Calculating the the volume of block masonry for a shed./ Estimation & costing of a shed ( part 3 ).

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Let us make a footing base in 1.33 ft. (16") width and 0.5 ft. (6") in depth using concrete blocks.

Here, footing width = 1.33 ft.(16"), depth = 0.5 ft.(6"),

Volume of block masonry for foundation

      = length × width × depth 

From the above diagram, you can observe that half of the foundation width (0.66 ft.) falls on either side of the wall centerline.

So, the total length of the footing masonry

    = 2nos.× long side + 2nos. × short side.

    = (2nos.×( 9.5 ft. +(0.66ft ×2 nos.))) + (2 nos.× ( 7.5 ft.- (0.66ft.× 2nos.)))

    = ( 2nos.× 10.83 ft.) + (2 nos. × 6.17 ft.)

    = 21.66ft + 12.34 ft.

    = 34 ft.

1. The volume of footing block masonry

  v1 = 34 ft. × 1.33 ft. × 0.5 ft. 

       = 22.61 cu.ft.

The volume of block masonry for the substructure & superstructure: 

 The total depth of the block masonry up to plinth level 

    = depth below ground level + depth above ground level up to plinth

    = (0.92 ft.- 0.5 ft) + 1 ft.

        ( Taken from above-given drawings )

     = 1.42 ft.

2. Block masonry volume up to plinth level

 v2 = length × depth × thickness

     = ((2 nos × long wall length )+(2 nos. × short wall length )) × depth × thickness

     = ((2nos. × 10 ft ) +( 2 nos.× 7 ft. ))  ×1.42 ft. × 0.5 ft.

     = 34 ft. × 1.42 ft.× 0.5 ft.

     = 24.14 cu.ft.

3. Block masonry volume above plinth level

v3  = front wall volume + back wall volume +( 2 nos.× side walls volume)

      = (10 ft.× 8 ft.× 0.5 ft.) + ( 10 ft.× 9 ft. × 0.5 ft.) + 2 nos. ( 7 ft. × 8.5 ft. × 0.5 ft.)

                        (height of side wall is average of 9 ft. & 8ft. i.e. 8.5 ft.) ↑

     = 40 + 45 + 59.5 

     = 144.5 cu.ft.

4. Deduct door & window from block masonry

v4 = door size vol. + window size vol.

     = (2.5ft.× 6.5 ft.× 0.5 ft. )+( 3ft. × 3.5 ft.× 0.5 ft. )

     = 8.125 + 5.25

     = 13.375 cu.ft.

The total volume of the block masonry 

        = (v1 + v2 +v3) - v4

       = (22.61 cu.ft. + 24.14 cu.ft. + 144.5 cu. ft.) - 13.375 cu.ft.

       = 191.25 cu.ft.- 13.375 cu.ft.

      = 177.875 cu.ft.

The number of concrete blocks (6"× 8"×16")  required to build the shed

     = 210 nos. × (177.875 cu ft. ÷ 100 cu ft. )

     = 373.53 blocks. 

By rounding off, the no. of blocks = 374 nos.

Note: Coping & lintels are not deducted from the masonry, and hence they were not calculated separately.

The number of cement bags required for the masonry

  = 1.038 bags  × (177.875 cu ft. ÷ 100 cu ft. )

   = 1.85 bags.

The volume of sand required for the masonry

   = 7.634 cu ft. × (177.875 cu ft. ÷ 100 cu ft. )

  = 13.578 cu ft.

Note: The ratio calculated above is taken from the article "Calculating the quantity of materials in a 100 cubic ft. block wall".

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