Because it strengthens the walls and gives them a flawless finish, plastering the inside and outside of your home is a crucial chore. Make your walls look smooth, even, and clean by applying a plaster coat over uneven surfaces. Painting, distempering, whitewashing, or colour-washing can all be successfully executed on a plastered surface. It shields the walls from precipitation and other elements that might cause structural harm.
Cement, lime, gypsum, water, and fine aggregates (sand) are some building ingredients that go into the polymeric material or mortar utilised. Cement plaster is the material of choice for most home plastering jobs. Here, you can discover some basic facts about cement plaster.
What Is Cement Plaster?
A combination of water, fine particles, and Portland cement forms cement plaster. This plaster is also known as cement-sand plaster since it typically contains varying mixes of fine aggregate (sand) and cement (OPC 43 or OPC 53 grade). When plastering, PPC cement is better than OPC-grade cement. The reason is PPC cement has several benefits that OPC cement does not.
Depending on the need, various plaster applications may be put in. Typically, a single layer of plaster is enough to attain the desired finish for interior walls. It is necessary to apply two coats of plaster if the thickness exceeds 15 mm or if a finer finish is desired. If the surface that needs to be plastered is extremely uneven, it may be necessary to apply three coats of plaster, with the first layer as a scratch or dash coat, to achieve a smooth finish. Next, apply the base and final coats. The plaster should be 12 to 18 mm thick and applied to the exterior wall in two coats.
What Makes Cement Plaster Beneficial
You might be astonished to learn from watching some home repair shows that some older homes have severe brick and stonework problems, and the danger of collapse appears immediately once the plaster is removed.
Where these walls have managed to withstand the test of time and remain upright in the face of a strong wind, plaster has unquestionably contributed to reinforcing the walls and columns, protecting the structure's weak points, and extending its useful life.
In addition to a degree of fireproofing, soundproofing, thermal insulation, and protection from water intrusion, plastering also offers some protection from the elements. (You can get spray fireproofing products made of plasters that contain cement.)
It conceals weak or porous materials, poor craftsmanship, uneven surfaces, or other flaws in the construction with a long-lasting, smooth, and aesthetically pleasing ornamental finish. Plastering over bumps and divots prepares a smooth surface for priming and painting.
How Much Water Is Necessary for Plastering?
The moisture content of the cement, sand, and ambient conditions dictate the water added to the mixture. The percentage of water in the combined dry ingredients (cement and sand) is 20%.
Cement Plastering Tools
- Tools: bucket, utility knife, hammer, handsaw, trowel, paintbrush, and bucket
Adding Water To The Mix
The ideal water for mortar is potable. Mortar can be compromised if it contains chlorides or organic contaminants such as acids, silt, oils, alkalis, or salts.
Plastering using a 1:3 ratio requires around 70% of the cement's weight in water. However, this percentage might vary based on variables like:
- Plastering conditions (including humidity and temperature), fine aggregate conditions,
- No matter if the ratio is more or less than 1:3;
- What proportion of lime is in the mortar?
- Any additives that make the combination easier to work with.
The typical amount of water in a plaster container for residential use is between fifteen and eighteen per cent by weight.
Plaster of Cement Must Have Adequate Thickness
The plaster's thickness is determined by the plaster's composition and the surface that needs to be plastered.
- To get a smooth finish on concrete walls, keeping the plaster thickness at least 10 mm is recommended.
- A 12- or 18-mm thick plaster works well on uneven brick masonry surfaces.
- A 20 mm thickness is required for any other extremely uneven surface.
To ensure satisfactory hardening under site conditions, the finishing layer should have a minimum thickness that provides enough material body. Ideally, a two-coat plaster would be at most 20 mm. The recommended minimum thickness for a three-coat plaster is 25 mm. The standard plaster thickness for outside walls is 20 mm; for interior walls, it is 15 mm; and for ceilings, it is 10 mm.
Procedure for Plastering Work
Steps to Get the Surface Ready for Plastering
- If you want to give an excellent bond to hold plaster, all of the wall's mortar joints must be very tight.
- Use a string brush to scrub or clean the wall's joints and surfaces. Before plastering, the floor must be free of any oil, grease, or efflorescence traces.
- Fill any holes or voids in the floor and any loose or subpar materials with the appropriate authorised material as soon as possible.
- For a smooth floor or ancient wall that needs plastering, rake the mortar joint to 12–20 mm to adhere it to the floor.
- Before applying cement plaster, wash the mortar joints and finish the wall that will be plastered. Keep it wet for at least 6 hours.
- To get a level wall surface, knock off any projection at the floor over 12 mm. Plaster use will decrease.
Using the Base Coat or Undercoat Application
Preliminary Groundwork
- Plastering must be a consistent thickness throughout the wall and floor, so the dots on the wall must be spaced 2 metres apart in both the horizontal and vertical directions. The dimensions of the plaster dot pattern are 15 mm x 15 mm with a thickness of about 10 mm.
