1.1 Identification of Construction Material

Recognizing construction materials by their physical and chemical properties, sources, and typical applications enables professionals to select the right materials for specific building components. This understanding also aids in quality control and cost management on site.

1.1.1 walling materials

Walling materials provide the vertical enclosure of a building, offering structural support, security, and environmental protection. In Kenya, the choice of walling materials is influenced by availability, cost, climate, and intended building use.

Common Types of Walling Materials

• Concrete blocks: Widely used in urban and peri-urban areas for their strength and thermal mass, concrete blocks provide durability and ease of construction at a competitive cost.

stacked concrete blocks with hollow centers (Source: Wikimedia Commons)

• Bricks: Made from clay or concrete, bricks offer good compressive strength and aesthetic appeal, often used in both load-bearing and non-load-bearing walls.

• Stone: Natural stones such as granite and sandstone are used in regions where they are locally available, valued for their strength and natural appearance.

Stone paving floor under glass roof (Source: Wikimedia Commons)

• Timber: In rural and some urban contexts, timber is utilized for lightweight walling, especially for internal partitions or traditional housing.

• Interlocking blocks: These blocks reduce mortar use and speed up construction, increasingly popular in affordable housing projects across Kenya.

Properties Relevant to Walling Materials

• Compressive strength: Determines the load the wall can carry; essential for structural safety.
• Thermal insulation: Influences indoor comfort by reducing heat transfer, critical in Kenya’s varied climates.
• Durability: Resistance to weathering, pests, and chemical attack ensures longevity.
• Workability: Ease of cutting, shaping, and laying affects construction speed and quality.
• Moisture resistance: Prevents dampness and associated issues like mold and structural decay.

Selection Criteria in Kenyan Context

Selection depends on factors including local availability to reduce transport costs, compatibility with local climate conditions such as heavy rains or high temperatures, budget constraints, and the intended use of the building. For instance, concrete blocks are preferred in Nairobi’s urban environment for their strength, while stone may be favored in Kisii for its abundance.

1.1.2 roofing materials

Roofs protect buildings from weather elements and contribute to thermal comfort. The choice of roofing materials in Kenya must balance durability, cost, and ease of installation.

Types of Roofing Materials

• Corrugated iron sheets: Commonly used due to affordability and ease of installation, suitable for residential and commercial buildings.

corrugated iron sheet with brand marking (Source: Wikimedia Commons)

• Clay tiles: Offer good insulation and aesthetic appeal, often used in high-end residential projects.

Stacked clay roofing tiles (Source: Wikimedia Commons)

• Asbestos cement sheets: Previously popular but now discouraged due to health risks associated with asbestos fibers.

Workers installing asbestos cement roofing sheets (Source: Wikimedia Commons)

• Concrete roofing tiles: Durable and fire-resistant, increasingly used in public buildings and upscale housing.

Broken concrete roofing tiles pile (Source: Wikimedia Commons)

• Thatch: Traditional roofing made from grass or palm leaves, still used in rural areas for its natural insulation properties.

House with a thatched roof (Source: Wikimedia Commons)

• Fibre cement sheets: These are manufactured from a mixture of cement and cellulose fibers, offering resistance to rot and fire. In Kenya, fibre cement sheets are used in schools and hospitals due to their durability and low maintenance requirements, as seen in many public schools in Machakos County.

Performance Characteristics

• Waterproofing: Essential to prevent leaks and water damage.
• Thermal insulation: Influences energy efficiency and indoor comfort.
• Fire resistance: Important for safety, especially in densely populated areas.
• Weight: Affects roof structure design; heavy tiles require stronger support.
• Longevity: Determines maintenance frequency and replacement cycles.

Environmental and Economic Considerations

Sustainable roofing choices consider the environmental footprint of materials and their recyclability. For example, clay tiles made locally reduce carbon emissions from transport. Cost-effectiveness is critical in affordable housing projects, where corrugated iron sheets dominate.

1.1.3 clay and clay products

Clay is a natural material widely used in construction for its plasticity and strength after firing. Its products are integral to traditional and modern building techniques in Kenya.

Types of Clay Products

• Bricks: Fired clay bricks are durable and widely used for walls and foundations.
• Tiles: Clay tiles are used for roofing and flooring due to their hardness and decorative appeal.

