6.7 Construction Trades and Specialties: Plumbing, Plastics, Doors and Windows, Finishes, and Electrical

6.7 Construction Trades and Specialties: Plumbing, Plastics, Doors and Windows, Finishes, and Electrical

The AMSTHC TOS area "Construction Trades and Specialties" has five one-item competencies:

1. Recall basic plumbing design, construction and installation.
2. Classify and determine plastics for construction.
3. Select details of doors and windows for proper application.
4. Identify and select finishing materials.
5. Understand basic electrical design, construction and installation.

Civil engineers coordinate these trades and are expected to know their vocabulary and basic rules. The governing codes are:

• the National Plumbing Code of the Philippines, under the Plumbing Law (RA 1378);
• the Philippine Electrical Code (PEC Part 1, under the Electrical Engineering Law, RA 7920);
• the Fire Code (RA 9514) for fire-rated doors.

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Plumbing Basics

Traps. A P-trap holds a water seal, typically about 50 to 100 mm deep, that blocks sewer gas. Seal loss is caused by siphonage (inadequate venting), evaporation (unused fixtures) and back-pressure.

Drainage fixture units express the relative discharge load of fixtures; pipe sizes are chosen from code tables based on total fixture units.

Common pipe materials:

• uPVC for cold water, drainage and vents;
• CPVC or PPR for hot water;
• galvanized iron (older systems);
• copper;
• HDPE for service lines and underground mains.

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Plastics in Construction

Thermoplastics (PVC, PE, PP) soften when heated and can be reshaped or welded. Thermosets (epoxy, polyester, phenolic) cure permanently. Plastics expand far more with temperature than steel, so long runs need expansion allowances. Many degrade in sunlight unless UV-stabilized.

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Doors and Windows

Door parts:

• the frame or jamb (head and side jambs, with a threshold at the floor);
• the leaf or shutter;
• the stop;
• the hardware: hinges, lockset, closer, panic bar.

Window parts:

• the frame (head, jambs, sill);
• the sash;
• mullions (vertical dividers) and transoms (horizontal dividers);
• glazing.

Glazing options:

• Annealed float glass is the basic type and breaks into sharp shards.
• Tempered glass is about four to five times stronger and breaks into small blunt pieces. It is required in hazardous locations such as doors and low panels.
• Laminated glass keeps its interlayer intact when broken; it is used in overhead and security glazing.
• Insulating glass units improve thermal performance.

Aluminum and uPVC frames resist rot. Wood needs treatment and finishing. All windows need proper sill slope and flashing to shed water.

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Finishing Materials

Paint systems follow a sequence: surface preparation (clean and repair; let new concrete or plaster cure and dry), primer or sealer, putty or skim coat where needed, then two or more finish coats. Alkali-resistant primers are used on new masonry. Epoxy or polyurethane systems are used for chemical or heavy-wear areas.

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Basic Electrical Design and Installation

The Philippine Electrical Code (PEC Part 1) governs building wiring. Houses are typically served at a nominal 220–230 V single-phase, and larger buildings by three-phase services.

Example. A $2.0\text{ kW}$ air conditioner on $230\text{ V}$ with power factor $0.85$ draws $I = 2{,}000/(230 \times 0.85) = 10.2\text{ A}$. Treated as a continuous load, the circuit needs $1.25(10.2) = 12.8\text{ A}$ of conductor capacity. The conductor size and breaker rating are then selected from the PEC ampacity tables for the insulation type and installation method.