Lesson Notes By Weeks and Term v4 - SHS 3
≈SUBSTRUCTURE AND SUPERSTRUCTURE
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≈SUBSTRUCTURE AND SUPERSTRUCTURE
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Applied Technology
Class: SHS 3
Term: 1st Term
Week: 18
Grade code: 3.3.2.LI.3
Strand code: 3
Sub-strand code: 3
Content standard code: 3.3.2.CS.2
Indicator code: 3.3.2.LI.3
Theme: BUILDING CONSTRUCTION TECHNOLOGY
Subtheme: ≈SUBSTRUCTURE AND SUPERSTRUCTURE
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In Ghana, when we look at any finished building, from a simple family home in a village to a tall office block in Accra, the first thing we notice is its appearance. The surfaces of the walls are not left as rough sandcrete blocks. They are covered with various materials for beauty, protection, and hygiene. These coverings are called wall finishes. This lesson will explore the different types of wall finishes used in construction, why we choose one over another, and the tools and techniques required to apply them. Understanding wall finishes is crucial for anyone interested in building, design, or even just maintaining their own home effectively.
What is a Wall Finish? A wall finish is the final layer of material applied to the internal or external surface of a wall. It is what we see and touch in a completed building.
Purpose of Wall Finishes: Protection: To protect the structural wall (e.g., sandcrete blocks, concrete) from weather elements like rain, sun, and wind. Aesthetics (Beauty): To provide a decorative, visually appealing surface that enhances the look of the building. Durability: To provide a tough surface that can resist wear and tear, impact, and abrasion. Hygiene: To create a smooth, non-porous surface that is easy to clean and does not harbour dirt or germs. This is very important in kitchens, hospitals, and bathrooms. Impermeability: To prevent moisture from penetrating the wall.
Types of Wall Finishes
Here are some of the most common wall finishes you will see in Ghana. Plastering and Rendering This is often the first and most fundamental finish applied to blockwork. Plastering: The application of a sand-cement mortar mix to *internal* walls. Rendering: The application of a sand-cement mortar mix to *external* walls. Materials: Ordinary Portland Cement, sharp sand, and clean water. The typical mix ratio is 1 part cement to 3 or 4 parts sand (1:3 or 1:4). Sometimes, a plasticiser is added to make the mortar more workable. Process: Hacking: The wall surface is roughened to provide a good key (grip) for the mortar. Wetting: The wall is dampened to prevent it from sucking water from the mortar too quickly, which can cause cracking. Application: The mortar is applied to the wall using a hawk and a steel trowel. Screeding: A straight edge (screed batten) is used to level the mortar to a uniform thickness (usually 12-15mm). Floating: A wooden or plastic float is used to rub the surface, compacting the mortar and creating a smooth, even finish. Curing: The finished plaster/render is kept damp for several days (usually 7) by sprinkling water on it. This allows the cement to hydrate properly and gain maximum strength, preventing cracks. Painting This is the most popular decorative finish applied on top of plaster. Purpose: Provides colour, protects the plaster, and makes the surface easy to clean. Types of Paint: Emulsion Paint: Water-based. Used for interior walls and ceilings. It is breathable, has low odour, and dries quickly. Gloss/Oil Paint: Oil-based. Used for wood and metal surfaces (doors, window frames) and sometimes in kitchens and bathrooms because it is waterproof and very durable. It has a strong smell and takes longer to dry. Textured Paint (e.g., Trowel-on, Grafiato): A thick paint that creates a decorative textured finish. It is very durable and is often used on external walls to hide minor imperfections. Surface Preparation (Crucial!): The wall must be clean, dry, and smooth. Any cracks must be filled with putty or filler, and the surface sanded down. A primer or undercoat is often applied first to seal the surface and ensure the final paint colour is even. Tools: Paint brushes (for cutting in edges), rollers (for large flat areas), spray guns (for fast, professional application). Tiling Tiles are used in areas that require a waterproof, hygienic, and highly durable surface. Common Locations: Kitchen walls (splashbacks), bathroom walls, hospital operating rooms, and laboratory walls. Materials: Tiles: Ceramic (most common), Porcelain (stronger, less porous). Adhesive: Special tile cement or mortar to stick the tiles to the wall. Grout: A paste used to fill the gaps between the tiles. It comes in different colours. Tools: Notched trowel (to apply adhesive), tile cutter, spirit level, tile spacers. Process: The adhesive is spread on the wall, the tiles are pressed firmly in place using spacers for even gaps, and after the adhesive sets, the gaps are filled with grout. Wallpapers A decorative paper or vinyl material applied to walls with a special adhesive (paste). Advantages: Comes in countless patterns and textures, can hide minor wall defects. Disadvantages: Can be damaged by moisture (not suitable for bathrooms in Ghana unless it's special vinyl wallpaper), can be difficult to apply smoothly, and may peel in humid conditions. Common Use: Feature walls in living rooms, bedrooms, offices, and hotels. Cladding This involves fixing an outer layer of material to the wall. It is often done for decorative effect and extra protection. Types of Cladding Material: Stone Cladding: Thin slices of natural stone (like slate or sandstone) are fixed to the wall. It gives a prestigious, natural look. Seen on banks, hotels, and high-end houses. Wood Panelling (T&G): Tongue and Groove wooden boards are fixed to the wall, giving a warm, traditional feel. Aluminium Composite Panels (ACP): Modern, lightweight panels used on commercial buildings (e.g., banks, fuel stations). They are durable and come in many colours. P.O.P (Plaster of Paris) Screeding A very popular modern interior finish in Ghana. Material: A fine white powder (gypsum plaster) that is mixed with water to form a paste. Process: It is applied as a very thin, smooth layer over the initial sand-cement plaster. It gives a perfectly smooth, brilliant white finish that is ideal for painting. It is also used to create decorative cornices and ceiling designs.