By the end of this chapter, you will be able to:
Mastering these skills will help you design, assess, and maintain farm structures safely and to professional standards in the real world of agriculture.
Compiled by: Joyce Waweru
Designing farm structures is crucial for optimizing productivity, ensuring sustainability, and maintaining safety in agricultural enterprises across Kenya. Well-designed farm structures support efficient resource use and enhance the welfare of both workers and livestock. In diverse settings such as county farms, agricultural cooperatives, and rural schools with farming projects, understanding the principles of farm structures design enables professionals to meet operational needs while complying with regulatory standards.
Design is the stage between the farm plan and construction. It turns the need for a structure, such as a milking shed for twenty cows or a store for five tonnes of maize, into dimensions, materials and drawings that a builder can follow. A good design makes the structure strong, suitable for its use, economical to build and easy to maintain, while a poor design may make the structure too small, hot, wet or weak, and the faults are costly to correct once the walls are up. This topic covers the terms used in design, the types of designs, the factors that decide a design, the importance of design, the calculation of areas, volumes and scales, and the drawing of farm structures plans.
The following terms are used throughout farm structures design.
A farm structure is any built facility that supports farming activities, such as a cattle shed, a poultry house, a grain store, a water tank, a milking parlour, a fence or a greenhouse. Each is designed for one main purpose, and it is the purpose that decides its form.
Design is the process of deciding the shape, size, materials and details of a structure and recording them in drawings and specifications. It takes account of the use of the structure, the site, the materials, the budget and safety.
Scale is the ratio between a length on a drawing and the real length on the ground. A scale of 1:50 means that 1 cm on the drawing stands for 50 cm on the ground, which allows a large building to be shown on a sheet of paper.
A plan is a scaled drawing that shows the layout and dimensions of a structure, as seen from above for a floor plan, or the position of structures on a site for a site plan. It guides the builder and the person who checks the work.
Area is the amount of surface a structure covers, such as the floor area of a shed, measured in square metres (m²).
Volume is the space enclosed in a structure or container, measured in cubic metres (m³). It determines the air available for ventilation, the capacity of a store and the amount of water a tank holds.
Structures can be designed with different emphasis depending on their purpose and surroundings. In practice a good design combines more than one type.
A functional design puts the use of the structure first. The layout, the openings and the finishes are arranged so that the work done in the structure is easy and efficient. Example: a maize store with raised floors and ventilation openings to keep grain dry and prevent spoilage.
A structural design concerns the strength and stability of the structure: the foundation, the walls, the roof frame and the connections, which must carry the weight of the building and resist wind and rain. Example: a roof frame of a greenhouse designed to withstand strong wind.
An environmental design makes use of the climate and the site to reduce energy use and improve comfort. It uses natural light and ventilation, shade and local materials. Example: a poultry house with open sides and wide roof overhangs aligned to receive the breeze and avoid the afternoon sun.
A modular design builds the structure from standard units that can be added to or taken away. Example: a goat house built in pen units of the same size, so that more pens are added as the herd grows.
The use decides the size, the layout and the materials. A pig unit needs washable floors and drainage, a milking parlour needs a clean milk room and a hay store needs dry floors and good air movement.
Temperature, rainfall, wind and sunshine affect the roof slope, the size of overhangs, the number of openings and the materials. A hot, dry area needs shade and good ventilation, and a wet area needs strong drainage and a roof that sheds water quickly.
Materials that can be found near the farm cost less to transport. Stone, timber, sand and blocks from nearby sources reduce the cost, while a design that depends on materials from far away raises both cost and delay.
The money available limits what can be built. A smallholder may build a simple timber and iron-sheet shed, while a larger enterprise can afford concrete, steel and mechanised equipment. The design is adjusted to the budget without reducing safety.
The slope, soil and drainage of the site affect the foundation and the position of the structure. A sloping site may need a stepped foundation, and a low-lying site needs raised floors or drains to deal with floods.
A well-designed structure makes work flow smoothly. A feed store beside the animal house and a milking parlour with a good animal path reduce the time and labour needed for daily tasks.
Good design provides ventilation, light, drainage and sound structure, which protect people and animals from injury, damp and disease. A dairy shed with good airflow and a dry floor reduces respiratory problems and lameness.
A design that uses durable materials and protects timber and metal from damp and termites lowers the cost of repairs over the life of the structure.
