Wall Plaster & It’s Precautions

                          

Plaster is application of cement mortar in a uniform thickness. The proportion of mortar most commonly used. Now days, some ready made plastering mortar is available. It have some additional benefits. For example: anti- dampness property, anti – efflorescent properties etc. As well as cost is almost similar to the normal cement mortar plastering.

01. Specification of Plaster

Here are world wide different standard of plastering work specification. We are specifying Indian standard (BIS code) list. 

1. IS 383 specification for coarse and fine aggregates for natural sources for concrete.
2. IS 1542 specification for sand for plaster.
3. IS 2645 specification for integral cement waterproofing compound.
4. IS 8112 specification for 43 grade OPC.
5. IS 269 specification for 33 grade OPC.
6. IS 1489 specification for Portland Pozzolana cement.

02. What are the Sequences of Works carried out Before Starting the Plastering Work?

Internal brick masonry must be completed before commencing the internal plastering work. In the case of external plastering work, you should have to finish the periphery brickwork of each floor first. The outside plastering work always starts from the top of the building and finished at the bottom, and ceiling plaster should be completed before commencement of wall plastering.

03. How to Manage the Materials of Plastering Work?

It is measured in area. The quantity of plastering works measured in the square meter of area. It is measured by multiplying length and height of the wall surface. The approximate materials used for 12 mm thickness in C: M 1:3 is 7.5 kg cement, and 0.015m3 sand is required per 1 m2 of plaster.The approximate materials used for 20 mm thickness in C: M 1:3 is 11.5 kg cement, and 0.024m3 sand is required per 1 m2of plaster.

04. Which Precautions should be taken during the Workmanship of Plastering Work?

• Plastering work must be started with adequate surface preparation. The joint of the brick wall should be racked out correctly. Dust and loose mortar should be removed by brushing and scrapping. The surface should then be thoroughly washed with water, cleaned and kept wet before plastering is commenced.
• Sand should be screened through the sieve, and proportioning of cement mortar should be as per specification.

Mortar should be used shortly after mixing, and excessive amounts of mortar should not be mixed at a time. It must be used within 30 minutes of adding water, if delayed either reject the mix or add adequate extra cement.

• 150 mm wide chicken mesh should be provided between the junction of column/beam and wall to prevent the cracks. Nails should be used 150 mm center to center for fixing chicken mesh.
• In the case of interior cement plaster with floating coat of neat cement, the quantity of cement applied for floating coat must be 1 Kg per Sqm.

• In the case of exterior plaster of 18 mm thickness, it must be done in two coats. The first layer of 12mm thick should be left rough and furrowed 2 mm deep with scratching tool and then apply 6 mm thick second layer.
• The surface should be finished off true with a trowel and wooden float to give a smooth surface.
• It should frequently be tested as the work proceeds with a true straight edge not less than 2.5 m long and with plumb bobs. Always check line, level and plumb of the vertical or horizontal surface, edge.

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