Grade 10 building construction Building Services – Plumbing Materials Notes
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Building Construction — Building Services
Subtopic: Plumbing Materials (Learner age: 15 • Kenya)
Specific learning outcomes
- Identify materials used in plumbing.
- Describe properties of materials used in plumbing.
- Select materials for specified plumbing uses.
- Recognise the importance of materials used in plumbing.
Key plumbing materials — quick reference
PVC / uPVC (Polyvinyl Chloride) 🟦
Common uses: cold water supply, waste/drain pipes, soil stacks, stormwater. In Kenya, widely available and affordable from hardware "duka la vifaa".
Properties:
- Lightweight, smooth internal surface → low friction, good flow.
- Corrosion resistant and chemically stable.
- Not suitable for direct hot-water at high temperature unless CPVC.
- Easy to cut and join with solvent cement or fittings.
Galvanized Iron (GI) / Mild Steel ⚙️
Common uses: older water supply lines, structural piping; increasingly replaced by plastic and copper in Kenya.
Properties:
- Strong and rigid; can handle pressure.
- Galvanized coating resists corrosion for a time, but may rust in the long term.
- Heavy and harder to join (threaded joints, welding).
- Internal corrosion can reduce flow and contaminate water.
Copper 🟫
Common uses: potable hot & cold water, where durability and hygiene are needed.
Properties:
- Excellent corrosion resistance and long life.
- Good for hot water — withstands high temperature.
- Relatively expensive compared to PVC or GI.
- Joined by soldering or compression fittings.
CPVC, PPR, HDPE, PEX (modern plastics) 🔵
Common uses: hot and cold water lines, underground mains, flexible connections.
Properties:
- CPVC — suitable for hot water (higher temp tolerance than PVC).
- PPR and PEX — flexible, fewer joints, fast to install.
- HDPE — used for underground mains, very durable and resistant to chemicals.
- Generally light, corrosion-free, and long lifespan.
Cast Iron 🧱
Common uses: soil/waste pipes in multi-storey buildings, heavy-duty drainage.
Properties:
- Strong, good sound insulation (less noise from waste flow).
- Heavy and requires special fittings and handling.
- Prone to corrosion unless protected/coated.
Fittings & Other materials (Brass, Stainless Steel, Rubber) 🔩
Uses: taps, valves, connectors, flexible hoses, washers and seals.
Properties:
- Brass — good corrosion resistance, commonly used for taps and valves.
- Stainless steel — strong, hygienic, used for appliances and fittings.
- Rubber (EPDM) — used for washers and seals; choices affect leak resistance.
How to select the right material (simple guide)
- Purpose: For drinking water choose safe, non-toxic materials (copper, CPVC, PPR, certified PVC). For drainage choose larger-diameter PVC or cast iron.
- Temperature: Use CPVC, copper, or PEX for hot water; ordinary PVC only for cold water.
- Pressure: Metal pipes (copper, GI) and some plastics (PEX, PPR) handle higher pressure better than thin-walled PVC.
- Location: Underground — use HDPE or buried-rated pipes; exposed outdoor piping must resist sunlight (UV) or be painted/shielded.
- Durability vs cost: Balance initial cost and expected life; cheap pipe may cost more through leaks and repairs.
- Availability & skills: Choose materials available locally and that installers (mason/plumber) can join correctly.
- Hygiene & maintenance: Smooth internal surfaces reduce deposit build-up; easily replaceable fittings reduce maintenance time.
Importance of choosing correct plumbing materials
- Protects health — prevents contamination of drinking water.
- Reduces leaks and water loss — saves money and avoids property damage.
- Longer life and lower maintenance — fewer replacements and disruptions.
- Energy efficiency — correct materials for hot water reduce heat loss.
- Safety — correct material for gas lines (where used) and high-pressure systems.
Suggested learning experiences and activities (Kenyan context)
1. Field visit to a hardware store (duka la vifaa)
Task: In groups, list 6 types of pipes and 6 fittings found. Note prices and common brands. Identify labels (uPVC, CPVC, PPR, HDPE, GI).
Learning outcome: identify materials and learn local availability and cost.
2. Site visit or demo — examine a simple house plumbing system
Task: Observe water inlet, distribution and drainage. Sketch where different materials are used (e.g., PVC for drains, PPR for hot water).
Learning outcome: relate materials to real use and selection.
3. Classroom tests — small experiments (safe, supervised)
- Leak test: Join two short pipe pieces (PVC vs PPR) and pressurize gently with water to compare ease of sealing.
- Corrosion demo: Place small metal samples (steel, copper) in vinegar/water for a few days to observe rust vs no rust.
- Flex test: Bend short pieces of PEX/HDPE vs PVC to observe flexibility and break point.
4. Practical skill — replace a tap washer or change a leaking flexible hose
Task: Under teacher supervision, practice simple maintenance: turn off valve, remove hose, replace washer/seal, test for leaks.
Learning outcome: appreciate importance of quality fittings and seals.
5. Design challenge — choose materials for a small school rainwater harvesting system
Task: In groups, sketch a system for collecting, storing and distributing rainwater. Select pipe types for gutters, downpipes, filters and storage taps, and justify choices (cost, durability, hygiene).
Learning outcome: select materials for specified use and explain reasons.
Simple checks students can do at home (safety first)
- Look under the sink: identify pipe types and fittings and make a list.
- Observe water meter/connection: is the incoming pipe metal or plastic?
- Ask a parent/guardian when the last plumbing repair was done — what material was used and why?
Quick assessment questions (for class/homework)
- Name four materials used in plumbing and give one use for each.
- Why is PVC commonly used for drainage in Kenya?
- Which materials are suitable for hot water pipes and why?
- List three reasons why choosing the right material matters for household plumbing.
Note to teacher: adapt demonstrations to available materials. Emphasise safety (turn off main water before working on real pipes) and proper disposal of waste materials. Where possible invite a local plumber to speak about common local practices and challenges.