- The 2m x 2m patches are tested for verticality, and screeds are made according to the appropriate thickness with the help of a Plumb bob.
To ensure proper bonding between the floors, a cement slurry coat is sometimes applied to the floor of the walls.
Application Method for Base Coat and First Coat
- For the first coat of plaster, the cement-to-sand ratio might range from one to six.
- Plaster thickness ranges from nine to fifteen millimetres for concrete and ten millimetres for brick masonry.
- Patches made on the floor of the wall need to be plastered with the first coat. Trowels are used for this purpose. Make the floor level using flat timber floats and timber at the edges.
- You can't wait for the first coat to dry before setting it. To prepare it for the second coat of plaster, use a scratching tool to make it rough.
Applying Finishing Coat
- Be sure to keep the first coat wet before applying the second coat.
- A finishing coat is applied as a last step in the plastering process. A two-coat or finishing coat of cement and mortar at a ratio of one-fourth to one-sixth may have a thickness of two to three millimetres.
- Coatings must be applied in a single operation, working their way down from the top to the bottom to prevent joining marks.
Curing Of Plastering
- After each coat, the plaster is sprinkled with water so that it can be kept moist for at least seven days to increase its electrical charge and hardness.
- Cracks or efflorescence can also be caused by improper curing in plaster paintings. You can use gunny sacks to keep the floor moist to achieve the proper curing.
FAQs About Plastering
Cement plaster typically sets within a few hours but requires several days to cure fully. The drying time may vary depending on environmental conditions such as temperature and humidity.
Yes, cement plaster can be reinforced with fibres or additives to improve strength, flexibility, or resistance to cracking, depending on the project's requirements.
Yes, cement plaster is compatible with many substrates, including concrete, masonry, brick, and metal, making it suitable for various construction and renovation projects.
Yes, cement plaster can be painted with suitable exterior or interior paints once fully cured. It can also be textured or finished using decorative techniques to achieve desired aesthetics.
Hire experienced plasterers who follow proper preparation and application techniques to ensure quality. Regular maintenance and timely repairs can also help preserve the integrity and appearance of cement plaster surfaces.
Concrete/Cement Plaster Finishes
There are several different types of coatings for concrete/cement plaster:
Smooth Cast
A wooden float, composed of fine sand and cement, is used to apply mortar. Exterior walls typically have this finish. The extremely smooth results produced by a steel float are susceptible to cracking when exposed to the weather, so it ought to be avoided.
Roughcast
The ingredients in this plaster include sand, cement, and gravelly sand or coarse aggregate. A wooden float is used to level the surface after a large quantity is "thrown" onto it with a trowel.
Sand-Faced
This plaster is a waterproofing coating put over masonry using a cement-sand mix. While the second coat is still wet, use a sponge to smooth the surface texture by acting like a sand grain. Cracks will be less noticeable after this.
Scrapped
After the last layer has dried for a few hours, it is roughened up by dragging a toothed blade or comparable tool across the surface.
Textured
To achieve various plaster finishes, certain tools are needed.
Curing Of The Plaster
Curing cement plaster is essential because it strengthens the wall and decreases surface cracking. Cement plaster needs at least 24 hours to cure after application. For the first seven days after plastering, the surface should remain damp. In addition, wait seven days before applying a second layer. For at least five days, each coat must be kept wet continually. The last step is to apply the next layer after thoroughly moistening the base coat.
Lengthier curing times are required when the temperature is chilly. It would help if you began curing the cement mortar when it shows signs of setting in hot or warm weather with less humidity or wind.
Strategies and Machines for Plastering
Applying plaster and cement is one of the most important and time-consuming steps in building anything. It is crucial to the building's structural integrity and serves as the building's inspiration. It can devour time and money because plaster software stages from exterior walls, interior walls, ceilings, and almost every other area to impart an easily finished floor. Currently, most of the world is still using the time-consuming and labour-intensive technique of hand-plastered walls, which involves masons and labourers.
Reasons To Use A Plastering Tool
- Compared to historical or traditional plastering techniques, modern plastering equipment can achieve the following goals.
- Reduced labour costs directly result from this plaster machine's ability to replace human artists. (This factor may be best considered in a handful of exceptional circumstances since hard work employment is critical for every nation.) Regardless, operating machines require professional-level effort.
- Preventing mortar waste lowers construction costs.
- In conjunction with rapid plaster covering, more precise plastering is possible.
- Plastering can be less expensive per square metre for large-scale creative projects.
Conclusion
Cement plaster is a popular choice for home plastering due to its strength, flawless finish, and protection from structural damage. It is made from a combination of water, fine particles, and Portland cement, with PPC cement being better than OPC-grade cement due to its benefits. Plastering can be applied over uneven surfaces, with a single layer typically sufficing for interior walls. If the surface is extremely uneven, three coats may be needed, starting with the first layer as a scratch or dash coat. The plaster should be 12 to 18mm thick and applied to the exterior wall in two coats.