A design that arranges rooms, pens and alleys well uses the land and the building efficiently, so that more animals or produce are handled in the same space.
Designs have to follow local building and environmental rules, including those for waste disposal and the distance from water sources and neighbours. A design that complies avoids delays, penalties and demolition.
Dimensions are calculated before drawing. The three basic calculations are floor area, volume and the length on the drawing.
The floor area depends on the number of animals and the space each needs. For a rectangular floor, area = length × width. Example: assume a design allows 1.5 m² for each goat. For 20 goats the floor area is 20 × 1.5 = 30 m². A house 6 m long and 5 m wide gives 6 × 5 = 30 m², which meets the need.
Volume = floor area × height. For the goat house above with an average height of 2.5 m, the volume is 30 × 2.5 = 75 m³. The volume matters because air carries away the heat, moisture and ammonia produced by the animals, so a house that is crowded or low needs more openings.
The length on the drawing = real length ÷ scale number. At a scale of 1:50, the 6 m length is 6000 mm ÷ 50 = 120 mm on the drawing, and the 5 m width is 5000 mm ÷ 50 = 100 mm. In reverse, a length measured on the drawing is multiplied by the scale number to find the real length. Write the scale on every drawing.
Leave space and strength in the design for growth, such as a foundation and roof frame that allow a house to be extended, so that the structure does not need to be rebuilt when the herd increases.
Use metric units for all lengths, areas and volumes, and give dimensions in the same unit (all in millimetres or all in metres) to avoid errors.
Ratios are used for scales, for concrete mixes and for proportions such as the ratio of window area to floor area. A designer who keeps the ratios consistent can scale a design up or down for a larger or smaller herd.
A farm structures plan is the set of drawings that tells the builder what to build and where. Plans also serve as a record of the structure and as a basis for cost estimates.
A good plan shows accurate dimensions, the scale, a north point, the symbols for doors, windows and drains with a key that explains them, notes on materials and a title that names the structure, the date and the person who drew it. It is neat and easy to read.
Computer-aided design (CAD) software draws accurate plans quickly and lets the designer change dimensions and copy repeated parts, such as pens, without redrawing. Plans can also be drawn by hand on drawing paper with a drawing board, set squares and a scale rule.
To read a plan, first check the title and scale, then follow the dimensions and symbols and compare the plan with the section and elevation. A builder who misreads a plan may build the wrong size or put openings in the wrong place, so questions are cleared with the designer before work starts.
Plans are changed when site conditions differ from what was expected or when the owner decides on improvements. Each change is dated and recorded, and everyone working on the site receives the revised plan so that they do not work from an old one.
This chapter explored the concept of farm structures design, beginning with clear definitions of key terms to establish a foundational understanding. It then examined the various types of designs commonly used in farm structures, highlighting their specific applications and characteristics. The discussion proceeded to identify the critical factors that influence the design process, such as environmental conditions, material availability, and functional requirements. The importance of having well-thought-out designs was emphasized, particularly in ensuring the durability, efficiency, and cost-effectiveness of farm buildings. Methods for determining the appropriate areas, volumes, and scales necessary for different farm structures were detailed to guide practical implementation. Finally, the chapter addressed the preparation and interpretation of farm structures plans, underscoring their role in communicating design specifications and facilitating construction. Together, these topics provide a comprehensive framework for understanding and executing effective farm structures design.
Question 1 key points:
Question 2 key points:
The Kisumu County Agricultural Cooperative plans to build a new grain storage facility to support local farmers.
Tasks:
a) Identify key factors that should guide the design of this storage facility. (6 marks)
b) Outline the steps involved in preparing the farm structure design plans for this project. (8 marks)
c) Explain how determining the volume and area requirements will affect the final design decisions. (6 marks)
a) Key factors include local climate conditions (humidity and rainfall), type and quantity of grain to be stored, security needs, accessibility for transport vehicles, availability of construction materials, and compliance with county regulations.
b) Steps:
c) Volume and area calculations determine the size of the storage facility, ensuring it can hold the expected grain quantities without overcrowding, allow for proper ventilation, and facilitate handling operations. Accurate sizing avoids under- or over-building, impacting cost and functionality.
