Lesson Notes By Weeks and Term v3 - Senior Secondary 2
Job estimation and costing
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Job estimation and costing
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Subject: Painting And Decoration
Class: Senior Secondary 2
Term: 1st Term
Week: 10
Theme: Art Appreciation
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Students shouldbe able:Estimate and cost jobs in relation to:- the area and size of the job.- design in volved- quantity and quality Of materialsinvolve- time duration.
= NGN 5,
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0. Primer (for Door & Window Frames): Assume 0.5 litre is enough. Cost Primer (frames) = 0.5 litre × NGN 3,000/litre = NGN 1,
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0. Filler: NGN 1,500 Consumables: NGN 3,000 Total Material Cost: NGN 49,500 + NGN 15,000 + NGN 5,500 + NGN 1,500 + NGN 1,500 + NGN 3,000 = NGN 76,000 Step 3: Estimate Labour Time and Cost (for 1 painter)
Preparation (Walls & Ceiling): 47.51m2 × 0.5 hours/m2 = 23.76 hours Preparation (Door & Window): 1 door × 1 hr/door + 1 window × 1 hr/window = 2 hours Painting Emulsion (Walls & Ceiling, 2 coats): 47.51m2 × 0.15 hours/m2/coat × 2 coats = 14.25 hours Painting Gloss (Door & Window, 2 coats): (1 door × 0.5 hr/coat + 1 window × 0.5 hr/coat) × 2 coats = (0.5 + 0.5) × 2 = 2 hours Total Active Labour Hours: 23.76 + 2 + 14.25 + 2 = 42.01 hours.
Total Days (8-hour workday): 42.01 hours / 8 hours/day ≈ 5.25 days.
Total Labour Cost: 5.25 days × NGN 8,000/day = NGN 42,000 Step 4: Calculate Overheads and Profit Subtotal (Materials + Labour): NGN 76,000 + NGN 42,000 = NGN 118,000 Overhead (15%): 0.15 × NGN 118,000 = NGN 17,700 Cost of Project (Subtotal + Overhead): NGN 118,000 + NGN 17,700 = NGN 135,700 Profit (20% of Total Cost): (NGN 135,700 / (1 - 0.20)) - NGN 135,700 = (NGN 135,700 / 0.8) - NGN 135,700 = NGN 169,625 - NGN 135,700 = NGN 33,925 _Alternative simpler profit calculation:_ 20% of Cost of Project = 0.20 NGN 135,700 = NGN 27,140. (This will give a lower selling price but is common for simplicity in early stages). Let's use this simpler method for clarity. Total Selling Price (Cost + Profit): NGN 135,700 + NGN 27,140 = NGN 162,840 Summary of Estimation: Materials: NGN 76,000 Labour: NGN 42,000 Overhead: NGN 17,700 Profit: NGN 27,140 Total Estimated Cost to Client: NGN 162,840 Estimated Duration: Approximately 5-6 working days for one painter.
Brushes/Rollers/Trays: Tools, often factored as consumable or overhead.
Thinners/Turpentine: For oil-based paints and cleaning.
Calculating Paint Quantity: Paint coverage rate is usually indicated on the paint can (e.g., 8-10 m2/litre/coat).
Formula: Total litres = (Total Area m2 / Coverage Rate m2/litre) × Number of Coats. _
Example:_ A 50m2 wall, paint coverage 10m2/litre, 2 coats. Litres needed = (50m2 / 10m2/litre) × 2 coats = 5 litres/coat × 2 coats = 10 litres.
Waste Factor: Always add a percentage (e.g., 5-15%) for waste, spillages, and touch-ups. This is crucial in Nigerian work environments where conditions might lead to more waste.
Quality: High-quality paints offer better coverage, durability, finish, and longevity, reducing the need for frequent repainting, but come at a higher initial cost. Inferior quality might seem cheaper but could lead to dissatisfaction and premature failure.
D. Time Duration (Labour Cost) Time directly translates to labour cost.
Labour Rate: In Nigeria, painters are often paid daily or per square metre, or a lump sum for the entire project. Daily rates vary by location and skill level (e.g., NGN 5,000 - NGN 15,000 per day per painter).
Estimation of Time: Surface Preparation: Cleaning, sanding, filling, priming. This is often the most time-consuming stage (e.g., 0.5-1 hour per m2 depending on surface condition).
Painting Application: Plain walls: Typically 1-2 hours per 10-15 m2 per coat (for one painter).
