4.1 Types of interior materials

Interior materials are the products used to finish, furnish, equip and light the inside of buildings, including floor finishes, ceilings, wall finishes, doors and windows, acoustic products, furniture, lighting and soft furnishings. The choice of material affects how a space looks and feels, how long it lasts, how easy it is to clean and maintain, how safe it is, and how much it costs. An interior designer must know the main types of materials, their characteristics and where each is best used, so that every space meets the client's functional and aesthetic needs within budget. Example: in designing a children's ward for a private hospital, the designer selects seamless vinyl flooring for hygiene, washable paint for walls, mineral fibre ceiling tiles for quietness and brightly coloured, wipeable upholstery for furniture.

4.1.1 Flooring materials

Flooring materials form the walking surface of a space and must withstand foot traffic, furniture loads, cleaning and spills while contributing to the room's appearance and comfort. Selection depends on the use of the space, level of traffic, moisture, maintenance and budget. Example: a supermarket chooses porcelain tiles for its shopping floor because they resist heavy trolley traffic and are easy to mop.

Worked example: estimating floor tiles

A room measures 4.5 m × 3.6 m and will be tiled with 600 mm × 600 mm porcelain tiles, allowing 10% for cutting and breakage.

Floor area = 4.5 × 3.6 = 16.2 m²

Area of one tile = 0.6 × 0.6 = 0.36 m²

Number of tiles = 16.2 ÷ 0.36 = 45 tiles

Tiles with wastage = 45 + (10% × 45) = 45 + 4.5 = 49.5

Answer: 50 tiles

4.1.2 Ceiling materials

Ceiling materials finish the overhead surface of a room, hide structure and services, and support lighting, ventilation and acoustic needs. Ceilings may be fixed directly to the structure or suspended on a frame below it to create space for cables and ducts. Example: an insurance company's open-plan office uses a suspended grid ceiling with removable mineral fibre tiles so technicians can reach cables above.

4.1.3 Walling materials

Walling materials include the materials used to build interior partitions and the finishes applied to wall surfaces. Walls divide spaces, provide privacy and display much of a room's colour and character, so their materials must suit both function and appearance. Example: a law firm uses glass partitions for meeting rooms to keep the office bright while giving acoustic privacy, and timber panelling in the reception for a prestigious look.

Partition materials

• Masonry blocks and bricks: Solid, durable partitions with good sound insulation, common in Kenyan buildings.
• Drywall (gypsum on metal studs): Lightweight, quick-to-build partitions that allow cables inside the wall.
• Glass partitions: Toughened or laminated glass in frames, allowing light and visibility.
• Timber stud partitions: Timber frames clad with boards, used for light internal walls.
• Demountable partitions: Prefabricated panels that can be moved when layouts change.

Wall finishes

Worked example: estimating paint quantity

Four walls of a room each measure 4 m × 2.8 m. A door of 2 m² and a window of 2.4 m² are not painted. The paint covers 10 m² per litre per coat, and two coats are needed.

Total wall area = 4 × (4 × 2.8) = 4 × 11.2 = 44.8 m²

Area to paint = 44.8 − (2 + 2.4) = 40.4 m²

Paint needed = (40.4 × 2) ÷ 10 = 80.8 ÷ 10 = 8.08 litres

Answer: about 8 litres, so two 4-litre tins plus a little extra, or one 10-litre tin

4.1.4 Windows and doors materials

Windows and doors control access, light, ventilation, security and privacy, and their frames, leaves and glazing are made from a range of materials. The choice affects durability, security, maintenance, insulation and appearance. Example: a hotel in a coastal town specifies uPVC window frames because they do not rust or rot in the humid, salty air.

Frame materials

Glazing materials

• Clear float glass: Standard transparent glass for ordinary windows.
• Toughened (tempered) glass: Heat-treated safety glass that breaks into small blunt pieces, used in doors and partitions.
• Laminated glass: Layers bonded with a plastic interlayer that holds broken glass together, used for security and safety.
• Frosted and patterned glass: Obscured glass that gives privacy, used in bathrooms and offices.
• Tinted and reflective glass: Reduces glare and heat from the sun.
• Double glazing: Two panes with a gap between them, improving heat and sound insulation.

