Plastering with cement mortar requires a rate analysis, which involves estimating the quantity of materials needed, such as cement, sand, and water for various grades of mortar. The grades of mortar used for plastering are typically the same as those used in masonry work. These grades include 1:2, 1:4, 1:6, 1:8, and others.
The quantity of cement and sand needed for mortar is determined by calculating the volume of mortar required for plastering. This calculation is based on the thickness of the plastering surface and the surface area of the structural member.
The most common grade of mortar used for plastering work is 1:6. To calculate the quantity of cement and sand needed for this grade of mortar, it is necessary to determine the volume of mortar required for plastering. This calculation takes into account the thickness of the plastering surface and the surface area of the structural member.
In order to plaster a wall, several calculations must be made to determine the quantity of materials required and the labor costs involved. For example, if a wall is 2 meters long and 1.5 meters wide, with a thickness of 20mm, two layers of plaster of 10mm each will be required. The total quantity of cement mortar needed for this will be 0.06m3.
Once the quantity of cement and sand required is calculated using the rate analysis of cement mortar, the labor costs can be determined. The coefficients of labor for plastering work are taken from the Rate Analysis by CPWD. The cost of mixing the calculated quantity of mortar is fixed, but the cost of applying the mortar varies depending on the number of layers required.
The coefficients for mason and labor per m2 area per layer of plaster are as follows: Mason – 0.07435 days, Labors – 0.0929 days, and Bhishti – 0.0929 days (who carries materials and water for mixing). These coefficients are then multiplied by the quantity of cement mortar required and the number of layers needed.
The number of days required for the mason, labors, and Bhishti is calculated by multiplying the coefficients by the number of layers and the surface area. For example, for two layers of plaster on a 1.5m x 2m wall, the mason would require 0.44610 days, and both labor and Bhishti would require 0.5574 + 0.0126 and 0.5574 + 0.005574 days, respectively.
The daily wages of the masons and labors are then multiplied by the number of days required to get the total labor cost. An excel sheet can be used to calculate the rate analysis of plastering.