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: 20
Grade code: 3.3.2.LI.5
Strand code: 3
Sub-strand code: 3
Content standard code: 3.3.2.CS.2
Indicator code: 3.3.2.LI.5
Theme: BUILDING CONSTRUCTION TECHNOLOGY
Subtheme: ≈SUBSTRUCTURE AND SUPERSTRUCTURE
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This lesson introduces learners to the various types of finishes applied to ceilings in Ghanaian buildings. The ceiling is a critical part of the superstructure that not only hides the roof structure and services (like electrical wiring) but also contributes significantly to the beauty, comfort, and function of a room. Understanding different ceiling finishes, their applications, and installation methods is essential for any student of building technology, whether they aim to be an artisan, a site supervisor, or a designer.
Introduction: What is a Ceiling and Why Do We Finish It?
A ceiling is the overhead interior surface that covers the upper limits of a room. In many buildings, it is attached to ceiling joists, which are part of the roof or floor structure above.
Purposes of a Ceiling Finish: Aesthetics: To provide a clean, smooth, and visually pleasing surface. It completes the look of a room. Concealment: To hide the structural elements like trusses, joists, and services such as electrical wiring, plumbing pipes, and HVAC ducts. Insulation: To provide thermal insulation (keeping the room cool) and acoustic insulation (reducing noise). Fire Resistance: Certain ceiling materials can help slow the spread of fire. Light Reflection: A light-coloured, smooth ceiling reflects more light, making the room brighter and potentially saving energy. Types of Ceiling Finishes Used in Ghana
Here we will discuss the materials mentioned in the NaCCA exemplars, which are very common in our local context. Plywood Ceiling Description: This involves fixing large sheets of plywood directly to the underside of the ceiling joists. The joints between the sheets are often covered with small timber strips called "cover strips" or "h-profiles". Common Local Timber for Plywood: Wawa, Ceiba. Characteristics: Relatively inexpensive and quick to install. Lightweight. Can be painted or varnished. Advantages: Cost-effective: Often the cheapest option for a board ceiling. Availability: Plywood is widely available in all major towns in Ghana. Speed of Installation: Large sheets cover a wide area quickly. Disadvantages: Susceptible to moisture: Can sag, delaminate (layers peel apart), or get mouldy in damp areas like bathrooms or kitchens. Termite Attacks: Can be attacked by termites if not properly treated. Aesthetics: Often considered less modern or premium compared to other finishes. The visible joints and cover strips can look busy. Timber Tongue and Groove (T&G) Ceiling Description: This uses individual planks of timber that have a "tongue" on one edge and a "groove" on the other. They are fitted together snugly, creating a seamless, high-quality wood finish. Common Local Timber for T&G: Odum, Mahogany, Emire. Characteristics: Provides a rich, natural, and luxurious look. Durable and long-lasting if well-maintained. Advantages: High Aesthetic Appeal: Gives a warm and classic appearance, popular in high-end homes, hotels, and offices. Durability: Solid wood is strong and can last for decades. Good Insulator: Wood has natural insulating properties. Disadvantages: High Cost: T&G ceilings are one of the most expensive options due to material and skilled labour costs. Maintenance: Requires periodic varnishing or polishing to maintain its look and protect it from insects. Susceptible to environmental changes: Can expand or contract with changes in humidity, potentially causing gaps. Plaster of Paris (P.O.P) / Gypsum Board Ceiling Description: This is arguably the most popular modern ceiling finish in Ghana today. The term "P.O.P Ceiling" usually refers to a system using Plasterboard (or Gypsum Board) which is screwed to a metal or timber frame. The joints are then filled with P.O.P compound and sanded smooth to create a monolithic, seamless surface. Decorative mouldings called cornices, made from P.O.P, are often added at the wall-ceiling junction. Materials & Process: Frame: Galvanised metal channels ("noggins") or light timber battens are fixed to the joists. Boarding: Plasterboard sheets are screwed to the frame. Finishing: Joints are taped with fibre tape and filled with P.O.P paste (P.O.P powder mixed with water). The entire surface is skimmed, sanded, and then painted. Advantages: Smooth & Modern Look: Provides a very clean, flat, and modern finish. Versatility: Can be shaped into various designs, curves, and levels (bulkheads) to hide lighting or for decorative effect. Fire Resistance: Gypsum is naturally fire-resistant. Good Sound Insulation: Offers better acoustic performance than plywood. Disadvantages: Skilled Labour: Requires skilled artisans for a good finish, which can increase labour costs. Messy Installation: The sanding process creates a lot of fine dust. Vulnerable to Water Damage: If there is a roof leak, the plasterboard will get damaged, stain, and eventually crumble. Not ideal for areas with frequent water exposure unless moisture-resistant boards are used. Soft Boards / Acoustic Boards Description: These are lightweight boards made from wood fibres, mineral wool, or fibreglass. They are designed specifically to absorb sound. They are often installed in a grid system, creating a "suspended ceiling". Characteristics: Usually come in standard square or rectangular tiles (e.g., 600x600mm). Have a porous or textured surface to trap sound waves. Typical Uses in Ghana: Offices, especially open-plan ones. Recording studios, auditoriums, school libraries, and conference rooms. Hospitals and clinics where noise reduction is important. Advantages: Excellent Sound Absorption: Its primary function. Easy Access to Services: Tiles can be easily removed to access wiring or plumbing in the ceiling void. Quick Installation: The grid system is fast to erect. Disadvantages: Fragile: The tiles can be easily damaged or stained. Aesthetics: The grid look is more functional than decorative and may not be suitable for homes. Can Absorb Moisture: Standard boards can sag in very humid environments. Paint Description: Paint is a final finish applied to other ceiling materials, not a standalone ceiling material itself. It is most commonly applied to P.O.P ceilings or directly onto the concrete soffit (the underside of a concrete slab). Types of Paint: Emulsion Paint: Water-based, most common for ceilings. Gives a matt finish which hides minor imperfections. Gloss/Satin Paint: Oil-based or acrylic, used in areas like kitchens and bathrooms because it is more durable and easier to clean. Process: Preparation: The surface must be clean, dry, and smooth. For P.O.P, this means ensuring all sanding is perfect. For concrete, it might mean filling cracks. Priming: A primer or first coat is applied to seal the surface. Top Coats: Two or more coats of the final paint are applied for an even finish. Factors Influencing the Choice of Ceiling Finish