What should be the thickness of the plaster of the walls

Plastering walls requires careful consideration of thickness. If the plaster is too thin, it could crack or be unable to conceal flaws; if it is too thick, it might result in extra expenses and possible problems like sagging. A smooth, long-lasting finish that not only looks good but also endures over time is ensured by the proper balance.

Depending on the type of plaster used, the state of the wall, and the intended use of the space, different surfaces and walls require different plaster thicknesses. In the future, knowing how to calculate the right thickness can save you money, time, and headaches.

This post will walk you through the most important factors to take into account when choosing the proper plaster thickness for your walls, enabling you to complete any project—new construction or renovation—with a polished finish.

Type of Surface	Recommended Plaster Thickness
Brick Walls	15-20 mm
Concrete Walls	10-15 mm
Uneven Walls	20-30 mm
Interior Walls	10-15 mm
Exterior Walls	20-25 mm

For a wall plaster finish to be smooth, long-lasting, and aesthetically pleasing, it must be thick enough. Based on the kind of wall surface, the plaster’s intended use, and the space’s specifications, it should be carefully chosen. For most interior walls, a thickness of 10 to 15 mm is adequate to provide adequate coverage to smooth out imperfections while preserving the plaster’s strength and integrity. It’s crucial to get this range exactly right because going above or below it can cause problems like poor adhesion or cracking.

Depending on the placement

The thickness of the plaster layer is also impacted by the stark differences in the working conditions of the plaster coating indoors and outdoors.

Which of the following coating properties are impacted by the laid layer’s size:

• strength of the coating;
• strength of the base;
• efficiency of leveling;
• financial and labor costs.

Depending on the quantity of layers and, therefore, the finish quality, the maximum thickness of the wall plaster can be expressed as follows:

A) 1.2 cm – basic (total splash and primer thickness);

B) An enhanced 1.5 centimeter (total of cover, soil, and spray layers);

C) 2.0 cm – superior quality (cover layer + 2 primer layers + splash).

The maximum value is chosen to lessen the possibility of cracks, drying plaster coating shrinkage, and freshly laid mortar sliding.

Visit our website to learn more about plaster flaws and the causes of its cracking in the materials.

Indoor plastering

The room’s design elements may have an impact on the plaster thickness on interior walls. For instance, the thickness of the coating is increased to conceal the location of electrical wiring if it is installed on the surface of the walls. Here, it is imperative to guarantee a minimum clearance above the wiring itself.

Higher standards are typically placed on the quality of the plaster finish in interior spaces. This is relevant to the surface geometry. Leveling is done if the walls collapse or if the angles between them are greater than or equal to ninety degrees. This may involve applying a layer that is larger than eight centimeters.

For practical reasons, a thicker layer might be required for dense reinforced concrete walls. For example, strong, dense concrete walls need to be drilled in order to install fasteners on which paintings are hung.

It is particularly crucial to guarantee the vapor permeability of the interior and exterior finishes for walls composed of cellular concrete. Such walls require constant removal of moisture. Consequently, adhere to this rule: the internal plaster coating needs to be twice as thick as the external one in order to avoid using complicated computations.

Thus, the internal plaster should not be any thinner than 20 mm if the external layer’s minimum allowable thickness is 10 mm. By using this technique, the room’s condensation won’t reach the wall’s base. In this instance, using a silicone or silicate mixture for facades would be the right decision.

Facade plaster

When it comes to facades, the most important factor is the coating’s strength because the base is vulnerable to significant mechanical impact due to the building’s exposure to weather, hail, strong winds, and rain. Furthermore, the protective role takes precedence over the ornamental one. This determines the makeup of the mixture that will be used on the exterior of the home. As a result, cement compositions are more frequently utilized in facade work, resulting in a minimum 10 mm layer of simple plaster.

Ensuring the integrity of the plaster coating during operation is another reason for the standardization of the minimum. A plaster layer that is too thin is not as strong. The finish will start to peel off and crack with just a slight mechanical load.

Insulation is frequently placed beneath the plaster layer when plastering a facade. In this case, the plaster shell needs to be extremely durable, solid, and trouble-free during use. Retaining the thickness and providing reinforcement help achieve this.

Plaster thickness depending on the type of mixture

Let’s talk about the appropriate plaster thickness to use with various compositions. Cement and gypsum are the most widely used. For rooms, lime compositions are also frequently utilized, along with clay finishing. Every component creates a coating, the thickness of which is determined by the thickness of the plaster layer. When the solution solidifies, this property can become extremely evident. If the coating is thinner than what is allowed, it will rip and dry, causing the plaster to crack. The filler fractions’ size also influences the minimum.

Gypsum or gypsum-sand mortar can be used to finish the space. The dry gypsum mixtures that the manufacturers have developed can be applied up to 50 mm thick (Volma-layer – up to 60 mm thick), per their recommendations. Although manufacturers specify a minimum thickness of 5 mm, artisans typically apply the gypsum mixture in a 3 mm layer. The minimum when applied by machine is 8 mm. SNiP states that a single-layer gypsum coating can be up to 1.5 cm thick.

