Chapter 3: Construct farm structures

Constructing farm structures is a fundamental skill for Agriculture and Extension professionals tasked with improving farm productivity and sustainability in Kenya. Proper construction ensures that farm structures such as storage units, animal shelters, and irrigation facilities are durable, functional, and suited to local environmental conditions. This chapter equips learners with the knowledge of essential terminology, criteria for selecting suitable sites, and the tools and equipment necessary for effective farm structure construction. Mastery of these topics enhances the ability to advise farmers and implement projects that optimize resource use and safeguard farm assets.

3.1 Farm structure construction

Farm structure construction is the building of the physical installations a farm needs, such as animal houses, stores, water tanks, fences and greenhouses. It follows the farm plan and the structure design and turns them into a finished building on the ground. The work moves in a set order: the site is chosen and investigated, the structure is set out, the foundation is laid, the walls or frame and roof are built, and the finishes are added. A technician who understands the terms, the choice of site and the tools can supervise this work on a farm and advise a farmer on what is required at each stage.

3.1.1 Definition of terms

Builders, farmers and technicians must use the same words for the same things, otherwise instructions are misunderstood and work is done wrongly. The terms below are used throughout the construction stages.

Farm structure

A farm structure is a permanent or semi-permanent construction that supports farm work, such as storing produce, housing livestock or holding water. A granary that protects harvested maize from rain, rodents and insects is a farm structure.

Construction

Construction is the whole process of putting a structure together on site, from clearing and marking the ground to the finished structure ready for use.

Site selection

Site selection is the process of choosing the right piece of ground for a structure after considering the ground, the surroundings and the access. A well-drained site near the farmstead is preferred for a dairy shed.

Setting out

Setting out is the marking on the ground of the position, outline and levels of a structure from the drawing, using pegs, string lines and a measuring tape. It makes sure the building goes where it was designed.

Foundation

The foundation is the base of a structure. It spreads the weight of the building over the ground, holds the structure steady and resists settling and moisture. A concrete foundation keeps a poultry house level and stops damp from rising into the walls.

Load-bearing elements

Load-bearing elements are the columns, beams and walls that carry the weight of the roof and the building and pass it down to the foundation. In a farm store, timber or steel posts and roof beams carry the roof and protect the stored produce.

Superstructure

The superstructure is the part of the structure above the foundation level, namely the walls or frame, the roof and the finishes.

Building materials

Building materials are the raw materials used in construction, such as timber, stone, bricks and blocks, cement, sand, ballast, steel bars, iron sheets and thatch. They are chosen for availability, cost, strength and suitability to the farm environment. Locally available timber, for example, may be used for the posts of a livestock fence.

Concrete

Concrete is a hardened mixture of cement, sand, ballast and water. It is used for foundations, floors, troughs and tank bases because it is strong in compression and does not rot.

3.1.2 Site selection

The farm plan chooses the general area for a structure from a whole-farm view. Site selection at construction stage asks a narrower question: can this exact spot carry and serve this structure? The location affects the cost of the foundation, how long the building lasts, the risk of damage and how easy it is to use and maintain. The checks below are made on the ground before work starts.

Ground conditions and soil stability

Sites with firm, well-drained soil cause fewer foundation problems such as sinking and cracking. Sandy loam and murram are generally suitable, while clay soils may need special foundation treatment and expansive black cotton soils may need the foundation to be taken below the layer that moves. A trial pit dug at the site, as in the site investigation steps below, shows the soil layers and the depth to firm ground.

Topography and drainage

Flat or gently sloping land is preferred because water runs off and the cost of levelling is small. A water tank is not placed on an unstable slope, since a leak can wash out the ground beneath it. Low places and valley floors that collect water are avoided.

Accessibility

The site must be reachable by the vehicles that will bring materials and later use the structure. A storage shed near the main entrance, for example, shortens the time spent moving produce in and out.

Proximity to water and services

Structures such as irrigation pumps, livestock troughs and poultry houses are placed near a reliable water point to reduce the labour of carrying water. Water for mixing concrete and mortar is also needed on site during building, and so is a place to stack materials.

Environmental hazards

Flood-prone ground, exposed high ground and places close to thick bush that shelters pests and wild animals are avoided, since they cause damage and losses. Large trees near a building are checked because their roots can lift floors and their branches can fall on roofs.

