- 2082 Baisakh · 5 marks
Deduction rules: brickwork, plastering, painting
Short answer
Brickwork deducts openings over 0.1 m2 in full; plaster deducts none up to 0.5 m2, one face only from 0.5 to 3 m2, both faces above 3 m2. Painting follows plaster rules. For a 6x3x0.23 m wall with 1.44 m2 window and 2.10 m2 door, net brickwork is 3.33 m3 and plaster/painting is 32.46 m2.
Explain the rules for deduction in quantities for brickwork, plastering and painting works with an example.
Quantities are measured net, so openings and voids are deducted as per IS 1200 and the Nepal practice. The rules depend on the size of the opening.
Brickwork (IS 1200 Part 3)
- Openings (doors, windows, ventilators) larger than 0.1 m² are deducted in full: opening area x wall thickness.
- No deduction is made for openings up to 0.1 m², or for the ends of joists, rafters, purlins and similar members up to 0.1 m² in section.
- Reinforced concrete lintels, beams and columns inside the wall (with the bearings of lintels and beams) are deducted from the brickwork.
Plastering (IS 1200 Part 12)
| Opening | Deduction |
|---|---|
| up to 0.5 m² | none |
| 0.5 to 3 m² | one face only, no addition for reveals |
| above 3 m² | both faces, and reveals measured and added |
Painting (IS 1200 Part 15)
- Painting on plastered walls follows the plaster rule; openings up to 0.5 m² are not deducted.
- For doors and windows, painting is measured on the opening area with the multiplying factors of IS 1200 (for example 1.30 for panelled, 1.80 for louvered).
Example
Brick wall 6 m x 3 m x 0.23 m thick, with a window 1.2 x 1.2 m (1.44 m²) and a door 1.0 x 2.1 m (2.10 m²), plastered on both faces.
- Brickwork: 6 x 3 x 0.23 = 4.14 m³; deduct (1.44 + 2.10) x 0.23 = 0.814 m³; net = 3.33 m³.
- Plaster (both faces): gross = 2 x 18 = 36 m². Both openings are between 0.5 and 3 m², so deduct one face only: 36 - 3.54 = 32.46 m².
- Painting of the plastered surface: same as the plaster quantity, 32.46 m².
✓ Answer checked by Claude Opus 5.5 (high effort)
Related questions
- Deduction rules for plastering openings · Estimating and Costing, chapter 2 · asked 3×
- Single room: excavation, brickwork, plaster, shutter · Estimating and Costing, chapter 6
- Underground RCC tank: brickwork, steel (fig a) · Estimating and Costing, chapter 6
- Septic tank: excavation, brickwork, PCC · Estimating and Costing, chapter 6
- Bill of quantities for RCC T-beam bridge · Estimating and Costing, chapter 2
- Underground RCC tank: brickwork 1:4, M20 PCC, steel · Estimating and Costing, chapter 6
- Cement and sand for 100 m² plastering numerical · Building Technology, chapter 3 · asked 2×
- Cement and sand for 200 m² plastering numerical · Building Technology, chapter 3 · asked 2×
- Pointing, plastering defects, oil paint constituents · Building Technology, chapter 9 · asked 2×
- Short note: Mortars used in plastering · Building Technology, chapter 3