Thumb rule - How many bricks are in 1 CFT? - LCETED -lceted LCETED INSTITUTE FOR CIVIL ENGINEERS

## Feb 23, 2022

Thumb rule - How to calculate the number of Bricks per CFT – LCETED

In this article, we explained about thumb rule calculation for brickwork and bricks needed for Cubic feet – CFT, before we are going to calculation we have to know the size of the brick to proceed further

SIZE OF THE BRICK

Generally, four standard-sized bricks are used in India.

Which are,

Modular Brick / Metric Bricks – 7.48” x 3.54” x 3.54” or 190 x 90 x 90 mm (These are machine-made bricks)

Non-Modular Bricks – 9″ x 4.33″ x 2.75″ or 230 mm x 110 mm x 70 mm

Conventional Bricks – 9″ x 4.33″ x 4.33″ or 230 x 110 x 110 mm

English Size Bricks – 9″ x 4.5″ x 3″ or 230 x 115 x 75 mm (It is usually used in India.)

There are other dimensions depending on the country. The brick weight must not exceed 3 kg.

In this calculation, we will use the English Bricks size

Let’s start,

Thumb Rule for Brick Calculation Per CFT

(OR)

How to calculate the number of Bricks per Cubic Feet (CFT)

4″ brick wall or single layer or half brick

Inches to Feet (into ft) = divide the length value by 12

Size of brick without mortar → 9″/12 × 4.5″/12 × 3″/12 = 0.75’×0.375’×0.25’

Volume of brick with mortar = 0.75’×0.375’×0.25’ = 0.0703 cft

The thickness of mortar = 0.4” to  0.6”

By adding the thickness of the mortar

Length of Bricks in meter (L) = 9” + 0.4” = 9.4” - 0.783’

Width of Bricks in meter (W) = 4.5” + 0.4” = 4.9” - 0.4083’

Thickness of Bricks in meter (T) = 3” + 0.4” = 3.4” - 0.283’

Size of the brick with mortar in feet → 0.783’ x 0.4083’ x 0.283’

No. of bricks in 1 cubic Feet (cft) = Volume of brickwork/ Volume of one brick with mortar.

Volume of brickwork = (Length x Width x depth) of the wall = 1 x 1 x1 = 1cft (to have find per cft)

The volume of a brick = Length of brick x Width of brick x depth of the brick

Volume of each Brick in CFT= L x W x H = 0.783’ x 0.4083’ x 0.283’ = 0.09047 cft

Therefore,

No. of bricks in 1 Cft = 1/0.09047 = 11.053 – 12nos

Consider the wastage percentage as 10% of bricks we will

No. of bricks in 1cft = 12 + 10% = 13.2nos/cft

Then,

No. of bricks with wastage per cubic feet= 13.2 – 14nos/cft

Thus, thumb rule formula:

No. of bricks in wall per Cubic Feet= (Area in Cft × 14).

How to Use This Thumb Rule?

Let’s explain,

How many bricks are there in 100cft?

Given data:

Area of the brick wall = 100cft

No. of bricks in wall per Cft= (Area in cft × 14).

Therefore,

No. of bricks in wall per 100 Cft = 100 x 14 = 1400 nos

How many bricks are there in 10’x 10’?

Size of the 9” brick wall = 10’ x 10’

The thickness of the wall = 9”/12 – 0.75’ (breadth)

Area of the brick wall = 10 x 10 x 0.75 = 75 cft

No. of bricks in wall per Cft = (Area in cft × 14).

No. of bricks in wall per Cft = 75 x 14 =1050nos

If you find