--- title: "Two-room building: excavation, PCC, brick, plaster" subject: "Estimating and Costing" chapter: 6 key: "semester_7/estimating_and_costing:building-h-two-room-fig1" source: https://www.bctengineer.com/q/semester_7/estimating_and_costing/building-h-two-room-fig1 site: BCT Engineering --- # Two-room building: excavation, PCC, brick, plaster Estimating and Costing · Chapter 6: Detailed Estimate - Asked in: 2078 Bhadra, 5 marks - Video: [Learn Quantity Surveying|Calculation Earth work, Concrete, Brick work In foundation, Plinth and DPC.](https://www.youtube.com/watch?v=1s_b4cNeS1U) — Civil Engineering Survey - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/estimating_and_costing/building-h-two-room-fig1 - Whole chapter: https://www.bctengineer.com/md/semester_7/estimating_and_costing/chapter-6 ## Question Prepare detailed estimate of the item of work from the building drawing (figure 1) attached herewith: a) Earthwork in excavation in foundation b) PCC (1:3:6) in foundation c) Brick work in 1:6 cement sand mortar up to Plinth d) Plastering work 1:4 for the ceiling. [Figure 1: Plan 7900 mm overall length × 5400 mm; two rooms 3450 × 3300 mm and 3400 × 4600 mm; front verandah/open portion 1300 mm; external bays 900, 2400, 1300, 2400, 900 mm; internal partition wall 250 mm; external wall 400 mm (as marked 400); door D 900 × 2100, window W 2400 × 1500. Sections of 0.25 m wall and 0.40 m wall: foundation PCC (1:3:6) with flat brick soling, brickwork in (1:6) CM, 1:1 cement pointing, 100 thick PCC (1:3:6), 150 stone soling, rammed earth, P.C.C. (1:2:4) for RCC roof; wall height 3000 mm, sill 1500/2100 mm. Details approximate.] ## Short answer Using centre-line method: earthwork excavation 24.39 m³, PCC (1:3:6) 8.13 m³, brickwork in 1:6 mortar up to plinth 12.00 m³, and 1:4 ceiling plaster 32.03 m². ## Answer #### Reading of the figure Overall 7.9 m × 5.4 m: 0.40 + 3.45 + 0.25 + 3.40 + 0.40 = 7.90 m and 0.40 + 4.60 + 0.40 = 5.40 m. Room 1 (3.45 × 3.30 m) has the 1.30 m open verandah in front; Room 2 (3.40 × 4.60 m) is full depth. Walls: external 400 mm, partition 250 mm. The partition runs the full depth of Room 2 (4.60 m clear); Room 1's front wall stops against the partition, and Room 2's front wall is carried across the end of the partition (to x = 3.85 m) to close the corner. Centre-line lengths of the 400 mm walls: back 7.50 + right 5.00 + left 3.70 + Room 1 front 3.65 (to the partition face) + Room 2 front 3.85 (to the far face of the partition) = 23.70 m; 250 mm partition = 4.60 m clear. Foundation assumed: PCC 1:3:6 0.30 m thick, projecting 0.30 m each side of the wall (so 1.00 m and 0.85 m wide), trench depth 0.90 m, one brick step 0.15 m high and 0.10 m wider each side than the wall, then the wall to plinth (0.45 m above GL). Junction adjustments (centre-line method): the partition trench and PCC stop at the edges of the outer-wall trenches, so their length is 4.60 − 2 × 0.30 = 4.00 m; the partition step is 4.60 − 2 × 0.10 = 4.40 m. Room 1's front-wall trench and step stop at the edge of the partition's trench and step (3.65 − 0.30 = 3.35 m and 3.65 − 0.10 = 3.55 m). At the free end of Room 2's front wall, the trench and step run 0.30 m and 0.10 m past the wall (3.85 + 0.30 = 4.15 m and 3.95 m). The