Doors/Windows: 1-2 hours per standard door/window (for one painter, including frame).
Ceilings: Can be slightly slower than walls.
Drying Time: Between coats and for final cure. Although not active labour, it impacts project timeline.
Complexity of Design: As discussed, complex designs drastically increase labour time.
Number of Workers: More workers can shorten the project duration but requires more supervision.
Logistics: Travel time, site setup/pack-up, unforeseen delays (e.g., power outages, rain) should be considered.
Calculation: Total Labour Hours = (Estimated hours per m2 for preparation + Estimated hours per m2 for painting) × Total Area. Total Labour Cost = Total Labour Hours × Hourly Rate OR Number of Days × Daily Rate per Painter. _
Example:_ A 50m2 area: Preparation 0.5 hr/m2, Painting (2 coats) 0.2 hr/m
2. Total active labour hours = (0.5 + 0.2) hr/m2 × 50m2 = 0.7 hr/m2 × 50m2 = 35 hours.
If a painter works 8 hours/day: 35 hours / 8 hours/day ≈ 4.4 days. If daily rate is NGN 8,000: 4.4 days × NGN 8,000/day = NGN 35,200. 2.
3. General Procedure for Job Estimation and Costing (Step-by-Step)
1. Site Inspection: Visit the site to assess: Nature of the surface (new plaster, old paint, rough concrete, wood, metal). Condition of the surface (cracks, peeling paint, dirt, moisture). Accessibility (high ceilings, cramped spaces). Existing colours/finishes. Logistics (power, water availability, security).
2. Take Measurements: Accurately measure all surfaces to be painted or decorated (walls, ceilings, doors, windows, frames, cornices, skirtings). Sketch a diagram if necessary.
3. Identify Design Requirements: Discuss with the client the desired colours, patterns, textures, or specific artistic designs.
4. Determine Material Specifications: Based on surface type, desired finish, and budget, select appropriate paints (emulsion, gloss, textured, etc.), primers, fillers, and other consumables.
5. Calculate Material Quantities: Use the measured areas and paint coverage rates, adding a waste factor (e.g., 10-15%).
6. Obtain Material Prices: Source current market prices for all specified materials from local suppliers in Nigeria (e.g., paint shops, hardware stores).
7. Estimate Labour Time: Break down the job into stages (preparation, first coat, second coat, finishing) and estimate the time required for each, considering design complexity and surface condition.
8. Calculate Labour Cost: Determine the number of painters and their daily/hourly rates or agree on a fixed labour cost for the project.
9. Factor in Overheads and Profit: Overheads: Indirect costs like transport, fuel, tools/equipment depreciation, phone bills, site supervision, administrative costs. Often calculated as a percentage of material + labour cost (e.g., 10-20%). * Profit Margin: The desired profit for the business (e.g., 15-30% of total cost).
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0. Prepare Quotation: Present a detailed breakdown of costs to the client, clearly stating This section delves into the core concepts required for accurate job estimation and costing in painting and decoration. 2.
1. Definition of Job Estimation and Costing Job Estimation: The process of predicting the approximate total cost, materials, and time required to complete a specific painting and decoration project. It involves careful calculation, experience, and knowledge of market rates.
Job Costing: The process of systematically tracking and accumulating the actual expenses (materials, labour, overheads) incurred for a specific job, to determine its actual profitability and inform future estimations. For this lesson, the focus is on pre-project estimation. 2.
2. Components of Job Estimation and Costing
A. Area and Size of the Job Accurate measurement is the foundation of estimation.
Measuring Tools: Tape measure (steel or fabric), laser distance measurer (if available), pencil, and paper.
Units of Measurement: Square Metre (m2): Used for flat surfaces like walls, ceilings, and floors (for floor painting/epoxy).
Linear Metre (m): Used for linear elements like skirtings, cornices, architraves, door/window frames.
Calculation of Area: Rectangular Surfaces (Walls, Ceilings): Area = Length (m) × Height/Width (m) _
Example:_ A wall 4m long and 3m high has an area of 4m × 3m = 12m
2. Irregular Surfaces: May require breaking down into simpler geometric shapes (rectangles, triangles) and summing their areas.
Deductions for Openings: Large openings (doors, windows) that will not be painted or decorated should be deducted from the wall area. A common rule of thumb in Nigeria is to deduct openings larger than 1.5m2 if they will not be painted. Smaller openings or those requiring painting (e.g., door frames) are often ignored or accounted for in a lump sum for complexity. _
Example:_ A 12m2 wall has a door of 0.9m × 2.1m = 1.89m
2. Net area = 12m2 - 1.89m2 = 10.11m
2. Total Surface Area: Sum of all measured wall, ceiling, and other surfaces requiring work. B. Design Involved The complexity of the design significantly impacts material consumption, labour time, and overall cost.
