The plan of a building is in the form of a rectangle with center line dimensions of outer walls as 12.7 m × 15.7 m. If the thickness of the wall in superstructure is 0.30 m, then its plinth area (in m2) is
- A199
- B201
- C208Correct
- D210
Solution
Concept
Plinth area calculation from centerline dimensions
Formula
Plinth Area = (Lcl + t) × (Bcl + t)
Step-by-step solution
1. Out-to-out length = Centerline length + Wall thickness = 15.7 + 0.30 = 16.0 m. 2. Out-to-out width = Centerline width + Wall thickness = 12.7 + 0.30 = 13.0 m. 3. Plinth area = Out-to-out length × Out-to-out width. 4. Plinth area = 16.0 m × 13.0 m = 208 m². Answer: C
Explanation
Plinth area is the built-up covered area of a building measured along the outer dimensions of the walls at plinth level. For a rectangular building with centerline dimensions 12.7 m × 15.7 m and wall thickness 0.30 m, the out-to-out dimensions are (12.7 + 0.30) = 13.0 m and (15.7 + 0.30) = 16.0 m. The plinth area is 13.0 m × 16.0 m = 208 m².
Why the other options are wrong
A) 199 m² results from multiplying unadjusted centerline dimensions (12.7 × 15.7 = 199.39 m²). B) 201 m² results from adding wall thickness along only one axis. D) 210 m² represents an overestimation error in adding wall thickness.
Shortcut
Outer dimension = Centerline + 1 wall thickness; Area = 16 × 13 = 208 m².
Common mistake
Multiplying the centerline dimensions directly (12.7 × 15.7 = 199.39 ≈ 199 m²) or adding wall thickness only to one side instead of both outer faces.
Correct answer: C) 208