The standard size of a masonry brick is
Try it first: pick an option, then read the explanation.
Understanding Standard vs. Nominal Size
When discussing brick sizes, it's crucial to understand two key terms. This is a common point of confusion in exams.
- Standard Size (or Modular Size): This is the actual, manufactured dimension of a single brick before any mortar is applied.
- Nominal Size: This is the size of the brick *plus* the mortar joint surrounding it. In India, the standard mortar thickness is 1 cm (10 mm).
Detailed Analysis of the Options
B. 19 cm x 9 cm x 9 cm
This is the correct answer. The Bureau of Indian Standards (BIS) recommends a standard size for modular bricks as 19 cm x 9 cm x 9 cm. This is the actual size of the brick itself.
C. 20 cm x 10 cm x 10 cm
This is the nominal size of a standard Indian brick. It is calculated by adding the 1 cm mortar thickness to each dimension of the standard brick:
- Length: 19 cm (brick) + 1 cm (mortar) = 20 cm
- Width: 9 cm (brick) + 1 cm (mortar) = 10 cm
- Height: 9 cm (brick) + 1 cm (mortar) = 10 cm
While this is a very important dimension for masonry calculations, it is not the "standard size" of the brick itself.
A. 18 cm x 8 cm x 8 cm & D. 21 cm x 11 cm x 11 cm
These are incorrect dimensions for standard modular bricks in India. Different countries and regions may have "traditional" or non-standard bricks of various sizes, but these do not conform to the BIS standard.
Brick Sizes Around the World
It's interesting to note that standard brick sizes vary globally. Here are a few examples:
| Country | Standard Size (mm) | Standard Size (cm) |
|---|---|---|
| India (BIS) | 190 x 90 x 90 | 19 x 9 x 9 |
| Nepal (NBC) | 240 x 115 x 57 | 24 x 11.5 x 5.7 |
| Philippines | 215 x 102.5 x 65 | 21.5 x 10.25 x 6.5 |
| United Kingdom | 215 x 102.5 x 65 | 21.5 x 10.25 x 6.5 |
Study Tips
- Standard = Stand-alone: Think of the "Standard" size as the size of the brick when it's standing alone, before it's put in a wall.
- Nominal = Name Only (with mortar): The "Nominal" size is the size "in name only" for calculation purposes, and it always includes the mortar.
- The 1 cm Rule: For Indian standards, just remember to add 1 cm to each dimension of the standard size (19x9x9) to get the nominal size (20x10x10).