It is important to protect the walls inside your home. Plastering gives the surface of a wall a smoother look and increases its strength. A thin layer of plaster is applied to the surface of masonry. Plaster is a must for brick-built houses as it acts as a damp proof coat. A coat of plaster, when applied correctly, can smooth out any rough surfaces, making your walls appear even and clean. Plaster also serves as a base for other painting techniques, such as distempering or whitewashing. Exterior walls also require plastering. This can protect the building surface from damage caused by rain, wind and other environmental factors.

Plastering is done to protect the building from external hazards. Plastering is also done to hide the defects in masonry. Plastering walls with cement plaster is a common practice. This article will cover everything you need about cement plastering.

What is Cement Plaster ?

Cement plaster is a mixture of Portland cement, fine sand aggregates and water. There are three grades for Ordinary Portland Cement. OPC 43 is mixed in various proportions with sand to prepare cement plaster. The mix is known as cement sand plaster. PPC cement may also be substituted for OPC when plastering.

The cement plaster is a thin paste that is applied to the surface of a wall. The number of coats can vary according to the requirement. A single coat of wall plaster will achieve the desired results for the interior surface. Two coats of the plaster will give you a refined finish. The thickness of the plaster can be anywhere between 15 and 18 mm. Three coats of plaster may be required if the surface is uneven. The first coat in such situations is called the scratch coat or dash coat. The finish coat creates a smooth, even surface. Two coats of plaster are sufficient for the exterior. The thickness can range from 12 to 18 mm.

How to apply Cement Plaster?

Cement plastering requires professional skills. Skilled workers are able to meet your needs for a smoother surface finish on the walls. Workers without the necessary experience cannot achieve a smooth and elegant finish on walls. Interior Plastering in Auckland requires a variety of tools. The following list includes the tools you will need:

• Surveying equipment
• Steel Brush
• Mobile scaffolds
• Aluminum section
• Wood float
• Buckets
• Wheelbarrow
• Trowel
• Plumb Bob
• Spirit level
• Mixture machine

You must prepare the surface before you start to plaster. Follow these instructions:

Surface Wall Preparation

• Keep the mortar joints on the wall as rough as possible. This will provide a good bond to hold the plaster.
• Make sure to roughen the entire wall surface.
• Clean the wall thoroughly. It is important that no grease or oil remains on the wall surface. Cleaning can be performed with a wire brush.
• Before you begin plastering, cover any holes or cavities in the wall with appropriate material.
• Rake out the mortar joints to a depth around 12 mm if the surface wall has already been smoothed or if the wall is older. This will improve the bonding.
• Wash the wall thoroughly. The wall should be wet at least six hours before you apply cement plaster.

Plastering the ground

• You can use dots to get a uniform wall finish. A dot is a patch of 15 mm x 15 mm plaster with a 10 mm thickness.
• The dots are placed horizontally and vertically, at a distance of about 2 meters. The entire wall should be covered.
• Plumb bob can be used to check verticality by placing dots one above the other.
• Between the dots, plaster strips, or screeds as they are also called, form. These screeds can be used to maintain an even thickness in plasterwork.

How to apply base coat or under coat

• The thickness of the plaster on the first coat is 12 mm for brick masonry. Concrete masonry can vary between 9 and 15 mm.
• For first coat plaster, the ratio of cement to sand can range from 1:3 up to 1:6.
• The screeds leave spaces in the surface of the wall. Use a trowel to apply plaster between the screeds.
• To level the surface, you can use straight wooden edges and wooden floats.
• Let the first coat dry on the wall after leveling. Do not allow it to dry completely. Use a scratching instrument to roughen the surface to create a key for the next coat of plaster.

Finishing coat

• The thickness of a finishing coat can vary from 2 to 3 mm.
• The ratio of cement to sand for the final coat can range from 1:4 to 1:16.
• Before applying the final coat, it is important to dampen down the initial coat.
• You can achieve a smoother finish with a wooden float.
• Apply the top and bottom coats in one motion to avoid jointing.