The standard minimum for a cement mixture is 1 cm, and the maximum is 2 cm for a single layer. Plastering requires a splash layer up to 0.5 cm and a separate primer layer measuring at least 5 mm. There is a minimum of 10 mm of coating thickness overall.

Although lime mixtures are more frequently used in dry rooms, they can be used for outdoor finishing (with the addition of cement). Up to 5 mm of splash and up to 7 mm of primer are present. The thickness of the "buffer" should be at least 4 mm if the lime composition serves as an intermediary buffer layer between the cement and gypsum compositions.

A great plastic material is clay. It is most frequently applied to wooden surfaces, onto which plaster is applied after shingles are nailed. 10 mm is the minimum thickness of clay mixture over the shingles. Clay that is thinner in coating will just break off. Cement is added to the (mm)-10-35 clay-sand cement-free mortar, which has a thickness of 15-35.

Thickness for different bases

It is important to consider the type of wall material when finishing. Assuming that the walls are equally level, the plaster thickness for walls composed of wood, OSB, or concrete, for instance, will vary.

Brick

The size of the plastering mixture’s cross-section depends on the relief of the brick surface. If less than 5 mm is applied, poor distribution and subpar compositional work are not guaranteed; instead, the layer becomes ribbed with varying thickness. The best sizes are 2.0–2.5 cm, and the largest are 5.0 cm.

Concrete base

Panel houses have smooth concrete walls with a limited number of large pores. Plastering is done primarily for monolithic joints, heat and sound insulation, rather than for leveling. Here, a 2 mm layer can be used if there are no differences. The upper limit (with mesh reinforcement) in the event of wall rotation, unevenness, or collapse is 70 mm.

Aerated concrete blocks

Because the material is not as durable as brick or concrete, the cellular base may eventually become unable to bear the excessive weight of the plaster coating. The wall can be made even by using a plane to properly prepare it before plastering. Plastering aerated concrete blocks with a minimum of 2 mm is feasible in this situation. A layer that is between 0.8 and 1.5 cm thick can be applied to rectify any uneven walls. Anything above these markers is prone to breaking and toppling off. Aerated concrete blocks can occasionally have their surface destroyed.

Wooden surfaces

A plaster that is fairly intricate. Wood often dries out and becomes wet from too much moisture – "play". Not all plaster compositions can achieve consistent adhesion under these circumstances. A mesh or lath is fastened to the wall prior to plastering the wood to guarantee a solid connection with the base. The slats or mesh are covered with the first layer of plaster, followed by a second layer that is 15-20 mm thick.

Drywall

At first, the drywall sheets have a smooth surface. Plaster is used to fill in dents and joints caused by screw installation. Plastering drywall is used for irregularities up to 1.5 cm in length. As a result, the maximum plaster layer thickness for drywall bases is 1.5 cm, while the minimum plaster layer thickness is 1.5 mm.

Insulation materials

Penoplex and other wall-mounted insulation materials require additional mechanical protection because they are not very resistant to impacts or abrasions, especially polystyrene foam. These kinds of loads are particularly heavy in the basement. Thus, for strength, the plaster finishing over the insulation needs to be reinforced. The reinforcing mesh is first coated (1.5 cm) to create a monolith, and then a second layer (1.0–2.0 cm) is applied for protection and alignment.

Thickness of decorative plaster

Decorative compositions, which are intended to adorn facades and interiors, also have maximums and minimums.

Current finishes for decorative mixtures fall into two categories:

The thinnest plaster layer is a Venetian specialty. This is because only a portion of the components are present in the composition (stone flour is used as a filler). Moreover, the Moroccan-inspired finish stands out for its thin layer of crushed silk.

Layers with structural compositions are at least as big as the filler granules. Take the well-known bark beetle finish, which is applied using roller compositions. By the way, the maximum thickness for a bark beetle is determined by the size of the grain. Compared to facades, compositions with a lower fraction of filler are utilized indoors. With regard to travertine plaster, the same is true.

Pebble coatings and textured finishes are the "thickest" decorative materials. The former’s thickness can vary greatly, reaching up to 5 cm. For instance, replicating a wooden surface, brickwork, or wave relief. The size of the stone grains determines the size of the pebble plaster layer, for instance, mosaic.

The durability and smoothness of any surface are greatly influenced by the thickness of the wall plaster. Plaster adheres well, offers a smooth finish, and provides sufficient protection against moisture and cracks if it is done correctly.

Although the optimal thickness can change based on the kind of wall and the materials utilized, most interior walls should have a thickness of between 10 and 20 mm. This range is well-balanced in terms of offering sufficient coverage while preventing peeling or cracking.

You can attain a durable, expert finish that improves the look and usefulness of your walls by paying attention to the plaster thickness and adhering to best practices.

Video on the topic

Putty thickness

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

What can be the thickness of plaster

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

Plastering in a thick layer

12 MISTAKES of plastering walls that you need to know. How not to ruin the repair at the very beginning?

Minimum and maximum layer of plaster