Plain Colours (Monochromatic): Simplest and cheapest. Requires less precision and time.
Stripes/Patterns: Requires careful masking, multiple paint colours, more time for application and drying between colours, and increased labour. Textured Finishes (e.g., Sandtex, Marmorino): Requires specialized materials, specific application tools, and skilled labour. Often involves multiple layers and longer drying times.
Stenciling/Decals: Requires precision, additional materials (stencils, adhesive), and more labour time.
Murals/Hand-Painted Designs: Highly skilled labour, specialized paints, significant time investment, and artist fees. These are typically priced per project or per square metre with a premium.
Impact on Cost: Labour: Complex designs demand more skilled painters and longer hours.
Materials: Multiple colours, specialized finishes, and masking tapes increase material cost.
Waste: More complex designs can lead to higher material waste during application.
C. Quantity and Quality of Materials Involved Materials are a major cost component.
Types of Paint: Emulsion Paint (Matt/Silk): Common for interior walls and ceilings. Relatively affordable.
Gloss Paint (Oil-based/Water-based): For doors, windows, metalwork, wood. More durable, but often more expensive and requires specialized thinners for oil-based.
Textured Paint: For creating decorative effects on walls, usually more expensive per litre and has lower coverage.
Specialty Paints: Anti-fungal, weather-shield (for exteriors), epoxy (for floors), masonry paint. Higher cost, specific applications.
Ancillary Materials: Primers/Undercoats: Essential for preparing surfaces, improving adhesion, and ensuring uniform finish. Cost depends on type (PVA, alkali-resistant, universal).
Fillers/Putties: For patching holes and cracks (e.g., P.O.P. filler, mastic).
Sandpaper: For surface preparation.
Masking Tape/Drop Cloths/Nylon Sheets: For protection.
Brushes/Rollers/Trays: Tools, often factored as consumable or overhead.
Thinners/Turpentine: For oil-based paints and cleaning.
Calculating Paint Quantity: Paint coverage rate is usually indicated on the paint can (e.g., 8-10 m2/litre/coat).
Formula: Total litres = (Total Area m2 / Coverage Rate m2/litre) × Number of Coats. _
Example:_ A 50m2 wall, paint coverage 10m2/litre, 2 coats. Litres needed = (50m2 / 10m2/litre) × 2 coats = 5 litres/coat × 2 coats = 10 litres.
Waste Factor: Always add a percentage (e.g., 5-15%) for waste, spillages, and touch-ups. This for each, considering design complexity and surface condition.
8. Calculate Labour Cost: Determine the number of painters and their daily/hourly rates or agree on a fixed labour cost for the project.
9. Factor in Overheads and Profit: Overheads: Indirect costs like transport, fuel, tools/equipment depreciation, phone bills, site supervision, administrative costs. Often calculated as a percentage of material + labour cost (e.g., 10-20%).
Profit Margin: The desired profit for the business (e.g., 15-30% of total cost).
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0. Prepare Quotation: Present a detailed breakdown of costs to the client, clearly stating what is included and excluded. Worked
Example: Painting a Small Room in a Nigerian Home Room Dimensions: Length = 4m, Width = 3m, Height = 2.8m.
Door: 0.9m x 2.1m (one).
Window: 1.2m x 1.5m (one).
Work: Paint walls and ceiling with quality emulsion (2 coats), paint door and window frames with gloss paint (2 coats).
Assumptions: Emulsion coverage: 10 m2/litre/coat.
Gloss coverage: 12 m2/litre/coat.
Material waste: 10%.
Emulsion price: NGN 4,500/litre.
Gloss paint price: NGN 5,500/litre.
Primer price: NGN 3,000/litre (needed for walls and wood).
Primer coverage: 12m2/litre/coat.
Filler: NGN 1,500/kg (1kg sufficient for small room). Masking tape, sandpaper, brushes (consumables): NGN 3,
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0. Labour rate: NGN 8,000/painter/day.
Preparation time: 0.5 hours/m2 for walls/ceiling, 1 hour/door, 1 hour/window.
Painting time: 0.15 hours/m2/coat for walls/ceiling, 0.5 hours/door/coat, 0.5 hours/window/coat.