Four square ceramic tiles arranged in a grid (Source: Wikimedia Commons)

• Earthenware pipes: Used in drainage systems, offering resistance to chemicals and abrasion.

• Terracotta: Employed for decorative architectural features.

• Clay plaster: Provides a breathable finish that regulates indoor humidity.

Properties of Clay Products

• Plasticity before firing: Allows shaping into various forms.
• Hardness after firing: Provides structural strength.
• Porosity: Influences water absorption and insulation.
• Thermal mass: Helps regulate indoor temperature by absorbing and releasing heat.
• Chemical resistance: Important for durability in various environments.

Challenges and Solutions in Use

Clay products may be susceptible to cracking or moisture damage if not properly manufactured or installed. Kiln-fired bricks with controlled firing temperatures improve quality. Application of protective coatings or proper detailing can reduce moisture ingress.

1.1.4 class and class products

Glass is a versatile material used in construction for transparency, light transmission, and aesthetic enhancement. In Kenyan buildings, glass supports daylighting and architectural expression.

Types of Glass Used in Construction

• Float glass: Standard flat glass used in windows and facades.

• Tempered glass: Heat-treated for enhanced strength and safety.

• Laminated glass: Consists of layers bonded with plastic for safety and sound insulation.

Laminated glass art panel in building interior (Source: Wikimedia Commons)

• Insulated glass units (IGUs): Double or triple glazed for improved thermal performance.

• Textured glass: Provides privacy while allowing light transmission.

• Wired glass: This type of glass contains a wire mesh embedded within, providing enhanced fire resistance and safety. Wired glass is often used in stairwells and fire exits in commercial buildings in Nairobi, such as those regulated under the Building Code of Kenya.

Windows with wired glass panes (Source: Wikimedia Commons)

Properties Relevant to Building Use

• Transparency: Facilitates natural lighting.
• Thermal insulation: IGUs reduce heat gain or loss, improving energy efficiency.
• Safety: Tempered and laminated glass reduce injury risk upon breakage.
• Acoustic insulation: Laminated glass dampens noise, beneficial in urban settings.
• UV resistance: Protects interiors from fading due to sunlight.

Applications in Kenyan Buildings

Glass is widely used in offices, shopping malls, and modern residential buildings. For example, county government offices in Nairobi incorporate IGUs to reduce energy costs associated with air conditioning.

1.1.5 timber and timber products

Timber remains a fundamental construction material in Kenya, valued for its availability, workability, and aesthetic qualities. It is used in framing, flooring, and finishes.

Types of Timber Used

• Softwoods: Such as pine, used for framing and light construction.

Stacks of softwood logs for carpentry (Source: Wikimedia Commons)

• Hardwoods: Including mahogany and teak, preferred for furniture and finishes due to durability.
• Engineered timber: Products like plywood and laminated veneer lumber (LVL) offer enhanced strength and stability.

Engineered timber bridge structure (Source: Wikimedia Commons)

• Treated timber: Chemically treated to resist pests and decay.

• Composite timber: Made from wood fibers and plastics, used for decking and cladding.

• Bamboo: Increasingly used as a sustainable timber alternative, bamboo grows rapidly and is harvested for lightweight construction and scaffolding. In Kenya, organizations such as the Kenya Forestry Research Institute (KEFRI) promote bamboo for eco-friendly housing and furniture.

• Cypress: Cypress is a popular softwood in Kenya, valued for its straight grain and resistance to termites. It is commonly used for roofing trusses and door frames, especially in residential developments in Nakuru.

Properties Impacting Use

• Strength and stiffness: Critical for structural applications.
• Durability: Influenced by species and treatment, affecting lifespan.
• Workability: Ease of cutting, nailing, and shaping.
• Moisture content: Affects dimensional stability and susceptibility to rot.
• Aesthetic appeal: Grain and color influence design choices.

Preservation and Maintenance

Timber in Kenya often requires treatment to protect against termites and fungal decay, particularly in humid regions such as Kisumu. Regular maintenance, including painting and sealing, extends service life.

1.1.6 reinforcing materials

Reinforcing materials enhance the strength and ductility of concrete and masonry, enabling the construction of durable and safe structures.