Door types by material

• Solid timber doors: Heavy, durable and good at reducing sound.
• Flush doors: Plain flat doors made of a frame and facing boards, hollow or solid core.
• Panel doors: Doors with raised or flat panels within a frame, traditional in appearance.
• Glass doors: Toughened glass doors that keep spaces open and bright.
• Steel security doors: Strong doors for entrances, stores and server rooms.
• Fire-rated doors: Doors built and tested to resist fire for a set time, used in escape routes.

4.1.5 Acoustic materials

Acoustic materials control sound within a space and between spaces, either by absorbing sound to reduce echo, by blocking sound from passing through walls and floors, or by scattering sound evenly. They are important in offices, classrooms, conference rooms, hospitals, places of worship and entertainment spaces. Example: a radio station lines its studios with fabric-wrapped acoustic panels and fits heavy, sealed doors to stop noise from corridors.

Sound-absorbing materials

• Acoustic wall panels: Fabric-wrapped mineral wool or fibre panels fixed to walls to reduce echo.
• Acoustic ceiling tiles: Porous mineral fibre or perforated tiles that absorb sound overhead.
• Acoustic foam: Lightweight, profiled foam used in studios and media rooms.
• Perforated timber or metal panels: Decorative panels with holes backed by absorbent material.
• Wood wool panels: Panels of wood fibres bound with cement, durable and sound-absorbing.
• Carpets, curtains and upholstery: Soft furnishings that absorb sound in everyday interiors.

Sound-insulating materials

• Mineral wool insulation: Placed inside partitions and ceilings to reduce sound passing through.
• Mass-loaded vinyl: Heavy, flexible sheet added to walls and floors to block sound.
• Double-layer plasterboard: Extra layers of board increase the mass of partitions.
• Acoustic seals: Seals around doors and windows prevent sound leaking through gaps.
• Resilient underlays: Layers under floors that reduce impact noise from footsteps.

Sound-diffusing materials

• Diffuser panels: Shaped timber or plastic panels that scatter sound evenly in studios and auditoria.
• Irregular surfaces: Bookshelves and textured walls that break up sound reflections.

4.1.6 Furniture and fixtures

Furniture includes movable items such as chairs, tables, beds and cabinets, while fixtures are items permanently attached to the building, such as built-in cupboards, counters, vanities and sanitary fittings. Furniture and fixtures are made from a wide range of materials chosen for strength, appearance, comfort, cost and ease of cleaning. Example: a café uses solid hardwood tables with steel frames, moisture-resistant board for built-in counters and quartz worktops for durability and hygiene.

4.1.7 Lighting materials

Lighting materials include the light sources (lamps) and the materials used to make light fittings (luminaires), such as housings, diffusers, reflectors and shades. They determine how much light is produced, its colour and quality, how it is spread and how the fittings look in the space. Example: a boutique hotel uses LED downlights with aluminium housings for general light and woven rattan pendant shades over the dining tables for a warm, local character.

Light sources

Luminaire materials

• Aluminium and steel housings: Durable bodies that hold lamps and help dissipate heat.
• Opal acrylic and polycarbonate diffusers: Spread light evenly and reduce glare.
• Glass: Clear, frosted or coloured glass shades and diffusers for decorative fittings.
• Reflectors: Polished metal surfaces that direct light where it is needed.
• Fabric and paper shades: Soften light in table lamps and pendants.
• Natural materials: Rattan, wood, sisal and bamboo shades that add texture and local character.
• Brass and copper: Decorative metal finishes for feature fittings.

4.1.8 Furnishing materials

Furnishing materials are the soft materials used in curtains, blinds, upholstery, cushions, bedding, rugs and decorative textiles. They add colour, texture, comfort and warmth to interiors and help control light, privacy and sound. Choice depends on the use of the item, durability needed, cleaning requirements, sunlight exposure and appearance. Example: a conference centre chooses heavy-duty polyester upholstery for chairs because it resists wear and stains, and blackout-lined curtains for its presentation halls.

Fabrics

Other furnishing materials

• Blinds: Roller blinds in fabric or blackout material, Venetian blinds in aluminium or timber, and vertical blinds in PVC or fabric.
• Rugs and mats: Woven wool, cotton, jute and sisal rugs that define areas and add warmth.
• Cushion and seat fillings: Foam, polyester fibre and feather fillings for comfort and support.
• Linings and interlinings: Fabrics behind curtains that protect from sunlight, add body and block light.
• Trimmings: Braids, tassels, fringes and piping that decorate soft furnishings.