Method of measurement of building and civil engineering works, Part 13: Whitewashing, colour washing, distempering and painting building surfaces
1994 Edition

Per IS 1200 Part 13, openings and attachments are handled as follows:

For openings up to 0.5 m², no deductions are made for ends of structural members or openings, nor are additions made for reveals or similar features.

For openings larger than 0.5 m² and up to 3 m², deductions are limited to the opening area itself with no additions for reveals. The deduction depends on the finish on both faces: if both sides have the same finish, deduction is applied only on one face; if finishes differ, deduction is on the side with the smaller reveal, or split equally if reveals are equal. Door frames that match or exceed wall thickness require full deduction on both faces.

For openings exceeding 3 m², the opening area is deducted and reveals, jambs, and soffits are measured separately and added.

Attachments like casings, pipes, conduits, and wiring are not deducted.

This methodology ensures that surface measurements accurately reflect the work to be finished.

IS 1200 Part 13 requires inclusion of essential surface preparation activities within the main measurement item. These preparatory works comprise brooming, wire brushing with steel brushes, scraping off loose material, washing, and rubbing down surfaces to ensure cleanliness and suitability for finishing.

These preparatory actions apply to both new surfaces and primary coats and must be described in detail. Additionally, surface measurements should indicate whether areas are recorded as flat or wrapped (girthed) around corners.

Uneven surfaces require conversion to equivalent plain areas using prescribed percentage increments based on surface texture, ensuring accurate quantity estimation.

The standard provides specific conversion factors to account for textured or uneven surfaces by increasing the measured flat area to an equivalent plain area, facilitating uniform measurement. For example, external walls with recessed or raised pointing incur a 20% increase, sand face plaster up to 4 mm size increases area by 50%, rough cast plaster with stone aggregate up to 10 mm doubles the area (100% increase), pebble dash finish beyond 10 mm more than triples the area (275% increase), and sponge finished plaster is adjusted by 25%.

This approach ensures fair assessment of paint quantities needed for these surface types by compensating for their additional surface area.

According to IS 1200 Part 13, surfaces previously treated are measured separately and distinctly identified in the bill of quantities. Preparatory work on such old treated surfaces, including priming, scrapping, washing, and treatments for disinfection or removal of contaminants, must be described and included within the main item.

In contrast, preparatory activities on new surfaces and primary coatings are included in the main item description. Measurements should specify whether surfaces are flat or girthed, and uneven surfaces are converted using the standard percentage increases to equivalent plain areas.

Materials and processes related to old surface preparation are measured separately with detailed descriptions to ensure clarity in documentation and billing.

IS 1200 Part 13 mandates that the number of coats for any decorative finish, such as whitewash, colour wash, distemper, or paint, be explicitly indicated in the item description. Each coat is measured individually in accordance with the specification.

The standard classifies decorative finishes into categories like whitewash or colour wash, non-washable and washable distempers, waterproof paints, chalk whiting on cloth or hessian, linseed oil and cement coatings on metal surfaces, and cement slurry washes.

Measurements should specify if surface areas are flat or girthed, and for uneven surfaces, conversion to equivalent plain areas is done using defined percentage increases. This ensures accurate quantification and cost estimation for each type and number of coats applied.