Question 11 (Compulsory - 20 marks)
The Murang’a County Agricultural Training Centre plans to construct a multi-purpose farm structure to support training activities including livestock housing, storage, and classrooms.
a) Discuss the key factors that should be considered in designing this farm structure to meet diverse needs. (10 marks)
b) Prepare an outline of how to determine the appropriate area, volume, and scale for this structure, referencing practical steps the centre can take. (10 marks)
Question 12 (20 marks)
Explain the different types of farm structure designs and evaluate how each type contributes to efficient resource use on a commercial vegetable farm in Kiambu County.
Question 13 (20 marks)
Analyze the importance of farm structure plans in ensuring compliance with environmental regulations at a dairy cooperative in Nakuru County. Illustrate your answer with relevant design features.
Question 14 (20 marks)
A small-scale poultry farmer in Machakos County wants to build a new chicken house. Explain how budget constraints and local environmental conditions influence the design process, and propose strategies to optimize design under these limitations.
Question 11
a) Key factors include intended multifunctional use requiring flexible spaces; climatic conditions demanding adequate ventilation and protection; soil quality for foundation stability; accessibility for trainees and livestock; and compliance with safety and building codes. Consideration of future expansion and budget constraints is also essential.
b) Determining area involves assessing the number of trainees, livestock, and storage needs. Volume calculation ensures adequate air circulation and space utilization. Scale is set relative to training capacity and operational efficiency. Steps include site surveys, consultation with users, and application of standard space allowances per activity.
Question 12
Types of designs include conceptual (initial ideas), schematic (layout planning), detailed (construction specifics), structural (load-bearing elements), and functional (usability focus). Conceptual design allows for flexible planning; schematic design optimizes space; detailed design ensures safety and durability; structural design guarantees stability; and functional design enhances operational efficiency. On a commercial vegetable farm, these designs collectively minimize waste, reduce costs, and improve productivity.
Question 13
Farm structure plans provide detailed layouts that incorporate environmental safeguards such as waste management systems, erosion control, and water runoff management. For the dairy cooperative, plans ensure structures do not contaminate water sources and comply with NEMA regulations. Features like manure storage, drainage channels, and buffer zones are designed to protect the environment.
Question 14
Budget constraints limit material choices and design complexity, while local environmental conditions like high temperatures and seasonal rains dictate ventilation and roofing design. Strategies include using affordable local materials, modular designs for phased construction, and natural ventilation to reduce costs. Orientation of the structure to reduce heat gain and proper drainage design also optimize performance within budget limits.
Time: 2 Hours | Type: Individual
Resources Required:
At a poultry unit in Kisumu, the farm manager needs clear communication of farm structure components to the maintenance team. Accurate sketches ensure everyone understands technical terms.
Tasks:
i. Define and sketch the following farm structure terms: foundation, wall, roof, floor, and ventilation.
ii. Label each part clearly on your sketch.
iii. Using the graph paper, draw to scale one farm structure component (choose any).
iv. If available, replicate your sketch using CAD software and print it.
Assessor Observation Criteria:
Time: 1.5 Hours | Type: Group of 3
Resources Required:
In an agro-vet shop in Meru with agricultural loan clients, staff need to understand different farm structure designs to better advise members on farm improvements.
Tasks:
i. Review provided photographs and classify the farm structures into categories such as animal housing, crop storage, water management, and fencing.
ii. Prepare a group presentation explaining the purpose and characteristics of each design type.
iii. Discuss the suitability of each design for different Kenyan agro-ecological zones.
iv. Present findings to the class.
Assessor Observation Criteria:
Time: 3 Hours | Type: Pairs
Resources Required:
At a large-scale tea farm in Kericho, the agronomist conducts site assessments before constructing new storage facilities to ensure durability and compliance with environmental standards.
Tasks:
i. Visit a designated outdoor site within the college farm or nearby field.
ii. Measure and record soil pH and moisture content at three different points.
iii. Determine site orientation using a compass.
iv. Note environmental factors such as slope, drainage, and prevailing winds.
v. Prepare a brief report recommending design considerations based on findings.
Assessor Observation Criteria:
Time: 2 Hours | Type: Individual
Resources Required:
A TVET college in Eldoret plans to construct a poultry house and requires precise calculation of the floor area and wall volume for budgeting materials.
