -oran.org  
  
                                                 
* © 2023 ARSO — All rights of exploitation reserved worldwide for African Member States’ NSBs.  DARS 1098 :2023(E) 
iv © ARSO  2023 — All rights reserved   
Copyright notice  
 
This ARSO document is copyright -protected by ARSO. While the reproduction of this document 
by participants in the ARSO standards development process is permitted without prior 
permission from ARSO, neither this document nor any extract from it may be reproduced, stored 
or trans mitted in any form for any other purpose without prior written permission from ARSO.  
 
Requests for permission to reproduce this document for the purpose of selling it should be 
addressed as shown below or to ARSO’s member body in the country of the request er: 
 
 
© African Organisation for Standardisation 2023 — All rights reserved  
 
ARSO Central Secretariat  
International House 3rd Floor  
P.O. Box 57363 — 00200 City Square  
NAIROBI, KENYA  
 
Tel: +254 -20-2224561, +254 -20-3311641, +254 -20-3311608  
 
 
E-mail: arso@arso -oran.org  
Web: www.arso -oran.org  
 
Reproduction for sales purposes may be subject to royalty payments or a licensing agreement. 
Violators  may be prosecuted.  
 
 
 
 
 
  DARS 1098 :2023 (E) 
© ARSO  2023 — All rights reserved  v  DARS 1098 :2023(E) 
© ARSO  2023 — All rights reserved    
Agricultural Structures – Warehouses for the storage of bagged 
cereals and pulses  
 
1 Scope  
 
This standard specifies the requirements for warehouses for bag type storage of cereals and pulses . 
It does not include storage for seeds.  
 
 
2 Normative references  
 
The following referenced documents are indispensable for the application 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.  
 
 
3 Terms and definitions  
 
For the purpose of this standard the following terms and definition s shall apply . 
 
3.1 
aeration  
movement  of air through stored grains at low airflow rates for purposes other than drying, to maintain or 
improve its quality  
 
3.2 
bag type storage  
storing of grains in bags usually made of jute, polyethylene, and other packaging materials.  
 
3.3 
dunnage  
pallet  
wooden or plastic (food grade) frames used on concrete floors for stacking bags to prevent direct 
contact between the grains and t he floor  
 
3.4 
fumigation  
process of using permitted fumigants  to control insects in grains in a form of fumes  
 
3.5 
moisture content  
amount of water in the grains, expressed as percentage  
 
3.6 
warehouse  
building for storage of cereals and pulses meant for t rade, exchange and food security programmes  
 
Note: A typical warehouse is shown in Figure  1. 
AFRICAN STANDARD  DARS 1098:2023(E)  
2 © ARSO  2023 — All rights reserved   
 
Figure 1 – Typical warehouse for bag type storage of grains  
 
 
4 Location  
 
The warehouse should be constructed away from sources of potential hazards that may affect the 
quality of produce and pose risk to the worker’s health and safety.  
 
The warehouse should be located away from:  
 environmentally polluted areas;  
 sources of unsafe industrial activities that may impact  on the safety/contaminate the stored 
grains;eg cement, tobacco, batteries ; 
 flood prone areas;  
 fire hazard;  
 zones that may encourage insect infestation and entry of stray animals; and  
 places where waste either solid or liquid cannot be removed effectively.  
The warehouse should be constructed where there is accessible road. It shall be accessible to 
relevant  forms of transport system. There should be ample space to facilitate movement and 
manoeuvring of vehicles within the location.  
The load -bearing capacity,  resistance to compaction and drainage characteristics of soil in which the 
warehouse is to be constructed should be considered.  
The location and distance of the warehouse from other farm structures or the production area should 
also be considered during c onstruction.  
The long axes of the warehouses should be oriented East -West or sited across the prevailing wind.  
 
Warehouses shall not be located near busy public facilities such as schools, hospitals, etc. 
Surroundings in the vicinity shall conform to exist ing safety and sanitary measures.  
 
The structure shall be built on a stable ground soil.  Space shall be provided for future expansion.  
Electricity, communication, water services and drainage shall all be available and reasonably 
economical.  
 
DARS 1098 :2023(E) 
© ARSO  2023 — All rights reserved   5 Functional Requirements  
 
5.1 Product sectionalism  
 
Warehouse operations shall be identified and analysed as to space requirements of the commodity 
and the in -out flow of stocks from one operation to another and identify the proper places of every 
operation.  
 