Cement plaster is beneficial for reinforcing walls and columns, protecting weak points, and extending their useful life. It also provides fireproofing, soundproofing, thermal insulation, and protection from water intrusion. It conceals weak materials, poor craftsmanship, uneven surfaces, or other flaws in construction with a long-lasting, smooth, and aesthetically pleasing finish.
The water required for plastering depends on the moisture content of the cement, sand, and ambient conditions. A 1:3 ratio requires around 70% of the cement's weight in water, with a typical amount of 15-18% by weight for residential use. The plaster must have adequate thickness, with a minimum thickness of 20mm for concrete walls, 20mm for interior walls, and 10mm for ceilings.
Plastering is a crucial and time-consuming process in building, requiring consistent thickness throughout the wall and floor. The plaster dot pattern is 15 mm x 15 mm with a thickness of about 10 mm. The first coat of plaster should have a cement-to-sand ratio of one to six and a thickness of nine to fifteen millimetres for concrete and ten millimetres for brick masonry. The first coat should be applied with trowels, leveling the floor using flat timber floats and timber at the edges. The second coat should be prepared by using a scratching tool to make it rough. A finishing coat of cement and mortar at a ratio of one-fourth to one-sixth may have a thickness of two to three millimetres. Coatings must be applied in a single operation, working their way down from the top to the bottom to prevent joining marks. After each coat, the plaster should be kept moist for at least seven days to increase its electrical charge and hardness. There are several types of plaster finishes, including smooth cast, roughcast, sand-faced, scraped, and textured. Cement plaster needs at least 24 hours to cure, and longer curing times are required when the temperature is chilly. Modern plastering equipment can reduce labor costs, prevent mortar waste, provide more precise plastering, and be less expensive per square metre for large-scale creative projects.
Content Summary
- Plastering both inside and outside your home is crucial for strengthening walls and achieving a flawless finish.
- A plaster coat over uneven surfaces can make walls look smooth, even, and clean.
- Cement plastering offers protection from precipitation and structural harm.
- Cement, lime, gypsum, water, and fine aggregates are key ingredients in polymeric mortar.
- Cement plaster is the preferred material for most home plastering jobs.
- PPC cement is preferred over OPC-grade cement for plastering due to its benefits.
- Different plaster applications may be necessary depending on the desired finish and surface conditions.
- Applying two coats of plaster is necessary for thicknesses exceeding 15 mm or for a finer finish.
- Plastering can reinforce walls, protect weak points, and extend a structure's useful life.
- Plastering offers fireproofing, soundproofing, thermal insulation, and protection from water intrusion.
- Plastering conceals flaws and provides an aesthetically pleasing finish.
- The water added to the plaster mix depends on cement, sand, and ambient conditions.
- Essential tools for plastering include a bucket, utility knife, trowel, and paintbrush.
- Potable water is ideal for mortar to avoid compromising its quality.
- Water percentage in plastering varies based on conditions and additives.
- Plaster thickness depends on the surface being plastered and desired finish.
- The standard thickness for exterior walls is 20 mm, while for interior walls and ceilings, it's 15 mm and 10 mm, respectively.
- Proper surface preparation is crucial for effective plastering.
- Plastering must be consistent in thickness throughout the surface.
- Cement slurry coat is sometimes applied for proper bonding between surfaces.
- The first coat of plaster requires a specific cement-to-sand ratio.
- Plaster thickness varies for concrete and brick masonry surfaces.
- Proper curing is essential for plaster strength and crack prevention.
- Different plaster finishes include smooth cast, roughcast, sand-faced, scrapped, and textured.
- Curing cement plaster requires at least 24 hours after application.
- Longer curing times are necessary in chilly temperatures.
- Modern plastering tools reduce labour costs and mortar waste.
- Machines enable more precise and rapid plaster covering.
- Plastering can be less expensive per square metre for large-scale projects.
- Hand-plastered walls are labour-intensive but still widely used.
- Cement plaster is essential for a durable and aesthetically pleasing finish.
- Proper water content is crucial for the quality of the plaster mix.
- Plaster thickness varies depending on the surface being plastered.
- Surface preparation is essential for effective plaster adhesion.
- Curing plaster properly enhances its strength and durability.
- Different plaster finishes offer various aesthetic options.
- Modern plastering tools offer efficiency and cost-effectiveness.
- Machines enable faster and more precise plaster application.
- Labour costs can be reduced with the use of plastering tools and machines.
- Proper curing is critical for the longevity of cement plaster.
- Cement plaster provides protection and reinforcement for walls.
- Plaster thickness should be consistent for a uniform finish.
- Surface cleanliness is essential before plaster application.
- Cement slurry helps improve bonding between surfaces.
- The first coat of plaster requires a specific ratio of cement to sand.
- Plaster thickness varies based on the type of surface being plastered.
- Proper curing prevents cracks and ensures plaster durability.
- Various plaster finishes offer different aesthetic appeals.
- Modern plastering tools and machines offer efficiency and precision.
- Proper water management is crucial for the quality of the plaster mix.
