Have you ever seen a wall that’s been plastered but still looks rough? Or a wall that looks smooth at first, but then develops small cracks after a while?
One possible cause can stem from the very beginning: errors in the plastering or finishing process. It may seem trivial, but plastering and finishing play a crucial role in ensuring that walls are smooth and resistant to cracking.
It’s no surprise, then, that Milanians who work as construction workers understand the difference between plastering and rendering from the very beginning, before they start building a house.
The two have different functions but are interrelated, so errors in their execution can affect the final result.
So, what exactly is the difference between plastering and rendering? Which is more important? Let’s take a look at the full details below!
Why Are Plastering and Rendering Both Important for Walls?
Plaster serves as a layer that levels and covers the surface of masonry, lightweight brick, or concrete. Walls built with bricks typically have joints, gaps, and uneven surfaces.
Plastering makes the surface more uniform while also providing a better base for the next finishing step.
Meanwhile, skim coating serves to create a much smoother surface once the plastering is complete. The skim coat helps seal the pores and smooth out the rough texture of the plaster, making the wall better prepared for painting or other finishes.
So, the difference between plastering and skimming doesn’t mean that one of them can be omitted. Plastering shapes and levels the wall’s base, while skimming refines the surface. Both are part of the same series of wall-finishing steps.
What Are Plastering and Rendering?
Plastering is the process of coating a wall surface with a mixture of cement and sand to level it, cover brick joints, and create a stronger, more uniform base surface.
Plaster can be applied to brick walls, lightweight brick walls, or specific construction surfaces as required by the project.
Plaster is typically thicker than skim coat because it is used to correct unevenness in the wall surface. This is where the quality of the mortar, the condition of the surface, the application technique, and the drying process have a significant impact on the final result.
Meanwhile, skim coat is a thin, cement-based layer applied over plaster. Its primary purpose is to make the wall surface smoother, denser, and ready for a coat of paint or other finish. A skim coat is not intended to replace the function of plaster in leveling severely uneven walls.
Simply put, plastering can be considered a shaping and leveling layer, while finishing is a smoothing and refining layer.
See Also: AAC vs. CLC Lightweight Bricks: What’s the Difference, and Which One Is Best for Your Home?
The Difference Between Plastering and Rendering on House Walls
1. Function
The most obvious difference between plastering and rendering is their function. Plastering is used to level wall surfaces while also covering joints and irregularities in the brickwork. This layer serves as the base before the wall moves on to the finishing stage.
Skimming is primarily used to achieve a smoother surface. Once the plaster is sufficiently level, skimming is used to fill in pores and even out the texture, making the wall look smoother and better prepared for painting.
2. Materials Used
Plastering typically involves a mixture of cement, sand, and water. The type and composition of the materials must be adjusted to suit the surface conditions and the requirements of the job so that the mortar has good adhesion and strength.
Skimming typically uses cement-based materials mixed with water to produce a smoother mortar. Because the layer is thin, the quality of the materials and the consistency of the mortar greatly affect the surface finish.
3. Thickness
Plaster is applied thicker because it must help level the wall surface. In field work, the thickness may vary depending on the condition of the wall and the applicable work standards.
The finish coat is much thinner. Its sole purpose is to smooth out the surface of the plaster; it is not intended to correct walls that are uneven or have significant variations in thickness.
4. Work Sequence
The sequence of work is also a key difference between plastering and rendering. Plastering is done first, after the wall has been built and the surface has been prepared.
Once the plaster has dried sufficiently and is ready for the next step, the finish coat is applied. So, generally speaking, the sequence is as follows: wall framing → plastering → skim coat → finishing or painting.
5. Texture
Plastered surfaces usually still have a relatively rough texture. This is to be expected, since the plaster serves as a base layer to ensure the wall is level.
On the other hand, plaster produces a smoother and denser texture. Since it forms the outermost layer before the final finish, the quality of the plaster largely determines whether the wall’s surface looks smooth or still has pores and unevenness.
6. Final Results
Plastering creates a flat, sturdy wall surface that serves as a base for finishing. However, the surface may not be smooth enough to paint directly if a neat finish is desired.
Plastering produces a smoother and more uniform finish. Therefore, the quality of the plastering work will be particularly evident when light hits the walls or after they’ve been painted.
What Will Happen If Walls Are Directly Plastered Without a Base Coat
Applying mortar directly to the brickwork is not the right way to replace plaster.
The surface of the bricks has joints, pores, and irregularities that cause the plaster to have to work too hard to cover those differences.
As a result, the plaster layer may have an uneven thickness. Some areas may be too thick, while others are too thin.
These conditions can increase the risk of cracking, peeling, or result in a wall surface that remains uneven.
In addition, skim coat is not the primary material for correcting significant unevenness on walls. Therefore, Milanians should follow the plastering steps first, then apply the skim coat, so that each layer functions as intended.
See Also: Learn About the 8 Causes of Cracks in Wall Plaster and How to Fix Them
Mistakes in Plastering and Finishing That Can Cause Walls to Deteriorate Quickly
1. The Wall Surfaces Are Still Dirty and Greasy
Before plastering or rendering, the surface must be free of dust, dirt, oil, and other materials that could interfere with adhesion. If the surface is still dirty, the mortar will not adhere properly, making the coating more likely to come loose or peel off.
2. The Walls Are Still Too Rough; They Haven’t Been Smoothed Yet
The plaster should form a sufficiently level base before moving on to the finishing stage. If the surface is still uneven or has large bumps and depressions, it will be difficult to achieve a consistent finish.
Don’t try to use the finish coat to correct unevenness that should have been addressed during the plastering stage. Each layer serves its own purpose.
