What should be the thickness of the plaster on the walls

Getting the thickness just right is one of the most crucial factors when plastering walls. If it’s too thick, you could experience problems with cracking or even incur extra costs. If the plaster is too thin, it might not give you the desired finish or durability. Getting that balance right is essential for a good plastering job.

Depending on the type of wall, the purpose of the space, and the type of plaster being used, there are differences in the ideal thickness of plaster. For instance, a different strategy might be needed for internal walls than for external walls, where weather resistance comes into play. Recognizing these variations contributes to the plaster’s long-term performance.

You can choose the ideal plaster thickness to achieve a smooth, durable finish by paying attention to the particular requirements of your project as well as some general recommendations. This post will examine the variables that affect plaster thickness and provide helpful advice to ensure that it is perfect.

Layer thickness for different surfaces

Plaster layers can differ based on the kind of base:

1. Brick. This material is characterized by the presence of a relief pattern, which increases adhesion to the plaster. The minimum layer of plaster is 5 mm, it should not be applied less, since the solution is not enough to hide all defects in the brick surface. The maximum thickness of plaster without installing a reinforcing mesh is 2.5 cm, with the installation of this element – 5 cm.
2. Concrete walls. The porous structure of such coatings ensures good adhesion to all types of plaster. In addition, such surfaces are mostly smooth, so you can apply a solution with a thickness of 2 mm. The maximum layer of plaster without using a mesh is 2 cm, with a reinforcing mesh – 7 cm.
3. Cellular concrete. Walls made of gas or foam blocks rarely need leveling, since they have a smooth surface. Most often, they are plastered only for decorative purposes, so the layer thickness varies from 2 to 15 mm.
4. Wooden covering. Plaster is rarely applied to a wall of this type, since the solution does not hold well. Application of mixtures to a wooden wall begins with the installation of a reinforcing mesh. It can be metal, plastic or wooden. Metal and wooden products are attached with nails or screws, and plastic ones with special glue. The thickness of the plaster layer on the mesh is not regulated, since it is only needed to hide it. The recommended thickness of the solution is 2 cm.
5. Drywall. This material is used to level the walls, so it only requires decoration. If it was decided to use plaster, the material must be of high quality. Usually 2 mm is enough for decoration, the maximum permissible layer is 10 mm. If for some reason it is planned to apply a thicker layer, then a plastic reinforcing mesh is first installed.
6. Insulation. Contrary to the opinion of some craftsmen, it is not only possible, but also necessary to plaster foam, mineral wool and other thermal insulation materials. The work begins with the installation of a reinforcing mesh, then a little solution is applied to mask the mesh, and at the end the main one, the thickness of which is 1-2 cm.

Note: The manufacturers indicate which layer of plaster can be applied on the packaging. Read the instructions through carefully before starting any work.

Thickness of different layers of plaster

We refer to the initial layer as a splash. It is applied to improve the material’s primary adhesion to the coating. Its application involves a liquid solution. The material is just thrown onto the wall without being leveled, creating an uneven coating that will help the plaster’s main layer lie more evenly after drying. For brick and different types of concrete, the maximum layer that can be applied is 5 mm; for wood, it is 8 mm.

A thick layer of plaster is applied to the surface once the splash has dried. It’s the primary one and is referred to as a primer. Cement mortars should be 0.5–5 cm thick, and gypsum plasters or lime compositions should be 0.7–3 cm thick.

Finally, a cover is put on. This layer of plaster is applied after the majority of the mixture has dried; it should only be very thin, perhaps 2 mm thick. Five millimeters is the maximum allowed layer.

You should know this! For single-layer cement-based plaster, a recommended layer thickness is 2 cm; for gypsum-based plaster, it is 1.5 cm.

Possible deviations

If we are talking about simple plaster, then in the vertical plane the deviation may not exceed 15 mm for the entire wall and not more than 3 mm per meter. For high-quality coatings, the maximum permissible deviation is 5 mm for the entire wall or 1 mm per 1 meter. In addition, the number of deviations is also limited. For every 4 square meters of surface, there may be no more than 3 defects, provided that ordinary plaster is used. For high-quality surfaces, no more than 2 deviations. The depth of unevenness should not exceed 5 mm for simple coatings and 2 mm for high-quality ones. Deviations in the horizontal plane are regulated in the same way as in the vertical.

Exception to the rules

There are instances where the walls’ curvature is so severe that mortar that is more than 5 cm in diameter needs to be used. An additional 2 cm of layer requires the use of a reinforcing mesh. Although plaster is not the most expensive building material, it is necessary in large quantities, so in certain situations it is preferable to forgo mixtures in favor of gypsum plasterboards. Furthermore, since these materials are fairly heavy, you must confirm that the wall you are processing is trustworthy before beginning any work.

Finding the ideal plaster thickness is essential to having a smooth, long-lasting wall finish. A robust and long-lasting finish can be achieved by adhering to the recommended plaster thickness guidelines, whether you’re working on an exterior or interior surface.

A thickness of approximately 10 to 15 millimeters is ideal for the majority of interior walls. This range is thin enough to dry properly, yet it offers enough coverage to blur any imperfections. For increased protection and durability, a thicker layer—usually between 15 and 25 millimeters—is required when working on external walls or surfaces exposed to the elements.

But the precise thickness can change based on things like the kind of wall, the state of the surface, and the plastering technique you’re employing. Before beginning your project, evaluate these factors to make sure you’re applying the right amount.

In conclusion, knowing and using the proper plaster thickness for your walls will improve the overall outcome and provide you with a finish that is durable, smooth, and aesthetically beautiful.

For durability and a smooth finish, the proper thickness of plaster must be applied to the walls. The ideal plaster thickness typically varies depending on the type of plaster being used and the state of the wall, but for most interior walls, a general guideline is between 10 and 20 mm. By doing this, you can be sure that the plaster will adhere correctly, offer good insulation, cover any imperfections, and create a stable, even surface that is ready for additional finishing.

Video on the topic

Is it worth doing THIS? Plastering walls in a thick layer. What to do? Repair mistakes. Apartment renovation.

What is the catch in applying a THICK layer of plaster?

Plastering in a thick layer

Minimum and maximum layer of plaster

Cement Sand Plaster. From A to Z. Master class. Manual application. Along beacons.

Aligning the wall with base putty / Correcting poorly applied plaster