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.
