Method Statement for Dry-Mix Cement and Sand Plastering

1. Purpose

The purpose of this method statement is to outline the procedures and best practices for applying dry-mix cement and sand plaster on various surfaces, ensuring quality, safety, and adherence to project specifications.

2. Scope of Work

This method statement covers the application of dry-mix cement and sand plaster on concrete, masonry, and other suitable surfaces, for both internal and external applications.

3. Materials

Dry-Mix Cement and Sand Plaster: A pre-blended mixture of cement, sand, and additives, supplied in bags or bulk, conforming to relevant standards.
Water: Clean and potable, free from impurities.
Bonding Agent: For enhanced adhesion on smooth or dense surfaces, as required.
Plaster Mesh: Galvanized or fiberglass mesh for reinforcement at joints or over large areas prone to cracking (optional).

4. Tools & Equipment

Trowels (steel and wooden floats)
Hawk
Spirit level
Plumb bob
Straight edge
Buckets for mixing (if manual mixing is required)
Mechanical mixer or drill with mixing paddle
Measuring tape
Brushes and sponges
Scaffolding or ladders (if required)
Spray equipment (if plaster is applied using a machine)

5. Safety Precautions

Ensure all workers wear appropriate personal protective equipment (PPE), including safety helmets, gloves, goggles, and safety boots.
Ensure scaffolding and ladders are secure when working at heights.
Provide adequate ventilation in enclosed spaces to avoid inhalation of dust.
Handle dry-mix plaster with care to prevent skin irritation and respiratory issues.

6. Preparation

Surface Preparation:

Inspect the surface to ensure it is clean, dry, and free from dust, oil, grease, and loose particles.
Roughen smooth surfaces using a wire brush or chisel to provide a key for the plaster. On concrete or precast surfaces, applying a bonding agent may be necessary.
Fill any cracks or holes with a suitable filler material and ensure the surface is even.
Dampen the surface with clean water before plastering. The surface should be uniformly moist but not saturated to prevent rapid absorption of water from the plaster.

Setting Out Levels:

Establish and mark reference points and levels using a plumb bob, spirit level, and chalk lines to ensure even application.
Install guide screeds as necessary to maintain the desired plaster thickness.

7. Mixing

Dry-Mix Preparation:

Follow the manufacturer’s instructions for mixing the dry-mix plaster. Typically, add the dry-mix material to a clean container.
Gradually add water to the dry mix while stirring continuously. Use a mechanical mixer or drill with a mixing paddle to ensure a consistent, lump-free mixture.
Mix until the plaster reaches a smooth, workable consistency. Avoid adding excessive water, as this can weaken the plaster.

8. Application Procedure

First Coat (Scratch Coat):

Apply the first coat of dry-mix plaster, usually 10 to 12 mm thick, using a trowel. Start from the bottom and work upwards.
Use a straight edge to level the plaster and remove any excess material.
While the plaster is still fresh, scratch the surface with a notched trowel or comb to create a rough texture, which will provide a key for the subsequent coat.
Allow the scratch coat to cure for at least 24 hours, keeping it moist to prevent premature drying and cracking.

Second Coat (Finish Coat):

After the scratch coat has cured, apply the second coat of dry-mix plaster, typically 6 to 8 mm thick.
Use a straight edge and spirit level to ensure the surface is even and smooth.
Smooth the surface using a wooden float for a medium finish or a steel trowel for a finer finish, depending on the desired texture.
In areas prone to cracking or on large spans, consider embedding plaster mesh within the first coat to provide additional reinforcement.

Machine Application (If Applicable):

If using spray equipment, adjust the machine settings according to the manufacturer’s guidelines to achieve the desired thickness and finish.
Spray the plaster evenly across the surface and immediately follow with a straight edge to level the material.

9. Finishing

Final Smoothing:

After the plaster has been applied and is partially set, use a steel trowel to achieve a smooth finish.
For textured finishes, use a sponge float or brush while the plaster is still workable.

Curing:

Curing is essential to prevent cracks and ensure the plaster reaches its full strength. Begin curing after 24 hours by lightly spraying water on the plastered surface.
Continue curing by keeping the plaster damp for 7 days, especially in hot or dry conditions, to prevent it from drying too quickly.

10. Quality Control

Thickness Verification: Use a straight edge and spirit level to verify that the plaster thickness meets the specified requirements.
Surface Evenness: Ensure the plastered surface is even, smooth, and free from undulations.
Adhesion Testing: Tap the surface lightly to check for hollow spots, indicating potential adhesion issues.
Finish Inspection: Check the surface for smoothness, consistency, and absence of defects such as cracks or voids.

11. Clean-Up

Clean all tools and equipment immediately after use to prevent the plaster from hardening on them.
Remove any excess plaster from adjacent surfaces while it is still wet.
Ensure the work area is clean and free from debris.

12. Completion & Handover

Conduct a final inspection to ensure that the plastering work complies with the project specifications and quality standards.
Provide documentation confirming the completion of the plastering work, noting any deviations or corrective actions taken during the process.
Hand over the plastered surfaces, ensuring they are ready for any subsequent treatments, such as painting or finishing.

Conclusion

This method statement provides a detailed procedure for applying dry-mix cement and sand plaster, ensuring high-quality results through proper preparation, mixing, application, and curing. Following these steps will result in a durable, aesthetically pleasing plaster finish that meets project requirements and stands the test of time.