The calculation of deductions in plastering and painting works measurement has always been a challenge for site engineers.
In this article, we discuss how to calculate the deductions in plastering and painting works as per IS Code.
General Measurement of Plastering and Painting
The plastering and painting works shall be measured in square meter and recorded up to second decimal.
- Dimensions shall be measured to the nearest 0·01 m, and
- Areas of individual items shall be worked out to the nearest 0.01 m2.
Deductions in Plastering and Painting
The deductions in the plastering and painting works are divided into three categories:
1. Openings not exceeding 0.5 m2
For jambs, soffits, sills, etc. openings not exceeding 0.5 m2 each in area and for ends of joists, beams, posts, girders, steps, etc., not exceeding 0.5 m2 each in area:
No deduction shall be made for ends of joists, beams, posts, etc., and openings not exceeding 0.5 m2 each, and no addition shall be made for reveals, jambs, soffits, sills, CLC, of these openings nor finish around ends of joists, beams, posts, etc.
2. Openings exceeding 0.5 m2 and not exceeding 3 m2
Deductions for openings exceeding 0.5 m2 but not exceeding 3 m2 each shall be made as follows and no addition shall be made for reveals. jambs, soffits, sills, etc, of these openings:
- When both faces of the wall are provided with the same finish, deduction shall be made for only one face.
- When each face of the wall is provided with a different finish, deduction shall be made for that side on which the width of the reveal is less than that of the other side; but no deduction shall be made on the other side where the width of reveals on both faces of the wall are equal, or deduction of 50 percent of the area of opening on each face shall be made from the area of finish.
- When only one face is treated and the other face is not treated, full deduction shall be made if the width of reveal on the treated side is less than that on the untreated side, but if the width of the reveal is equal or more than that on the untreated side, neither deduction for the opening nor addition for reveals, jambs, soffits, sills, etc, shall be made.
- When the width of the door frame is equal to the thickness of the wall or is projecting beyond the thickness of the wall, a full deduction for opening shall be made from each face of the wall.
- When the reveal is only on one side, a full deduction for the face having no reveal shall be made and a deduction of 50 percent of the opening shall be made for the face having reveal.
3. Opening exceeding 3 m2
In case of openings of areas above 3 m2 each, deductions shall be made for openings, but jambs, soffits, and reveals shall be measured.