--- title: "One-roomed building: earthwork, plaster, openings" subject: "Estimating and Costing" chapter: 6 key: "semester_7/estimating_and_costing:one-room-a-fig-c" source: https://www.bctengineer.com/q/semester_7/estimating_and_costing/one-room-a-fig-c site: BCT Engineering --- # One-roomed building: earthwork, plaster, openings Estimating and Costing · Chapter 6: Detailed Estimate - Asked in: 2082 Bhadra - Video: [Estimation of One Room - 2023 || Long wall and Short wall method || @CivilConceptandPlans](https://www.youtube.com/watch?v=bqrq47VnFaE) — Civil Concept and Plans - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/estimating_and_costing/one-room-a-fig-c - Whole chapter: https://www.bctengineer.com/md/semester_7/estimating_and_costing/chapter-6 ## Question Prepare detailed estimate for the following items of works for one-roomed building: (Use fig.c) a) Earthwork in excavation. b) 12 mm thick plaster work inside and outside the building. c) Door and windows frame and shutters. [Figure c: One-roomed building. Ground floor plan: external length 4200 mm and width 3000 mm (plus 1200 projection), wall 230 mm thick, offsets 2000, 2000, 470, 600, 470, 230 mm, door D1 1000 × 2100 mm, windows W1 600 × 1000 mm, 4000 mm and 1400 mm room dimensions. Section X-X: height 2650 mm, plinth 450 mm, 300 × 300 mm plinth tie-beam, M20 RCC slab 125 mm with 600 mm projection, brickwork (1:6) above plinth, stone masonry in foundation, PCC (1:2:4) 75 mm with brick soling and compacted earth, foundation width 600/400/300 mm. All dimensions in mm; details approximate.] ## Short answer Centre-line length 13.48 m. Earthwork: 0.6 m wide ×0.9 m deep trench, volume 7.28 m³. 12 mm plaster: inside 32.65 m², outside 43.14 m², total 75.79 m². Door/window: frames 0.087 m³ timber; shutters 2.10 m² (door) and 1.20 m² (windows), total 3.30 m² (assumed details). ## Answer The figure is approximate, so the following reading is used: building 4.2 m × 3.0 m outside, walls 0.23 m; one door D1 1.0 × 2.1 m; two windows W1 0.6 × 1.0 m (number assumed); inside height 2.65 m; plinth 0.45 m; RCC slab 125 mm. The 1200 mm projection is taken as a slab canopy and is not walled. Centre-line length = 2[(4.2 − 0.23) + (3.0 − 0.23)] = 13.48 m. #### a) Earthwork in excavation Foundation (stone masonry, widths 600/400/300 mm) needs a trench 0.60 m wide; assumed depth 0.90 m (75 mm soling, 75 mm PCC 1:2:4, masonry above). | Item | No. | L (m) | B (m) | H/D (m) | Qty (m³) | |---|---|---|---|---|---| | Trench, centre-line | 1 | 13.480 | 0.600 | 0.900 | 7.279 | | **Total** | | | | | **7.279** | #### b) 12 mm plaster, inside and outside Inside perimeter = 2(3.74 + 2.54) = 12.56 m; outside perimeter = 2(4.2 + 3.0) = 14.40 m. Outside height taken from GL to top of slab edge = 0.45 + 2.65 + 0.125 = 3.225 m. Inside: | Item | No. | L (m) | B (m) | H/D (m) | Qty (m²) | |---|---|---|---|---|---| | Inside wall | 1 | 12.560 | 2.650 | – | 33.284 | | Deduct door | -1 | 1.000 | 2.100 | – | -2.100 | | Deduct windows | -2 | 0.600 | 1.000 | – | -1.200 | | Add reveals, door (3 sides × 0.23) | 1 | 1.196 | – | – | 1.196 | | Add reveals, windows | 2 | 0.736 | – | – | 1.472 | | **Total** | | | | | **32.652** | Outside: | Item | No. | L (m) | B (m) | H/D (m) | Qty (m²) | |---|---|---|---|---|---| | Outside wall (plinth + wall + slab edge) | 1 | 14.400 | 3.225 | – | 46.440 | | Deduct door | -1 | 1.000 | 2.100 | – | -2.100 | | Deduct windows | -2 | 0.600 | 1.000 | – | -1.200 | | **Total** | | | | | **43.140** | Total plaster = 32.65 + 43.14 = **75.79 m²**. #### c) Doors and windows Frame section assumed 100 × 75 mm. | Item | Working | Quantity | |---|---|---| | Door frame (2 × 2.1 + 1.0) | 5.2 × 0.10 × 0.075 | 0.0390 m³ | | Window frames, 2 nos. (2 × 1.0 + 2 × 0.6) | 2 × 3.2 × 0.10 × 0.075 | 0.0480 m³ | | Door shutter | 1.0 × 2.1 | 2.10 m² | | Window shutters | 2 × 0.6 × 1.0 | 1.20 m² | **Answer:** Excavation = 7.28 m³; plaster = 75.79 m²; frames = 0.087 m³ of timber; shutters = 3.30 m². ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. For outside 4.2 x 3.0 m with 0.23 m walls, what is the centre-line length? A. 2[(4.2 - 0.23) + (3.0 - 0.23)] = 13.48 m B. 2(4.2 + 3.0) = 14.40 m C. 2[(4.2 + 0.23) + (3.0 + 0.23)] D. 2(3.74 + 2.54) = 12.56 m Answer: A. Centre-line sides equal the outside dimension minus one wall thickness. (Key point: Centre-line length) 2. What height is used for the outside plaster? A. 2.65 m B. 0.45 + 2.65 + 0.125 = 3.225 m C. 2.65 + 0.125 D. 3.0 m Answer: B. It runs from GL over plinth, wall height and slab edge. (Key point: Outside plaster height) 3. Why are reveals added inside after deducting openings? A. Plaster also covers the jambs and head of the openings B. Openings are not deducted C. Reveals are skirting D. Reveals replace deductions Answer: A. Plaster returns into the 0.23 m wall thickness around the openings. (Key point: Plaster reveals) 4. What length of door frame is used for D1 1.0 x 2.1 m? A. 2 x 2.1 + 1.0 = 5.2 m B. 2(1.0 + 2.1) C. 2.1 + 1.0 D. 4 x 2.1 Answer: A. Two vertical posts and a head, no sill. 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