Overhead: 15% of material + labour.
Profit: 20% of total cost.
Step 1: Calculate Area and Size Wall Area: (2 × Length × Height) + (2 × Width × Height) = (2 × 4m × 2.8m) + (2 × 3m × 2.8m) = 22.4m2 + 16.8m2 = 39.2m2 Ceiling Area: Length × Width = 4m × 3m = 12m2 Door Opening Area: 0.9m × 2.1m = 1.89m2 (deductible)
Window Opening Area: 1.2m × 1.5m = 1.8m2 (deductible)
Net Wall Area for Emulsion: 39.2m2 - 1.89m2 - 1.8m2 = 35.51m2 Door Frame Perimeter: (2.1m + 0.9m) × 2 = 6m (Assume 2 faces, so 6m × 2 = 12 linear meters)
Window Frame Perimeter: (1.5m + 1.2m) × 2 = 5.4m (Assume 2 faces, so 5.4m × 2 = 10.8 linear meters) _Note on frames:_ For simplicity, linear meters of frames are often converted to an equivalent small area or priced per item. Here we will use per item labour and per litre gloss paint.
Step 2: Calculate Material Quantities and Cost Emulsion Paint (Walls & Ceiling): Total Area = 35.51m2 (walls) + 12m2 (ceiling) = 47.51m2 Litres needed (2 coats) = (47.51m2 / 10m2/litre) × 2 coats = 4.751 × 2 = 9.502 litres. With 10% waste = 9.502 × 1.10 = 10.45 litres. (Round up to 11 litres, or 2 x 5-litre cans + 1 x 1-litre can, or 1 x 20-litre can if available and cost-effective). Let's say 1 x 10-litre can + 1 x 1-litre can, total 11 litres. Cost Emulsion = 11 litres × NGN 4,500/litre = NGN 49,
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0. Primer (Walls & Ceiling): Total Area = 47.51m
2. Litres needed (1 coat) = (47.51m2 / 12m2/litre) = 3.96 litres. With 10% waste = 3.96 × 1.10 = 4.35 litres. (Round up to 5 litres). Cost Primer (walls/ceiling) = 5 litres × NGN 3,000/litre = NGN 15,
0
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0. Gloss Paint (Door & Window Frames): Assume 1 litre of gloss paint is enough for 1-2 doors and 1-2 windows (2 coats). Cost Gloss = 1 litre × NGN 5,500/litre = NGN 5,
5
0
0. Primer (for Door & Window Frames): Assume 0.5 litre is enough. Cost Primer (frames) = 0.5 litre × NGN 3,000/litre = NGN 1,
5
0
0. Filler: NGN 1,500 Consumables: NGN 3,000 Total Material Cost: NGN 49,500 + NGN 15,000 + NGN 5,500 + NGN 1,500 + NGN 1,500 + NGN 3,000 = NGN 76,000 Step 3: Estimate Labour Time and Cost (for 1 painter)
Preparation (Walls & Ceiling): 47.51m2 × 0.5 hours/m2 = 23.76 hours * Preparation (Door & Window): 1 door × 1
This topic is profoundly practical and connects directly to various aspects of Nigerian life and economy.
Entrepreneurship and Self-Employment: This is perhaps the most direct application. Many Nigerian youths seek vocational skills for self-reliance. Mastering job estimation allows individuals to start their own painting and decoration businesses. They can confidently bid for contracts, provide professional quotations, manage costs, and ultimately build a profitable enterprise, contributing to job creation for others. For instance, a student can apply this knowledge to estimate the cost of painting a neighbour's house, a small office, or even getting involved in community projects. Budgeting and Financial Literacy for Households/Small Businesses: Beyond becoming a painter, this knowledge equips individuals to be informed clients. When commissioning painting work for their homes, shops, or offices, they can understand quotations, challenge unreasonable prices, and make informed decisions about material quality and design choices based on their budget. This promotes financial prudence and protects consumers from exploitation in the Nigerian market. For example, a student can help their family budget for renovating their living room by understanding the true costs involved. Project Management and Construction Industry Integration: The painting and decoration sector is an integral part of Nigeria's booming construction industry. Accurate estimation and costing are vital for larger construction projects (residential estates, commercial buildings, infrastructure). Professionals with these skills can work as estimators, project managers, or consultants, ensuring that painting sub-contracts are well-planned, cost-effective, and delivered on time. They integrate with architects, builders, and other artisans to ensure seamless project execution and prevent cost overruns, which are common challenges in Nigerian construction.