net 400 mm wall length is therefore 23.70 m for the trench, PCC, step and wall alike. #### a) Earthwork in excavation | Item | No. | L (m) | B (m) | H/D (m) | Qty (m³) | |---|---|---|---|---|---| | Trench, 400 mm walls (w = 1.0) | 1 | 23.700 | 1.000 | 0.900 | 21.330 | | Trench, 250 mm wall (w = 0.85) | 1 | 4.000 | 0.850 | 0.900 | 3.060 | | **Total** | | | | | **24.390** | #### b) PCC (1:3:6) in foundation | Item | No. | L (m) | B (m) | H/D (m) | Qty (m³) | |---|---|---|---|---|---| | PCC 1:3:6, 400 mm walls | 1 | 23.700 | 1.000 | 0.300 | 7.110 | | PCC 1:3:6, 250 mm wall | 1 | 4.000 | 0.850 | 0.300 | 1.020 | | **Total** | | | | | **8.130** | #### c) Brickwork in 1:6 CM up to plinth Wall height from the step = 0.90 − 0.30 − 0.15 + 0.45 = 0.90 m. | Item | No. | L (m) | B (m) | H/D (m) | Qty (m³) | |---|---|---|---|---|---| | 400 wall: brick step (0.6 × 0.15) | 1 | 23.700 | 0.600 | 0.150 | 2.133 | | 400 wall: wall to plinth | 1 | 23.700 | 0.400 | 0.900 | 8.532 | | 250 wall: brick step (0.45 × 0.15) | 1 | 4.400 | 0.450 | 0.150 | 0.297 | | 250 wall: wall to plinth | 1 | 4.600 | 0.250 | 0.900 | 1.035 | | **Total** | | | | | **11.997** | #### d) 1:4 plastering of ceiling | Item | No. | L (m) | B (m) | H/D (m) | Qty (m²) | |---|---|---|---|---|---| | Room 1: 3.45 × 3.30 | 1 | 3.450 | 3.300 | – | 11.385 | | Room 2: 3.40 × 4.60 | 1 | 3.400 | 4.600 | – | 15.640 | | Verandah soffit 3.85 × 1.30 (outer face to partition) | 1 | 3.850 | 1.300 | – | 5.005 | | **Total** | | | | | **32.030** | **Answer:** Excavation 24.39 m³; PCC 8.13 m³; brickwork to plinth 12.00 m³; ceiling plaster 32.03 m² (assumed details). ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Why are the 400 mm walls and the 250 mm partition calculated on separate lines in excavation and PCC? A. They have different foundation widths (1.00 m and 0.85 m), so one length x width cannot be used B. The partition is built in a different mortar C. Only 400 mm walls need excavation D. Their trench depths differ because of different soil Answer: A. Foundation width depends on wall thickness plus the PCC projection, so each wall type is multiplied by its own width. (Key point: Separate wall groups) 2. PCC projects 0.30 m each side of the wall. What is the trench width for the 250 mm partition? A. 0.55 m B. 1.00 m C. 0.85 m D. 0.60 m Answer: C. Width = wall thickness + 2 x projection = 0.25 + 0.60 = 0.85 m (and 0.40 + 0.60 = 1.00 m for the 400 mm wall). (Key point: Foundation width) 3. With trench depth 0.90 m, PCC 0.30 m, brick step 0.15 m and plinth 0.45 m above GL, what is the wall height to plinth? A. 0.45 m B. 0.90 m C. 1.05 m D. 1.35 m Answer: B. Height = 0.90 - 0.30 - 0.15 + 0.45 = 0.90 m: the depth left above the step plus the plinth above ground level. (Key point: Wall height above step) 4. Why does the ceiling plaster include a separate 5.33 m2 line for the verandah? A. The verandah floor is plastered B. It is the wall plaster of the verandah C. It is the extra plaster for ceiling cornices D. The roof over the open verandah has an underside (soffit) that also receives plaster Answer: D. Ceiling plaster covers every exposed underside of the roof slab, including the part over the open verandah (4.10 x 1.30). 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