Common Reinforcing Materials

• Steel reinforcement bars (rebar): High tensile strength bars embedded in concrete to resist tension.
• Welded wire mesh: Prefabricated steel mesh used in slabs and walls.
• Fiber reinforcement: Synthetic or natural fibers added to concrete to improve crack resistance.
• Composite reinforcement: Materials like fiberglass bars offering corrosion resistance.
• Prestressing tendons: High-strength steel cables used in prestressed concrete elements.

Properties and Functions

• Tensile strength: Reinforcement compensates for concrete’s low tensile capacity.
• Bonding: Good adhesion between reinforcement and concrete ensures load transfer.
• Ductility: Allows structures to deform under stress without sudden failure.
• Corrosion resistance: Essential for durability, particularly in Kenya’s coastal regions.
• Flexibility: Some reinforcement types allow for curved or complex shapes.

Application Considerations

Proper placement and cover of reinforcement bars are critical to prevent corrosion and ensure structural integrity. At Nairobi County Hospital, strict adherence to reinforcement detailing has prevented premature concrete failures.

1.1.7 finishing materials

Finishing materials provide the final surface treatment to walls, floors, and ceilings, enhancing aesthetics and durability.

Types of Finishing Materials

• Plaster: Cement or lime-based coatings that smooth and protect wall surfaces.
• Paints: Provide color, protection against moisture, and resistance to weathering.
• Tiles: Ceramic or porcelain tiles used for floors and walls, offering durability and easy maintenance.
• Wall cladding: Materials such as wood, stone veneer, or PVC panels for decorative and protective purposes.

• Flooring finishes: Materials including vinyl, laminate, and polished concrete.

• Varnishes: Varnishes are transparent or tinted finishes applied to wood surfaces to protect them from moisture and enhance their natural beauty. In Kenyan office buildings, varnished mahogany is often used for executive doors and trim, providing both durability and a high-quality appearance.

Properties Affecting Performance

• Adhesion: Ability to bond to substrate affects durability.
• Water resistance: Prevents damage in wet areas.
• Wear resistance: Important for high-traffic surfaces.
• Aesthetic qualities: Color, texture, and reflectivity influence environment ambiance.
• Maintenance requirements: Determines lifecycle costs.

Selection Factors in Kenya

Finishing material choice reflects building function, local climate, and budget. For example, ceramic tiles are common in Kenyan hotels for their ease of cleaning and durability under heavy foot traffic.

1.1.8 roofing materials

Beyond the main roof coverings, a roof also needs modern pre-finished sheets, translucent sheets, underlays, accessories and fixings, and a technician must be able to identify each one and check its quality on delivery. Many roof failures in Kenya come not from the covering itself but from thin sheets, wrong fixings or missing accessories, so correct identification protects the client's money and the building. In practice, materials are identified by their profile, thickness (gauge), coating, colour, markings and the supplier's documents, and checked against the specification before use. Example: when roofing a milk cooling shed for a dairy farm in Ol Kalou, the site supervisor measured sample sheets with a vernier calliper and rejected a consignment marked gauge 28 that measured nearer gauge 32, saving the farm from a roof that would have dented and rusted early.

Name	Specification	Use
Pre-painted box profile sheets	Galvanised or aluzinc-coated steel, factory painted, commonly gauge 28 to 30 (about 0.4 mm to 0.3 mm), trapezoidal ribs	Durable, attractive roofing for houses, schools and commercial buildings
Stone-coated steel tiles	Steel panels coated with acrylic and granules, shaped like tiles	Light roofs with a tiled appearance, suitable for steep pitches
Aluminium roofing sheets	Aluminium alloy, corrosion resistant	Roofs in coastal and industrial areas where steel would rust
Polycarbonate (translucent) sheets	Clear or tinted plastic sheets matching common profiles	Letting daylight into workshops, verandas and greenhouses
Roofing underlay (felt or membrane)	Bitumen felt or breathable synthetic membrane in rolls	Second line of waterproofing and condensation control under sheets and tiles
Ridge caps and flashings	Matching steel, aluminium or clay pieces	Sealing ridges, hips, valleys and junctions with walls
Gutters and downpipes	PVC, galvanised steel or aluminium sections	Collecting and draining rainwater from the roof
Roofing fixings	Self-drilling screws or roofing nails with sealing washers	Fixing sheets securely to purlins without leaks

Checks When Identifying Roofing Sheets on Site

• Thickness (gauge): Measure the sheet with a vernier calliper or micrometer, since a lower gauge number means a thicker, stronger sheet, and thin sheets dent and corrode quickly.
• Coating type: Check the label or markings for galvanised (zinc) or aluzinc (aluminium-zinc) coating, as aluzinc generally resists corrosion longer.
• Standards mark: Look for the KEBS standardisation mark and the manufacturer's name printed on the sheet.
• Profile and cover width: Confirm the profile matches the specification and the effective cover width used in quantity calculations.
• Paint and finish: Check that painted sheets have an even colour without scratches, peeling or rust spots.
• Length and squareness: Measure sheet lengths and check that ends are cut square, so sheets align and overlap correctly.