Tasks:
i. Using the provided farm structure plan, calculate the total floor area of the poultry house.
ii. Determine the volume of the walls given the height and thickness measurements.
iii. Calculate the volume of the roof if it is a gable design.
iv. Summarize all measurements in a tabulated format.
Assessor Observation Criteria:
Time: 3 Hours | Type: Individual
Resources Required:
At a cooperative farm in Thika, the farm manager requires a hand-drawn plan of a new irrigation water tank shed for approval by the farm's owners.
Tasks:
i. Draft a scaled plan of the irrigation water tank shed including walls, doors, and roof.
ii. Include dimensions and orientation on the plan.
iii. Indicate materials to be used for each component.
iv. Label all parts clearly.
Assessor Observation Criteria:
Time: 3 Hours | Type: Individual
Resources Required:
At a nursery in Nakuru, technical officers use CAD software to produce farm structure plans for extension services.
Tasks:
i. Open the CAD software and create a new drawing.
ii. Develop a plan for a small livestock shelter according to given dimensions.
iii. Include walls, doors, windows, and roof in the drawing.
iv. Add annotations and dimension lines accurately.
v. Save and print the drawing.
Assessor Observation Criteria:
Time: 1.5 Hours | Type: Group of 2
Resources Required:
At a hotel farm in Naivasha, management plans to build a storage shed and needs to select appropriate materials considering cost and durability.
Tasks:
i. Examine the provided material samples and specification sheets.
ii. Identify suitable materials for walls, roofing, flooring, and fencing.
iii. Discuss advantages and disadvantages of each material in the Kenyan climate.
iv. Prepare a recommendation chart for the hotel management.
Assessor Observation Criteria:
Time: 2 Hours | Type: Individual
Resources Required:
A retail business in Mombasa is constructing a cold storage facility and requires a detailed bill of quantities for budgeting and procurement.
Tasks:
i. Review the farm structure plan and identify all materials required for construction.
ii. Calculate quantities for each material using measurements from the plan.
iii. Use the rate handbook to estimate costs for materials and labour.
iv. Prepare a detailed bill of quantities listing items, quantities, unit costs, and totals.
Assessor Observation Criteria:
Time: 2 Hours | Type: Pairs
Resources Required:
At a feed mill in Kisii, planners must review farm structure designs submitted by farmers to ensure they meet safety and environmental guidelines.
Tasks:
i. Review the provided farm structure plans.
ii. Identify areas where the design complies or does not comply with safety and environmental regulations.
iii. Highlight non-compliant features and suggest corrective actions.
iv. Prepare a compliance report for the feed mill's management.
Assessor Observation Criteria:
Time: 1.5 Hours | Type: Group of 3
Resources Required:
At a dairy plant in Nairobi, students prepare awareness materials for smallholder farmers on why farm structure design matters for productivity and sustainability.
Tasks:
i. Research the importance of farm structure design focusing on cost savings, durability, and productivity.
ii. Develop a 10-minute presentation with visual aids.
iii. Present to the class simulating a farmer training session.
iv. Answer questions from the audience.
Assessor Observation Criteria:
Time: 2 Hours | Type: Individual
Resources Required:
At a piggery in Machakos, technicians need to measure existing farm structures to prepare renovation designs.
Tasks:
i. Select a farm structure on the college farm or nearby.
ii. Measure length, width, and height of the structure accurately.
iii. Use a spirit level to check the levelness of floors and walls.
iv. Record all measurements and prepare a scaled sketch.
Assessor Observation Criteria:
Time: 1.5 Hours | Type: Individual
Resources Required:
At a tea factory in Kericho, site engineers need to interpret construction plans to supervise farm structure projects effectively.
Tasks:
i. Review the given farm structure plans and specifications.
ii. Identify key design features including dimensions, materials, and special instructions.
iii. Highlight any ambiguous or unclear details.
iv. Prepare a summary report explaining the plan elements.
Assessor Observation Criteria:
Time: 2 Hours | Type: Individual
Resources Required:
At a rabbit unit in Nakuru, officers prepare maintenance schedules to extend farm structure lifespan and reduce repair costs.
Tasks:
i. Review sample maintenance records for farm structures.
ii. Identify key maintenance activities for walls, roofs, floors, and ventilation.
iii. Develop a maintenance schedule indicating frequency and responsible personnel.
iv. Write a brief report justifying the schedule.
Assessor Observation Criteria:
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