The inte rnal layout of the depot shall be designed in accordance with the First in -First out method of 
holding inventory.   
Quality and quantity of the stored grains should be monitored.  
 
5.2 Floor area requirement  
 
5.2.1  Pallet  dimension  
 
The recommended dimension for the pallet to be used is shown in Table 1.  
 
Table 1 – Recommended dimension for pallet  
 
Shape  Dimension  
Square  152 cm x 61 cm  
Rectangular  120±1cm x 100±1cm x 72±1cm  
Square  120±1cm x 120±1cm x 72±1cm  
 
5.2.2  System of piling  
 
5.2.2.1  Small scale  storage  
 
Bags of grain in each lot should be stacked in basic patterns of cluster formation (Figure 2) for easy 
inventory and quality maintenance/assessment.  
 
 
Figure 2 – System of piling for small scale  
 
5.2.2.2  Large scale storage  
 
5.2.2.2.1  Block  stacking  
 
In this type, six blocks are formed to make standard stack of 9.14m x 6m size. Each block is of the 
size 6m x 1.5m. In the block, one layer is put lengthwise and other breath -wise.  
 
5.2.2.2.3 Chinese method  
 
Bagged grains with 14% moisture content or lower could be piled in Chinese method. Sacks are piled 
side by side and one on top of the other for appropriate pest control measures (Figure 3).  
 
DARS 1098:2023(E)  
4 © ARSO  2023 — All rights reserved  
 
 
 
Figure 3 – Chinese piling  
 
 
 
 
 
 
 
 
 
 
 
 
Figure 4 – Japanese piling  
 
 
5.2.2.2.4 Japanese  method  
 
Bagged grains with moisture content 14.1% to 15% are to be piled in this method. This system of 
stacking provides ventilation space between bags and allows circulation of convective air currents that 
provide a medium for heat dissipation (Figure 4).  
 
5.2.2.2.5 Criss -cross stacking  
 
In this type bags are laid in complete length -wise or breath -wise tiers in alternate layers 
systematically. The first layer will have 11 bags in 9.14m direction with 11 such rows. The second 
layer of bags would be laid width -wise with 16 bags in 9.14m direction of stack with  7 such rows.  
 
5.2.3  Stack height  
 
5.2.3.1  The height of stacks shall not exceed the height of the walls and a space of at least 1 m 
shall be allowed between the tops of the stacks and roof  frames.  
 
5.2.3.2  Sacks made of woven polypropylene have a tendency to slide on each other, and therefore 
shall not be stacked more than 3 m high. Jute sacks bind together better, and maybe stacked up to 
6 m above the floor.  
 
5.2.3.3  Factors like nature of grain, size, weight, and shape and strength of grain bag to stand the 
height of stack have direct bearing on stack height. Table 2 shows the optimum stack heights 
recommended for grain storage.  
 
DARS 1098 :2023(E) 
© ARSO  2023 — All rights reserved   Table 2 – Recommended stack heights  
 
Type of grain  Maximum stack height inlayers  Stack height, m  
Wheat, barley and corn  18 4.57 
Paddy  16 6 
Rice 16 5.5 
 
5.2.3.4  The size of the piles should conform with fumigating sheets in situations where warehouses 
cannot be made airtight. Dimensions for maximum piling should be  7.3 m x 21.9  m x 4.5m.  
 
5.2.3.5  Piles should be tight, neat and squared off. 
 
5.2.3.6  The recommended bag warehouse capacity is shown in Table 3.  
 
Table 3 – Recommended stacking density  
 
Stacking Density  Number of bags per cubic meter  
Paddy  10 
Rice 15 
Corn  12 
 
5.2.4  Pathways  
 
5.2.4.1  A central pathway should be 2 m wide or not less than 1m wider than the width of the 
widest forklift trucks that are being used simultaneously during warehouse operation.  
 
5.2.4.2  If there is a forklift or mechanical handling equipment to be used, the central pathway 
should be designed with a width of not less than 0.6  m wider than the width of the widest vehicle  
loaded.  
 
5.2.5  Side spacing  
 
5.2.5.1  Space between piles shall be 1m wide.  
 
A minimum of 1m space between the edge of the pile and the wall shall be provided.  
 
5.3 Physical dimensions of structure  
 
Table 4 – Warehouse dimensions based on the number of bags  
 
Number of bags (1 bag = 50kg)  Dimensions  
10,000  10 m x 30 m  
30,000  16 m x 48 m  
50,000  20 m x 60 m  
100,000  25 m x 78 m  
500,000  75 m x 142 m  
 
NOTE  There may be special designs of warehouse for irregular shaped  lot. 
 