Calculating the Number of Roofing Sheets per Row

Example: one side of a roof for a SACCO office in Embu is 9.0 m long, and box profile sheets give an effective cover width of 0.9 m.

Number of sheets = Length of roof ÷ Effective cover width

Number of sheets = 9.0 m ÷ 0.9 m

Number of sheets = 10 sheets per row

1.1.9 finishing materials

In addition to plaster, paint, tiles and claddings, buildings use other finishing materials for ceilings, joints, edges and decorative surfaces, which must be identified correctly to achieve the required quality and appearance. Using the wrong type, such as interior paint outside or ordinary gypsum board in a wet kitchen, leads to early failure and costly redecoration. In practice, finishing materials are identified by their composition, labels, thickness, size, colour codes and intended use, and checked against the finishes schedule on the drawings. Example: for the guest rooms of a hotel in Nanyuki, the contractor checked every delivery of gypsum boards, cornices and paints against the finishes schedule, and returned a batch of standard boards delivered for the bathrooms where moisture-resistant boards were specified.

Other Finishing Materials

• Gypsum ceiling and partition boards: Smooth boards of gypsum between paper facings, usually 9 mm to 12.5 mm thick, used for ceilings and partitions, with moisture-resistant types for wet areas.
• PVC ceiling panels: Light, washable plastic panels that need no painting, used in kitchens, bathrooms and offices.
• Timber ceiling finishes: Tongue and groove boards and timber-based boards that give a natural, warm appearance.
• Cornices and skirtings: Decorative strips of gypsum, timber, PVC or tile that finish junctions between walls and ceilings or floors.
• Terrazzo: A finish of marble chips set in cement and ground smooth, used for durable, attractive floors in public buildings.
• Wallpaper and wall coverings: Paper, vinyl or fabric sheets glued to walls for decoration and easy cleaning.
• Sealants and fillers: Silicone, acrylic and polyurethane sealants and wall fillers used to close joints and gaps before painting or around fittings.
• Wood stains and preservatives: Coloured or clear liquids that protect timber and change its colour while showing the grain.

Checks When Identifying Finishing Materials

• Read labels and data sheets: Confirm the product name, type (interior or exterior, water-based or oil-based) and intended use.
• Check batch numbers and colour codes: Use materials from the same batch on one area so that colour and texture match.
• Measure sizes and thicknesses: Check board thickness, tile sizes and panel dimensions against the specification.
• Inspect for damage: Reject broken tiles, chipped boards, dented tins and products past their expiry date.
• Confirm suitability for location: Check that materials for wet areas, outdoor walls or heavy traffic are rated for those conditions.

1.1.10 binding materials

Binding materials hold construction components together, providing cohesion and strength in masonry and concrete.

Common Binding Materials

• Cement: The primary hydraulic binder, cement reacts with water to form a hard matrix.
• Lime: Used historically and in some modern mortars for flexibility and breathability.
• Gypsum: Sets quickly and is used in plaster and drywall.
• Clay: Acts as a binder in traditional mud bricks.
• Admixtures: Chemical additives that modify setting time and strength.

Properties of Binding Materials

• Setting time: Influences workability and construction speed.
• Strength development: Determines load-bearing capacity of masonry.
• Durability: Resistance to environmental degradation.
• Workability: Ease of mixing and applying.
• Compatibility: Must bond well with aggregates and reinforcement.

Quality Control and Testing

In Kenyan construction sites, cement quality testing includes fineness, setting time, and compressive strength to ensure compliance with standards such as those set by KEBS.

