How is the total centre-line length of walls obtained for the foundation items?

Outer-wall centre-line 21.00 m plus the central partition 3.27 m = 24.27 m

Outer-wall centre-line only, 21.00 m

Overall perimeter 2(7.23 + 3.73) = 21.92 m

Outer-wall centre-line 21.00 m plus twice the partition length

Which dimensions are multiplied with the centre-line length to get the excavation quantity of 14.95 m3?

Width 0.77 m (PCC width) and depth 0.80 m

Width 0.23 m (wall thickness) and depth 0.80 m

Width 0.69 m (first brick step) and depth 0.45 m

Width 0.77 m and depth 0.15 m (PCC thickness)

Why is the superstructure brickwork 11.175 m3 and not the full wall volume of 13.397 m3?

The volumes of doors and windows (length x 0.23 x height) are deducted from the full wall volume

The plinth portion is deducted from the wall

Only the outer walls are counted and the partition is omitted

The mortar volume is deducted from the brickwork

Why is the door frame length taken as 2 x 2.1 + 1.2 and not 2 x 2.1 + 2 x 1.2?

Door frames have no bottom sill member, only two posts and a head

The head is hidden inside the lintel

The door frame sill is measured under floor finishes

Door frames are measured only up to the plinth

2080 Baisakh · 3+2+4+3 marks

Building: excavation, PCC, brick, wood work

Short answer

Centre-line method gives excavation 14.62 m³, PCC (1:3:6) 2.741 m³, superstructure brickwork 11.18 m³, and door/window frame timber 0.197 m³.

Prepare detailed estimate of the following items of works from the given building drawing attached fig 3. a) Earth work in excavation in foundation b) Plain cement concrete (1:3:6) in foundation. c) Brickwork in 1:6 C.S. in super structure wall. d) Wood work for door and window frame. [Fig 3: plan, overall length 7250 mm (1265 + 1200 + 2300 + 1200 + 1265), width 3730 mm with internal 3500 mm, 230 mm walls, internal clear 3270 mm each room, partition with door P1, door D 1200 × 2100, D1 1000 × 2100, window W 1500 × 1200, W1 1200 × 1200 (as printed '15400×1200'). Section X-X: 600 mm roof projection, 18 mm screed over 2 layers of tarfelt, roof slab, window 3270 wide, sill/lintel levels 2100 and 2400, DPC, plinth with 3 cm cement sand (1:1) pointing over 36 cement concrete (1:2:4), 75 thick brick bats soling, 150 sand filling, foundation PCC (1:3:6) 770 mm wide with 150/250/150 mm layers.]

Reading of the drawing

Two rooms of 3.27 m × 3.27 m clear side by side, 230 mm walls (3 × 0.23 + 2 × 3.27 = 7.23 m; 3.27 + 2 × 0.23 = 3.73 m). Centre-line length of outer walls = 2[(7.23 − 0.23) + (3.73 − 0.23)] = 21.00 m. The central partition is 3.27 + 0.23 = 3.50 m between the outer-wall centre lines; at its two T-junctions it is shortened by half the width of the outer-wall item at each end, so it is 3.50 − 0.77 = 2.73 m for the trench and PCC, and 3.50 − 0.23 = 3.27 m for the wall.

Foundation profile assumed from the section: PCC 1:3:6, 0.77 m wide × 0.15 m; brick step 0.69 m × 0.25 m; step 0.46 m × 0.15 m; 230 mm wall, trench depth 0.80 m; plinth 0.45 m above GL. Wall height above plinth (floor to slab soffit) = 2.4 m. Openings assumed: D 1.2 × 2.1 (1 no.), D1 1.0 × 2.1 (1 no., partition), W 1.5 × 1.2 (2 nos.), W1 1.2 × 1.2 (1 no.).

a) Earthwork in excavation in foundation

Item	No.	L (m)	B (m)	H/D (m)	Qty (m³)
Trench, outer walls	1	21.000	0.770	0.800	12.936
Trench, partition (3.50 − 0.77)	1	2.730	0.770	0.800	1.682
Total					14.618

b) PCC (1:3:6) in foundation

Item	No.	L (m)	B (m)	H/D (m)	Qty (m³)
PCC 1:3:6, outer walls	1	21.000	0.770	0.150	2.426
PCC 1:3:6, partition	1	2.730	0.770	0.150	0.315
Total					2.741

c) Brickwork in 1:6 c.s. in superstructure wall

Item	No.	L (m)	B (m)	H/D (m)	Qty (m³)
Wall 0.23 × 2.4 above plinth (21.00 + 3.27)	1	24.270	0.230	2.400	13.397
Deduct D 1.2×2.1	-1	1.200	0.230	2.100	-0.580
Deduct D1 1.0×2.1	-1	1.000	0.230	2.100	-0.483
Deduct W 1.5×1.2	-2	1.500	0.230	1.200	-0.828
Deduct W1 1.2×1.2	-1	1.200	0.230	1.200	-0.331
Total					11.175

d) Wood work for door and window frames

Frame section assumed 100 × 75 mm (doors have no sill member).

Frame	No.	L (m)	B (m)	H/D (m)	Qty (m³)
Frame D (2×2.1 + 1×1.2)	1	5.400	0.100	0.075	0.0405
Frame D1 (2×2.1 + 1×1.0)	1	5.200	0.100	0.075	0.0390
Frame W (2×1.2 + 2×1.5)	2	5.400	0.100	0.075	0.0810
Frame W1 (2×1.2 + 2×1.2)	1	4.800	0.100	0.075	0.0360
Total					0.1965

Answer: Excavation 14.62 m³; PCC 2.741 m³; superstructure brickwork 11.18 m³; frame timber 0.197 m³.

✓ Answer checked by Claude Opus 5.5 (high effort)

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