PLASTERING AND POINTING

INTRODUCTION:

Plastering is a method of coating the internal and external surfaces of walls and ceilings with cement mortar to achieve the required finish and aesthetic view to the bare R.C.C. and masonry surfaces. It protects the R.C.C. and masonry work from atmospheric effects and increases the durability.

FINISHES OF PLASTER:

1. Nerru finish
2. Sand faced
3. Rush plaster
4. Textured
5. Pebbled
6. Scrapped

The most commonly used finishes of plaster are nerru finish and sand faced finish. The nerru finished plaster is usually preferred for the surfaces, which are not directly exposed to weathering. The sand faced finish plaster is usually preferred for the surfaces, which are directly exposed to weathering.

REQUISITES FOR PLASTER WORK:

1. 1. Raw materials: – cement, sand, sanla, water and admixtures.
   2. Scaffolding materials.

PREPLANNING PROCESS:

1. 1. 1. After completion of brickwork, mark guideline dots (thiyya) in line, plumb diagonals and levels
      2. Complete concealed electrical piping and fixing of concealed boxes. The face of concealed boxes should be flush with plaster surface.
      3. The chiseled grooves for pipe and boxes should be finished with cement mortar.
      4. Fix the chicken mesh of 24 gauge and 12mm x 12mm size openings at all the joints of RCC, Masonry and for all electrical pipes.
      5. Dress all the surfaces to be plastered, with wire brush to remove the dust and loose particles.
      6. Preparation of freestanding scaffolding without holes through walls, with extra supports to the scaffolding shall be done.
      7. The surface to be plastered should be thoroughly watered.
      8. Sand should be sieved with screen of 10 holes/cm2.
      9. The trays for mixing of mortar and water storage tank shall be made available at workplace.

NEERU FINISH PLASTER:

Plaster work shall be started only after, all the prerequisites are fulfilled.

1. Mixing of mortar shall be done in a tray only.
2. Usually the mortar mix for internal plaster is: –
   
   1. Ceiling C.M. 1:4.
   2. Walls C.M.1: 6.
3. Cement and sand should be dry mixed properly before adding water.
4. Required quantity of water shall be added to achieve workable mix.
5. Admixtures, if any, shall be added to the mortar.
6. The mortar mix should be consumed within half an hour from mixing. The quantity of mortar shall be mixed accordingly.
7. Plastering work shall be started from ceiling, in C .M. 1:4 and then proceeded further with walls.
8. Trowelling of excessive C.M. is done for bringing the surface in level/line & plumb.
9. Finish all surfaces in level, line with respect to guideline dots.
10. Finish all the edges, corners and offsets in plumb, right angle and level.
11. Check sizes of all the openings for right angles.
12. Neeru shall be soaked atleast for two hours in water, before application

1. All the electrical points shall be finished neatly.
2. Desired quantity of cement shall be added in nerru for stiffness of edges.
3. A thin film of nerru shall be applied over the plastered surface and shall be finished smoothly.
4. The entire surface where dado tiles are to be fixed and shall be marked and made rough.Neeru shall not be applied on this surface.
5. The portion of the side walls, where the skirting of the tiles is to be fixed; shall not be plastered. If some mortar is stuck there, then it shall be scrapped properly upto 0.15 m from the top of the floor slab.
6. Curing should be done after 24 hours and carried out atleast for 14 days.

SAND FACED PLASTER:

1. Proper erection of scaffolding should be carried out with the help of skilled workmen. It should be erected on firm base and should have sufficient working space. It must be strong enough to sustain the moving load and should be designed for all safety aspects.
2. Mark the guide line dots in line, level and plumb.
3. Complete all the elevational brickwork. Fill all the gaps and holes if any, with rich cement mortar. Insert metal, at all junctions of R.C.C. & brickwork.
4. Fix chicken mesh of 24 gauge and 12mm x 12mm holes at all the joints of RCC and masonry.
5. Dress all the RCC/masonry surfaces for any projections.
6. Rub the entire surface to be plastered, with wire brush for removing dust and loose particles.
7. Surface to be plastered should be thoroughly watered.
8. Sand should be sieved with screen of 10 holes/cm2. For finishing coat, use the sand sieved from screen of 13 holes/cm2.
9. Confirm all the elevational and plastering details given by architect/ consultants.
10. Mixing of mortar to be done in a tray only.
11. Usually the mortar mix for external plaster is C.M.1: 4.
12. Cement and sand should be dry mixed properly before adding water.
13. Add required quantity of water to achieve workable mix. Admixtures shall be used, if specified.

The mortar mix should be consumed within half an hour and mix the quantity accordingly.

1. Ensure that tray for mixing of mortar and water storage tanks are available at work place.
2. Plastering work to be started from inside the parapet wall. Avoid the joints on top of parapet walls and proceed downwards.
3. Trowelling of excessive C.M. is done for bringing the surface in line & plumb.
4. Apply C.M.1:4 using sand sieved from sieve of 13 holes/cm2 for minimum thickness. Use sponge to achieve proper effect of sand faced plaster with uniform grains.
5. Finish the entire surface in line &plumb with respect to guideline dots.
6. Finish all the edges, corners and offsets in plumb, right angle and level.
7. Check all the openings for sizes and diagonals.
8. Clean all the mortar splashed on door frames, window frames, railing and all floors, thoroughly.
9. Curing should be done after 12 hours and shall be carried out atleast for 14 days.

PRECAUTIONS DURING THE EXTERNAL PLASTER:

1. Before starting plaster work, place plastic sheets/empty cement bags underneath the area to be plastered, to collect the falling mortar.
2. No supports for scaffolding should be taken from M.S. windows, frames, railings and grills etc. If unavoidable take supports by making holes at skirting level only.
3. Necessary precautions and safety measures are to be taken while removing the scaffolding, shifting of wooden planks and other scaffolding material.
4. All the workers working near the scaffolding area should wear helmet and safety belts. Safety belts to be tightened to firm supports only.
5. Fill the pocket holes of scaffolding supports with well soaked bricks and rich cement mortar with proper compaction and finish on the external as well as internal surfaces..
6. Utmost care should be taken to cure soffits of chajjas, cantilever portion, hidden portions etc. Refer Sketches for Various Plaster Details of chajja with drip mould :-

MISCELENEAOUS PLASTER WORK:

1. Butt finish: – It is a process of plastering the surface in between skirting top and previously left plaster, Necessary care shall be taken to match the surfaces. Proper curing and cleaning shall be carried out.
2. Minor repairs: – All minor repairs shall be carried out by skilled mason only. The curing of the repaired works shall be done properly.

POINTING:

Pointing is a process adopted to protect the joints in the masonry from atmospheric conditions. It also improves the asthetic view of the masonry walls.

Types of Pointing: –

1. Raised pointing
2. Sunk pointing
3. Flush pointing
4. Vee pointing

WORK PROCESS OF POINTING:

1. Rake all the joints for U.C.R. 25mm deep & 20 mm deep for brick masonry.
2. Remove all the loose mortar & cleaning the joints.
3. Watering to the joints to be done.
4. Filling & finishing of joints as per designed type of pointing with cement mortar to be done.
5. Curing for 7 days to be done