1.1.11 Glass and glass products

Besides glazing glass for windows and facades, the construction industry uses many other glass products, including glass blocks, mirrors, glass louvres, glass mosaic and glass fibre insulation, each identified by its form, thickness, markings and use. Correct identification matters because safety glass, for example, must be used in doors, low windows and balustrades, and substituting ordinary glass can cause serious injuries when it breaks. In practice, glass is identified by measuring thickness, examining the edges and surface, checking permanent safety marks, and confirming the supplier's documents. Example: before fitting glass doors in a bank branch in Nakuru, the site supervisor checked that every panel carried the toughened glass mark etched in one corner, and rejected two panels without it.

Other Glass Products Used in Buildings

• Glass blocks: Hollow glass units laid like masonry to form walls and panels that let in light while giving privacy.
• Mirrors: Float glass with a reflective silver coating and protective backing, used in bathrooms, gyms and for decoration.
• Glass louvre blades: Narrow strips of glass, usually 4 mm to 6 mm thick, fitted in adjustable louvre frames for ventilation and light.
• Tinted and reflective glass: Glass coloured or coated to reduce glare and solar heat gain in offices and hot climates.
• Frosted and obscure glass: Glass with a sandblasted, acid-etched or patterned surface that diffuses light for privacy in bathrooms and offices.
• Glass mosaic tiles: Small coloured glass tiles used for decorative walls, swimming pools and splashbacks.
• Glass wool and glass fibre: Fibrous glass products used for thermal and acoustic insulation in roofs and partitions, and glass fibre for reinforcing plastics and some cement products.

Identifying Glass on Site

• Measure the thickness: Use a vernier calliper to check glass thickness, commonly 3 mm, 4 mm, 5 mm or 6 mm for windows, against the specification.
• Look for safety marks: Toughened glass usually carries a permanent etched mark in a corner, and laminated glass shows a plastic interlayer when the edge is viewed.
• Examine the edges: Laminated glass edges show two or more glass layers bonded together, and insulated units show a spacer bar between panes.
• Check surface finish: Patterned, frosted, tinted and reflective glass can be recognised by their texture, colour or mirror-like appearance.
• Check for wire mesh: Wired glass shows a visible wire grid inside the pane.
• Inspect for defects: Reject glass with cracks, chips, scratches, bubbles or distortion that will be visible or weaken the pane.

1.1.12 Bitumen and bituminous products

Bitumen is a viscous material used mainly for waterproofing and road construction, with applications in building foundations and roofing.

Types of Bituminous Products

• Bitumen sheets: Used as damp-proof membranes beneath concrete slabs.
• Bituminous paints: Protective coatings for metal and concrete surfaces.
• Emulsified bitumen: Used in road surfacing and waterproofing.
• Oxidized bitumen: Harder grade for roofing felt and paving.
• Cutback bitumen: Bitumen dissolved in solvent for easier application.

Properties and Functions

• Waterproofing: Prevents water ingress in foundations and roofs.
• Adhesion: Bonds well to substrates to form continuous membranes.
• Flexibility: Accommodates structural movements without cracking.
• Durability: Resistant to weathering and chemical attack.
• Thermal stability: Maintains properties across Kenya’s temperature range.

Applications in Kenyan Construction

County government offices in Mombasa use bituminous membranes extensively to protect basements from groundwater. Proper application techniques ensure effective waterproofing.

Chapter Summary

This chapter provides a comprehensive overview of essential construction materials, beginning with the identification of various walling materials that form the structural envelopes of buildings. It then explores roofing materials, highlighting their role in protecting structures from weather elements. The discussion extends to clay and clay products, emphasizing their traditional and modern applications in construction. Glass and its products are examined for their aesthetic and functional contributions, while timber and timber products are addressed for their versatility and strength. Reinforcing materials are introduced to explain their importance in enhancing structural integrity. The chapter also covers finishing materials that provide both protection and visual appeal to surfaces. Finally, binding materials and bitumen with its related products are discussed for their critical roles in joining components and waterproofing, respectively.

Am I competent?

At the start of this chapter we promised you would be able to:

• Identify different construction materials by understanding their unique properties.
• Recognize the essential materials needed for various types of construction projects.
• Assemble construction materials, tools, and equipment correctly according to the construction methods.
• Prepare construction materials properly to suit their intended purpose.
• Use construction materials accurately and safely following the correct construction process.

Tick each one you can genuinely do.

So, are you there yet?

You're competent when you can confidently do 50% or more of what this chapter promised.

Sign in to record how you're doing.