Mode of Measurement as per IS 1200 (PART-12) | Measurement of Plaster Work| BY CIVIL GURUJI
Channel: Civil Engineers Training Institute
Date: 2020-08-13

Mode of Measurement as per IS 1200 (PART-12) | Measurement of Plaster Work| BY CIVIL GURUJI




Plaster, a pasty composition (as of lime or gypsum, water, and sand) that hardens on drying and is used for coating walls, ceilings, and partitions.
Plasterwork is construction or ornamentation done with plaster, such as a layer of plaster on an interior or exterior wall structure, or plaster decorative moldings on ceilings or walls. ... The process of creating plasterwork, called plastering or rendering, has been used in building construction for centuries
Tools and materials include trowels, floats, hammers, screeds, a hawk, scratching tools, utility knives, laths, lath nails, lime, sand, hair, plaster of Paris, a variety of cements, and various ingredients to form color washes.
While most tools have remained unchanged over the centuries, developments in modern materials have led to some changes. Trowels, originally constructed from steel, are now available in a polycarbonate material that allows the application of certain new, acrylic-based materials without staining the finish. Floats, traditionally made of timber (ideally straight-grained, knot-free, yellow pine), are often finished with a layer of sponge or expanded polystyrene.
 Methods :-
The first coat or rendering is from 1/2 to 3/4 inches thick, and is mixed in the proportions of from one part of cement to two of sand to one part to five of sand. The finishing or setting coat is about 3/16 inches thick, and is worked with a hand float on the surface of the rendering, which must first be well wetted.
External plastering
Stucco is a term loosely applied to nearly all kinds of external plastering, whether composed of lime or of cement. At the present time it has fallen into disfavor, but in the early part of the 19th century a great deal of this work was done. Cement has largely superseded lime for this work. The principal varieties of stucco are common, rough, trowelled and bastard. .
• Common stucco for external work is usually composed of one part hydraulic lime and three parts sand. The wall should be sufficiently rough to form a key and well wetted to prevent the moisture being absorbed from the plaster.
• Rough stucco is used to imitate stonework. It is worked with a hand float covered with rough felt (a stiff bristled brush can also be used), which forms a sand surface on the plaster. Lines are ruled before the stuff is set to represent the joints of stonework.
• Trowelled stucco, the finishing coat of this work, consists of three parts sand to two parts fine stuff. A very fine smooth surface is produced by means of the hand float.
• Bastard stucco is of similar composition, but less labor is expended on it. It is laid on in two coats with a skimming float, scoured off at once, and then trowelled.
• Colored stucco: lime stucco may be executed in colors, the desired tints being obtained by mixing with the lime various oxides. Black and grays are obtained by using forge ashes in varying proportions, greens by green enamel, reds by using litharge or red lead, and blues by mixing oxide or carbonate of copper with the other materials.
Main article: Roughcast

Plasters are applied in successive coats or layers on walls or lathing and gains its name from the number of these coats.
• One coat work is the coarsest and cheapest class of plastering, and is limited to inferior buildings, such as outhouses, where merely a rough coating is required to keep out the weather and draughts. This is described as render on brickwork, and lath and lay or lath and plaster one coat on studding.
• Two-coat work is often used for factories or warehouses and the less important rooms of residences. The first coat is of coarse stuff finished fair with the darby float and scoured. A thin coat of setting stuff is then laid on, and trowelled and brushed smooth. Two-coat work is described as render and set on walls, and lath, plaster and set, or lath, lay and set on laths.
• Three-coat work is usually specified for all good work. It consists, as its name implies, of three layers of material, and is described as render, float and set on walls and lath, plaster, float and set, or lath, lay, float and set, on lathwork. This makes a strong, straight, sanitary coating for walls and ceilings.
The process for three coat work is as follows:
• For the first coat a layer of well-haired coarse stuff, about 1 inch thick, is put on with the laying trowel. This is termed "pricking up" in London, and in America "scratch coating".