Sep 3, 2021

External Plaster Work - Standard Work Procedure

External Plaster Work


Introduction:

This standard operating procedure enumerates the scope of External Plasterwork to be executed in the Tower area as specified in the approved drawings and at places when instructed by the Tower-in-charge.

Responsibility: 

The respective Tower-in-charge is responsible to execute the work as per the procedure.

Safety & protection:

Use double scaffolding always and ensure the scaffolding is adequately braced with the permanent structure, for working at heights. Unless it is tagged as safe for use by Safety Officer no work should be carried out on that scaffold area.

PPEs like safety belts at height, helmets, safety goggles, etc. should be used properly. 
Ensure the working area is kept clean for easy access and protect edges of opening by barricading etc while working.

Inspect the scaffolding before starting work.

Proper illumination is to be provided during the work if required.

Educate the workmen through a pep-talk meeting. 
 

Preparatory works:

Complete all external works like Check certificate provided by Safety Officer for scaffolding.

Filling of all vertical and horizontal joints of the block with AAC Block Adhesive.

Filling of the gap between block top and RCC member bottom area with cement mortar and apply non shrink grout on the surface.

Fixing of fiber mesh on all Block to RCC Joints.

Fix level pads (dhada), by tying line thread, from top to bottom, at corners and intermediate distances and it should be checked by the concerned engineer.

Ensure hacking on AAC block and RCC Surface.

Electrical and plumbing fixtures are checked for their alignment.

 Work Method:

 Mortar Preparation:  

The mortar for plastering has to be prepared in a Tray or on metal sheets only. The sand has to be sieved for proper gradation.

The sand has to be washed to remove impurities like a mud if required, and sufficiently dried before plastering work is taken up.

In case wet sand is to be used, check for the quantity of water in a mortar and allow for bulkage of sand while mixing, for ensuring consistency of mortar.

Crush Sand and River Sand should be used in 50:50 proportions.

Do prepare the mortar in proportion as follows;

Bond Coat / Key Coat  1:4 (1 part Cement, 2 Part River Sand, and 2 parts Crush Sand) with waterproofing compound @ 150 ml Per bag of cement (BASF MaterEmaco 141) to be done in thickness 8 to 10 mm.

Finish  Coat  1:3 (1 part Cement, 1.5 Part River Sand and 1.5 parts Crush Sand) with 6mm fibers @ 100 grams per bag of cement ( Strongplast ) and waterproofing compound @ 150 ml Per bag of cement (BASF MaterEmaco 141) to be done in thickness of 12 to 15 mm.
Then do Dabba finish (sand face finish).

Do mix mortar which can be consumed within the next 2 hours.

Do add water to the dry mixed sand and binder (not otherwise).

Bond Coat / Key Coat

Do wet the surface to receive plaster one hour before, so that while starting plastering, the surface is skin dry.

Bond Coat / Key Coat shall be started from the top and worked downwards.

Curing should be done for min 3 Days.

 Finish  Coat

Do throw the mortar for an area coverable by the straight edge, both vertically and horizontally in one stretch.

Do level the surface using the straight edge.

Do float the surface and finish as per specification.

Do repeat this operation for the entire area in stages.

While proceeding with the work, do float and finish the joints in the I stage and then in subsequent stages properly. This is to ensure the stages, in plastering work, are not apparently visible.

Intermediately do check the surface for plumb, line, and level and make up all deficiencies.
If there are grooves in the design, then they should be made at the locations specified.

However, care should be taken to see that the depth of the groove does not cut the base coat or it will lead to leakage.

After making the groove it should be finished neatly with a paste of cement and waterproofing compound. Then do final finishing by brushing.

Do jambs finish in openings in line with internal plaster face or as per level pads and ensure right angles at the corner.

Ensure edge finishing around switchboards is done correctly.

In case of unavoidable situations where the scaffold needs to brace in-wall, the pocket should be sealed and match the plaster finish immediately after removing it.

Curing should be done for min. 7 Days.

After completion of plaster clean the area.

Dos and Do nots:

Do’s:

Do check thoroughly before and immediately after plastering, the line and levels.

Do check thoroughly before and immediately after plastering, the surface areas for unevenness, surface blemishes, etc so that all rectification (if required) can be carried out within the final setting time, without any additional costs.

Do cure the plastering well for the required number of days.

To restrict the access to areas where plastering is complete (This will ensure better protection of edges, corners, angles, etc).

To ensure all touch-ups are done neatly after pre-cast slabs are embedded in position, working platforms are inserted in position, sanitary fixtures are fitted (merging the surfaces being touched up with original surfaces).

Do stop the work preferably in corners, jambs, stoppers or at grooves, etc. This will avoid cracks at joints. To ensure these joints are finished neatly.

Do not:

Do not allow mortar mixing on the unclean areas and in large quantities.

Do not allow usage of partially set mortar.

Do not allow free sprinkling of dry cement in the mortar or on the surface being plastered, as this may cause uneven shrinkage and lead to the development of shrinkage cracks.

Do not mix different brands of cement in the same area as this will show the color difference (till plastered surfaces are covered with some other finish). 



Team
CBEC India

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