Specifications used for the Plastering Work

Procedure of Plastering Work

1. Preparation of Surface for Plastering

1. Keep all the mortar joints of the wall rough, in order to ensure good bonding to hold the plaster.
2. Roughen the entire wall to be plastered.
3. Clean all the joints and surfaces of the wall with a wire brush. There should not be any oil or grease left on the wall surface.
4. If there are any cavities or holes on the surface, then fill it in advance with appropriate material.
5. If the surface is smooth or the wall to be plastered is an old one, then rake out the mortar joint to a depth of at least 12 mm to give a better bonding to the plaster.
6. Wet the mortar joints and the entire wall to be plastered. Keep it wet for at least 6 hours before applying cement plaster.
7. If the projection on the wall surface is more than 12 mm, chip it off, so as to obtain a uniform surface. This will reduce the consumption of mortar.

2. Groundwork for Plaster

1. In order to get a uniform thickness of plastering throughout the wall surface, first, fix the dots on the wall. A dot means a patch of plaster of size 15 mm * 15 mm and having a thickness of about 10 mm.
2. Firstly, the dots are fixed on the wall horizontally and then vertically at a distance of about 2 meters covering the entire wall surface.
3. Check the verticality of dots, one over the other, by means of plumb-bob.
4. After fixing the dots, the vertical strips of plaster, known as screeds are formed in between the dots. These screeds serve as the gauges for maintaining an even thickness of plaster being applied.

3. Applying Under Coat or Base Coat

1. In the case of brick masonry, the thickness of the first coat plaster is in general 12 mm and in the case of concrete masonry, this thickness varies from 9 to 15 mm.
2. The ratio of cement and sand for first coat plaster varies from 1:3 to 1:6.
3. Apply the first coat of plaster between the spaces formed by the screeds on the wall surface. This is done by means of a trowel.
4. Level the surface by means of flat wooden floats and wooden straight edges.
5. After leveling, allow the first coat to set, but not to dry, and then roughen it with a scratching tool to form a key to hold the second coat of plaster.

4. Applying Finishing Coat

1. The thickness of the second coat or finishing coat may vary between 2 to 3 mm.
2. The ratio of cement and sand for the second coat of plaster varies from 1:4 to 1:6.
3. Before applying the second coat, dampen the first coat evenly.
4. Apply the finishing coat with wooden floats to a true even surface and using a steel trowel give it a finishing touch.
5. As far as possible, the finishing coat should be applied to start from the top towards the bottom and completed in one operation to eliminate jointing marks.

5. Curing of Plastering works

1. After completion of the plastering work, the finished wall surface is kept wet by sprinkling water for at least 7 days in order to develop strength and hardness.
2. Gunny bags or other materials are used to keep the plastered work surface wet in external works.
3. Improper curing may lead to cracks formation or efflorescence in plasterwork.

6. Care be taken after Completion of Plaster Work

• Cleaning of doors or frames and floor areas is necessary after the completion of work.
• Curing should be started as soon as the plaster has hardened sufficiently and must be cured for at least 7 days.
• Curing shall commence, 24 hours after the plaster is laid.