Curing plastering works

• Water sprinklers should be used to dampen the wall for at least 7 days after the plastering is completed. This will ensure that the entire surface is adequately wet. Curing is required to achieve the desired strength and hardness.
• You can use gunny bags, or other materials to keep the exterior wall damp.
• If you do not follow the correct curing methods, it can cause cracks and unevenness. Make sure you follow the correct curing method.
• After 24 hours, the plastering job should be completed.
• The first coat should be applied seven days after the second.
• Keep each coat wet for at least five days.
• In colder climates, a longer curing time may be required to achieve maximum strength.
• The curing process can be initiated in hotter climates as soon as cement mortar begins to set. The weather conditions determine the type of curing method to be used.

Differences in Cement Plaster Thickness

The thickness of cement plaster is largely determined by the materials used and the characteristics of the surface to be covered. This chart shows the recommended thickness for plasterwork in regular home finishes.

The thickness of the finishing coat can vary depending on factors such as the condition and type of wall. It should be thick enough to support site conditions. The total thickness of two coats of plaster is not to exceed 20 mm as a standard. A three-coat thickness of plaster should also be less than 25 mm. In general, plaster thicknesses of 10mm are used for the ceiling and 15mm on interior walls. Plaster thicknesses of 20mm are usually used on exterior walls.

Different Cement and Sand Ratio

It is important to maintain the proper ratio of cement and sand when preparing plaster mixture. A plaster mix that contains too much sand is unusable and will peel off in a matter of years. A wall can crack if there is too much cement. Sand used in plasterwork must be free of impurities, clean, sharp and properly graded. This chart shows the standard cement to sand ratio for plasterwork.

The ratio of cement to sand in the final coat will depend on the texture and color desired for the wall surface. Mix the ingredients with a cement mixer after adjusting the proportions. To maintain the desired consistency, add water.

How to Mix Water for Desired Consistency

For making plaster, freshwater is best. Make sure the water is free of chlorides, organic impurities, such as silt, oil, alkalis and acids, and other salts. The plaster mix will be affected if you use water that contains these impurities.

For to achieve maximum strength, the amount of water used should be between 28% and 30% of the cement weight. An additional 4% of the weight of the aggregates is also required. The amount of water can vary depending on a number of factors.

• Condition and nature of aggregates
• Climate conditions and humidity levels in the area
• The mix is rich
• Composition of lime in mortar mix
• Additives to increase the workability

In the case of regular plastering, approximately 20% of the weight of aggregates and cement is water. The amount of water you need will depend on your exact circumstances. For small jobs, manual plastering is best. Cement plastering machines are good for larger projects.

Benefits of Cement Plaster

Here are some advantages to using cement plaster.

• The cement plaster coats walls very well and prevents moisture from circulating through them.
• Cement plaster is more efficient than lime plaster.
• Both the internal and external surfaces of a wall can be covered with cement plaster.
• To a certain extent, cement plaster can withstand chemical and vegetation attacks.
• The cement plaster can also resist fire damage
• Cement plaster is excellent for acoustic purposes

The Disadvantages Of Cement Plaster

Cement plaster has many advantages, but it also has some drawbacks. The disadvantages are:

• For a successful seal, pre-curing and after-curing is essential.
• Cement plaster is a flexible and low-tension material, which may cause cracks.
• The cement plaster can’t be applied to a smooth surface
• Plastering requires a lot of water, which can be a problem in areas without enough water sources
• It is a time-consuming task to apply cement plaster, and it can also increase the overall project cost.

Summary

Although plasterwork isn’t a necessity, it can certainly enhance the beauty of your home. Plasterwork is required for brick masonry. Plastering can enhance your home’s value and add aesthetics. It allows you to use a variety of colors and finishes on the walls. It can also protect your home from external environmental hazards. It is always a good idea to spend more money on cement plasterwork.