Given the recommended dimensions of the warehouse and its corresponding capacity above (Table 
4), the number of buildings is doubled, tripled or quadrupled based on the desired capacity of the 
warehouse. For example , a 200,000 bags warehouse is required, two bui ldings (duplex) with 
dimensions of 25m x 78m each is recommended.  
 
5.4 Height of structure  
 
The recommended height between the eaves line and the floor is 7 m and 2.5 m between the eaves 
line and the apex.  DARS 1098:2023(E)  
6 © ARSO  2023 — All rights reserved   
 
5.5 Illumination  
 
There should be provisions for sky lightings. Skylights should be placed in the aisle.  
 
5.6 Electrical works  
 
Receptacles for transporting equipment and wire distribution for electric fans shall be provided. If 
possible, conduit tubes shall be used. Electrical works should conform with the applicable national 
Electrical Code . 
 
5.7 Drainage  
Sufficient drainage shall be provided to prevent flooding.  
 
6 Structural Requirements  
 
6.1 Building structure requirements  
 
6.1.2  There shall be provisions for water tightness, to prevent moisture from leaching to the 
grain.  
 
6.1.3  There shall be provisions for efficient loading and unloading bays.  
 
6.1.4  There shall be provisions for aeration.  
 
6.1.5  There shall be provisions for bird and rodent proofing and for fumigation.  
 
6.1.6  The building shall have a clear inside span and has no inside pillars  which could obstruct 
stacking arrangement.  
 
6.1.7  The building should have a ledge or podium.  
 
6.2 Foundation  
 
The construction shall conform with the National Building Code.  
 
6.3 Floor  
 
6.3.2  The floor should be adequately strong and capable of withstanding heavy loads and 
vibrations.  
 
6.3.3  The floor shall be elevated or constructed higher than the existing ground. The floor 
should be 1m above the ground to permit easy loading or unloading into trucks at the sides of the 
warehouse.  
 
6.3.4  There shall be provisions for wear resistance and safety (refractoriness and elimination of 
skidding risks).  The floor should be smooth and easy to clean. It should be free from cracks where 
moisture from the ground may affect the stored grain. Moisture sealing compound or asphalt should 
be provided t o fill the floor cracks against moisture.  
 
6.3.5  Foundation, pillars and beams should be made from reinforced concrete. Floor 
construction should conform with the National Building Code.  
 
6.4 Walls  
 
6.4.2  The internal surfaces of the walls shall be smooth and free from pr ojections to eliminate 
dust-laden surfaces, facilitate cleaning of the warehouse.  
 
6.4.3  Gravel concentrations in concrete walls, protruding brick work, horizontal planes or rims, DARS 1098 :2023(E) 
© ARSO  2023 — All rights reserved   window sills, protruding door or window posts and other ledges should either be av oided completely 
or be shedded at a minimum angle of 60°.  
 
6.4.4  The walls shall be painted white, on the inside to facilitate the detection of insect pests 
and on the outside to help keep the warehouse look as cool as possible and for sanitary purposes.  
 
6.4.5  There shall be no opening between wall and roof.  
 
6.4.6  A water/damp -proof barrier should be incorporated into the base of the walls. 
Waterproofing compound should be incorporated during the plastering and finishing of the walls.  
 
6.4.7  A concrete strip about 1 m wide shall  be laid around the warehouse to prevent rain from 
eroding the base of the walls below the damp course.  
 
6.4.8  Wall construction should conform with the National Building Code.  
 
6.5 Roof  
 
6.5.2  Internal pillars supporting roof frames shall be avoided because it can interf ere with the 
pest control and other stock management procedures. A standard roof truss of 14.5mspan (or 
larger) should be used.  
 
6.5.3  Roof frames made of wood or steel shall be designed so that they transfer the weight of 
the roof to the supporting columns or t o the walls.  
 
6.5.4  It must be provided with the necessary lateral and vertical wind brace to resist forces due 
to strong winds and earthquakes.  
 
6.5.5  The strength of the roof construction should be sufficient to handle the weight of the 
strongest winds that can be e xpected.  
 
6.5.6  The roofing materials made of galvanized iron sheets and shall be in light colors (white or 
beige).  The external surface should be reflective or light colored to minimize the amount of heat that 
it can absorb.  
 
6.5.7  The chosen materials may be fire proof and with refractory.  
 
6.5.8  The inclination of the roofs should be sufficient to drain rainwater quickly, taking into 
account that the water may be forced up by the wind.  
 
