Specification for Plastering of Brick Wall

Following specification should be followed for plastering of brick wall using cement mortar or lime mortar.

Preparation

1. The joints of the brick work shall be raked out to a depth of 18 mm (3/4″).
2. Surface of the wall shall be washed and kept wet for two days before plastering.

Mortar Preparation

1. The materials of mortar, cement and sand or lime and surkhi or sand, or kankar lime as specified should be of standard specification.
2. The materials or mortar shall be first dry mixed by measuring with boxes to have the required proportion (as specified) and then water added slowly and gradually and mixed thoroughly.

Mortar Proportions

Different proportions of mortar which may be used for plastering –

1. Cement sand mortar – 1:3, 1:4, 1:5, 1:6
2. Cement, lime, sand mortar – 1:1:6,
3. Lime Surkhi or sand mortar – 1:1 , 1:2
4. Kankar lime mortar – Kankar lime alone
5. For ceiling plastering : 1:3 cement mortar with coarse sand is generally used.

Cement, line and sand mortar is slow setting and has better workability than cement sand mortar.

Plastering Procedure

1. The thickness of plastering shall be as specified usually 12 mm (1/2″) applied in two or three coats.
2. To ensure uniform thickness of plaster, patches of 15 cm x 15 cm (6″) strips  1 meter apart or 10 cm (4″) wide plaster shall be applied first at about 2 meters apart to act as guide.
3. First mortar shall be dashed and pressed over the surface and then brought to a true smooth and uniform surface by means of float and trowel.
4. External plastering shall be started from top and worked down towards floor.
5. Internal plastering shall be started wherever the building frame is ready and centering of the roof slabs have been removed.
6. Ceiling plastering shall be completed before starting of wall plaster.
7. All corners and edges shall be rounded.
8. Plastered surface shall be kept wet for 10 days.
9. Surface shall be protected from rain, sun, frost etc.

Plastering Coats

For ideal work, the plastering should be applied in three coats.

1. Rendering or first Coat : 10 mm.
2. Floating or second coat : 10 mm to 6 mm.
3. Finishing coat : 5 to 6 mm.
4. Total thickness of minimum 20 mm (3/4″).

1. The first coat shall be applied on the prepared, raked, cleaned and wetted surface by dashing the mortar and floated roughly with wooden float. It shall be kept damp for at least 2 days.
2. When the first coat has sufficiently set, the surface shall be wetted and a second coat of plaster shall be applied and brought to true even surface and then lightly roughened with a wooden float to provide bond for the finished coat. The second coat shall be kept damp for at least two days and then allowed to dry.
3. The finishing coat shall then be applied on the wetted surface of the second coat and finished smooth to true even surface by float and trowel.

Incomplete Plastering at the end of the day

1. The work shall be tested frequently with a straight edge and plumb bob.
2. At the ed of the day , the plaster shall be left cut clean to line.
3. When the next day’s plastering is started, the edge of the old work shall be scrapped, cleaned and wetted with cement slurry.
4. At the end of the day, the plastering shall be closed on the body of the wall and not nearer than 15 cm to any corner.

Curing

1. Curing shall be started as soon as the plaster has hardened sufficiently not tb be damaged when watered.
2. The plaster shall be kept wet for at least 10 days.

Defective Plaster

Any defective plaster shall be cut to rectangular shape and replaced.

Final Surface

If specified, the final surface shall be given special finishing textures, as Scaped textures, Canvas Textures, Cork-float finish, Wavy combed finish, Concentric arc finish etc. with the required tools by engaging an expert worker in profession.