3. The Composition of the Mixture Is Incorrect
An improper mix of materials can affect the strength, adhesion, and drying process, as well as increase the risk of cracks in plaster and render.
A mixture with too much water, too little binder, or one that isn’t mixed evenly can result in a suboptimal coating.
Therefore, the mix composition must be prepared accurately and consistently according to the requirements of the job. To help reduce the risk of cracking in plaster or stucco, Milanians can use cement-based mixes from Milan Cement Additive.
Milan Cement Additive is formulated to help improve the quality of cement mixes and their bonding strength, while reducing the risk of cracking in plaster and render.
4. Improper Application; Thickness Ignored
Uneven application can result in some areas having a coat that is too thick and others that are too thin. These differences in thickness can lead to uneven drying and increase the likelihood of cracking.
The application technique must be adapted to the surface conditions. Make sure the plaster is properly leveled before proceeding to the finishing process.
5. Not Allowing Time for Drying
Plastering and finishing require time for the layers to reach the proper condition before proceeding to the next stage. If the finishing is done too soon, the underlying layers may still undergo changes during the drying process.
These conditions can lead to problems such as hairline cracks, an uneven surface, or a suboptimal finish. Therefore, don’t just focus on finishing the job quickly; allow sufficient time for each step.
Why Are Milan Cement Additives Important in the Composition of Plaster and Rendering Mixes?
In plastering and rendering work, the quality of the cement mixture greatly affects the final result. Milan Cement Additive Designed as a cement additive that helps improve the quality of the mix and reduce the risk of cracking in plaster and render.
The use of Milan Cement Additive can help improve adhesion between the cement and the substrate, resulting in a stronger and neater finish.
Milan Cement Additive can be used in brick walls, concrete, and cement plaster applications, for both interior and exterior areas. This product is also designed for residential projects, commercial buildings, renovations, and new construction.
Some of the advantages of Milan Cement Additive include:
- Helps retain water in the cement mix
- Reducing waste in the mortar mix
- Helps reduce cracking caused by differences in the drying process
- Helps prevent the plaster from drying too quickly, making it easier to smooth out
- Helps improve the adhesive strength of plaster
- Resistant to lime and weather
- Suitable for plastering and rendering
How to Use Milan Cement Additive as a Cement Admixture in Plastering and Rendering
1. Prepare 1 bag of cement weighing 40 kg as the main ingredient for the mixture.
2. For the base plaster, mix 1 bag of cement with 1–2 packets of Milan Cement Additive, then mix in fine sand in a 1:3–4 ratio until thoroughly blended.
3. For a smooth plaster or finish coat, mix 1 bag of cement with 1 package of Milan Cement Additive, then add enough water to form a paste that is ready to use for smoothing the wall surface.
4. To lay bricks, mix 1 bag of cement with 1–2 packs of Milan Cement Additive, then stir in river sand in a 1:3–5 ratio until evenly mixed.
5. Gradually add water to the mixture as needed until it reaches the right paste-like consistency and is easy to apply to the wall surface.
So, Which Is More Important When Building a House Wall: Plastering or Rendering?
If you had to choose, it’s actually not accurate to say that plastering is more important than rendering—or vice versa. Both are important because they serve different functions and complement each other.
The plaster determines the quality of the wall's base. If the plaster is uneven, too thick, has poor adhesion, or cracks easily, it will be difficult to achieve a smooth finish.
Conversely, even well-applied plaster still requires skimming if the goal is a smooth wall surface that is ready for finishing.
So, what matters most in determining the quality of a wall isn’t just choosing one option, but ensuring that the entire process is carried out correctly.
Every step—from surface preparation, mortar composition, and plaster application to drying and the application of the finish coat—must be carefully considered.
FAQ (Frequently Asked Questions)
What Is the Correct Order for Plastering and Finishing?
The process begins with preparing the wall surfaces, followed by plastering to level the surfaces. Once the plaster has reached the appropriate condition, the next step is skim coating to smooth the surfaces before moving on to the finishing or painting process.
What Is the Ideal Thickness for Plaster and Finishing Coat?
The thickness is not always the same, as it depends on the condition of the wall and construction standards. Generally, the thickness of plaster ranges from 10 to 20 mm, while that of skim coat ranges from 1 to 3 mm. However, the application thickness cannot be standardized; it must be adjusted according to the specific requirements of the surface.
Why Do Plaster and Rendering Crack or Peel?
The causes may include a dirty surface, an improper mix composition, uneven thickness, poor adhesion, incorrect application techniques, or an inappropriate drying process. Selecting the right cement mix materials can also help reduce these risks.
How Much Does Plastering and Finishing Cost per Square Meter?
The cost of plastering and rendering per square meter varies depending on material prices, wall type, thickness of the application, surface condition, project location, and labor costs. Therefore, calculations should be based on material requirements and local labor rates at the project site.
Which Is More Important in Determining the Quality of a Wall Finish?
Both are equally important. Plastering determines the levelness and quality of the wall’s base, while skim coating determines the smoothness of the surface. A good wall finish requires both plastering and skim coating to be done correctly—not just one or the other.
Want to Reduce the Risk of Cracks in Wall Plaster and Rendering? Use Milan Cement Additive!
It’s important to understand the difference between plastering and skimming on the walls of a house before the project begins. However, to prevent the plaster and skim coat from cracking shortly after application, make sure the mixture has the right composition and is of high quality.
Therefore, Milanians can use Milan Cement Additive as an additive in cement mixtures to help improve adhesion and the quality of plaster and render.
So, don’t wait until the plaster and render start to crack—prevent it right from the start with Milan Cement Additive!
Interested in using it? Milanians can consult with Milan’s team of experts about their project needs by clicking the banner below!