6.5.9  Rainwater drainpipes should be closely spaced, of sufficient size and installed with out 
bends.  
 
6.6 Doors  
 
6.6.2  There shall be at least two doors so as to be able to rotate stocks on a first in, first out 
basis.  
 
6.6.3  The door shall be wide for easy access, yet fit tightly for insect control and fumigation. Roll 
up doors are generally used because of i ts capability to close tightly.  
 
6.6.4  Preferably the door shall be made of steel or at least reinforced along their lower edges 
with metal plate as protection against rodents.  
 
6.6.5  If sliding or folding doors are fitted, they shall be opened outwards in order not t o reduce 
the storage capacity of the warehouse.  
 
6.6.6  The size of the entrance is 6 m wide and 4 m high for normal temperature warehouse.  
A canopy shall be constructed over every entry door to allow continuous loading and unloading even 
when it rains.  DARS 1098:2023(E)  
8 © ARSO  2023 — All rights reserved   
6.7 Ventilation  
 
6.7.2  Vents should be provided near the floor level, at the top of the walls near the grid line and at 
the top of the roof and the ridge.  
 
6.7.3  Ventilation openings such as louvers shall be fitted on the outside with anti -bird grills (20mm 
mesh) and on t he inside (10 cm behind the grills) with insect screens (removable for cleaning), 
which will deter most insects.  
 
6.7.4  Adequate natural ventilation openings shall be provided with shutters so that ventilation may 
be controlled.  
 
6.7.5  Continuous ridge vent s are built  on the roof top which provide good ventilation in addition to 
the louvers all over the warehouse.  
 
6.7.6  In addition to natural ventilation exhaust fans should be installed.  
 
6.8 Rodent proofing  
 
If the structural set -up of doors is unsatisfactory the rodent barrier may be attached. An iron sheet 
used for rodent barrier should have an optimum size but will not obstruct the entrance and will not 
impede mobility. As shown in Figure 5, its height should be little over 60 cm and fixed by a mortise 
and tenon joint or by hinge. Polished artificial stone is usually used for wall rodent barrier.  
 
 
 
Figure 5 – Rodent barrier  
 
 
On all possible entries within the warehouse, there should be a screen for bird and rodent control.  
 
 
7 Warehouse Management  
 
7.1 Fumigation  
 
In cases of insect infestation and presence of mold, fumigation should be carried out. The appropriate 
pest control should be used for insect pests or microorganisms. During fumigation dosage of the 
chemical and airtight conditions must be carefully  observ ed. 
 
Fumigants should be kept in a special locked storage room.  
 
7.2 Facility requirement  
 
7.2.2  Quality control laboratories  
 
7.2.3  Workshops  
DARS 1098 :2023(E) 
© ARSO  2023 — All rights reserved    
7.2.4  Garage for vehicles  
 
7.2.5  Dead stock store  
 
7.2.6  Bag stacker  
 
7.2.7  Pest control chemicals store  
 
7.2.8  Isolation shed  
 
7.2.9  Restrooms and washing facilities and accessible facilities  
 
7.2.10  Personnel office  
 
7.3 Safety  
 
7.3.2  Guards for machines should be provided.  
 
7.3.3  Illuminations should be sufficient and should have a cover guard.  
 
7.3.4  Warning signs or boards shall be fixed in hazardous/dangerous places and exits and m ust 
be visible on other places.  
 
7.3.5  There shall be a provision for fire control equipment as provided in the applicable  Building 
Code.  
 
7.3.6  There shall be provisions for first aid kit.  
 
7.3.7  There shall be provisions for proper exhaust and ventilating system.  
 
7.3.8  There shall be provisions of PPE for people accessing the ware house  
 
7.3.9  There shall be a provision for fire control equipment and a fire assembly point as provided in 
the applicable Building Code.  
 
All warehouses shall be identified by their warehouse name, code a nd location printed on a standard 
billboard exhibited outside the warehouse.  
 
 
 
 
  DARS 1098:2023(E)  
10 © ARSO  2023 — All rights reserved  ANNEX A  
(Informative)  
Sample Design of a Standard Warehouse (Capacity 100,000 bags)  
 
A.1 Floor  Plan  
 
 
 
 
DARS 1098 :2023(E) 
© ARSO  2023 — All rights reserved   A.2 Elevation  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
DARS 1098:2023(E)  
12 © ARSO  2023 — All rights reserved