Sunlight, orientation and ventilation

A structure is orientated to give good natural light and airflow, as set out when farm conditions are analysed in the farm plan. At site level, check that no tree, wall or neighbouring building blocks the openings.

Land tenure and approvals

The farmer must have secure rights to the land before building, and the structure may need approval from the authorities that regulate building and land use in the area. An extension officer advises the farmer to check what is required before work starts.

Steps in a site investigation

1. Walk the proposed area with the farmer and note the slope, drainage lines, existing structures, trees and services.
2. Check access for delivery vehicles and the route for water and power.
3. Dig a trial pit at the proposed position and record the soil layers and any water that seeps in.
4. Observe where runoff flows during rain, or ask the farmer about flooding in past seasons.
5. Compare the choices on the farm and choose the one that meets the most requirements at the least cost.
6. Peg the corners of the chosen site and mark the access route.
7. Record the decision and the reasons so that the farmer can refer to them later.

3.1.3 Farm structure tools and equipment

Constructing farm structures needs tools for measuring, digging, mixing, cutting and fixing. Choosing the right tool and keeping it in good order improves the quality of the work and reduces accidents. The common tools are summarised below.

3.1.3.1 Uses of farm structures tools and equipment

Each tool belongs to a stage of the work, and using it properly gives a straight, level and strong structure.

• Setting out and measuring: The tape measures the outline, the pegs and string mark it, and the builder checks that the corners are square by comparing the two diagonals, which must be equal. A spirit level and plumb bob are used on foundations, walls and posts to keep them horizontal and upright.
• Excavation: The pickaxe loosens hard ground and the shovel throws out the loose soil when digging trenches, post holes and pits. The trench is dug to the depth and width on the drawing and its bottom is levelled.
• Mixing and placing concrete: The concrete mixer, or a shovel and a clean mixing platform where there is no mixer, mixes cement, sand, ballast and water to a uniform colour. The wheelbarrow carries the mix to the foundation or floor.
• Masonry: The trowel lays mortar and shapes joints, and the spirit level checks each course of blocks or bricks.
• Timber work: The handsaw cuts timber to length and the claw hammer drives the nails that fix posts, rafters and purlins.
• Handling materials: The wheelbarrow and the shovel move sand, ballast, blocks and water around the site so that workers do not carry loads by hand.

All workers wear gloves and boots while working, and dust masks and eye protection when cutting or mixing cement. Proper training in tool handling reduces injuries and improves the quality of construction.

3.1.3.2 Maintenance of farm structures tools and equipment

Tools that are looked after last longer, work better and are safer. They are cleaned after use, inspected before use and stored in a dry place.

• Measuring tapes: Wind the tape in carefully so that it does not kink, and wipe off soil and cement so that the markings stay readable and accurate.
• Spirit levels: Check the level before use by placing it on a flat surface, reading it, then turning it end to end and reading it again. The two readings must agree, otherwise the vial is replaced.
• Shovels, pickaxes and hammers: Inspect handles for cracks and heads for looseness or wear, and replace damaged handles at once, because a head that flies off causes serious injury.
• Handsaws: Sharpen them regularly, wipe them dry and store them with a light coat of oil to prevent rust.
• Trowels: Wash off mortar after each use and dry the blade, since hardened cement ruins the edge.
• Concrete mixers: Wash out the drum immediately after use so that cement does not harden inside, grease the moving parts and check the engine oil and belts as the maker advises.
• Wheelbarrows: Keep the tyre inflated to the correct pressure, grease the axle bearings and clean the tray after each job.
• Storage: Hang tools on racks in a dry store and lock it at night, which also protects them from theft.

Chapter Summary

This chapter explored the construction of farm structures, beginning with the clarification of key terms related to the subject to establish a clear understanding of the concepts involved. The importance of careful site selection was emphasized, highlighting factors that influence the suitability of a location for building durable and functional farm structures. An overview of the essential tools and equipment used in the construction process was provided, detailing their specific roles in various farm structure assignments. The chapter also covered the proper maintenance of these tools and equipment to ensure their longevity and effectiveness. Moving forward, the chapter addressed the principles of designing farm structures, focusing on creating plans that meet the practical needs of the farm while considering environmental and resource factors. Through this comprehensive approach, the chapter equipped students with foundational knowledge and practical skills for successful farm structure construction and design.