How and how to plaster walls in an apartment under wallpaper

The first step towards achieving a smooth, even finish in any room is plastering the walls. Whether you’re working on a newly constructed apartment or renovating an older one, good plastering guarantees that the wallpaper will stick well and look great for many years to come.

The final look of your walls can be greatly altered by selecting the appropriate plaster and applying it correctly. Depending on the state of the walls and the kind of wallpaper you want to use, there are various plaster types and techniques to take into account.

This post will walk you through every step of the process, from choosing the right supplies to learning the tricks that will leave your walls immaculate and ready for any wallpaper design you can dream up.

What to plaster walls under wallpaper

Because the apartment’s rooms, their conditions, the base material, and its state vary, choosing a plaster should consider more factors than just price. Not to mention the technology that will be employed.

For instance, specific compounds are needed for large-scale mechanized plastering. Lime is used less frequently than gypsum mixtures or cement compositions when manually leveling walls.

Since it is challenging for even professionals to achieve the desired surface quality of cement-sand solutions, putties are used in conjunction with cement-sand plasters.

For wallpaper of any thickness, gypsum plaster is used if the walls are composed of tongue-and-groove slabs, aerated concrete blocks, or plasterboard sheets.

Aspects taken into account:

1. The coating is light, not loading the base with its weight.
2. When setting, gypsum behaves more gently towards the base than cement. The gypsum mixture does not shrink, and the cement mortar contracts, internal stresses appear, which are transferred to the wall material.
3. The gypsum coating has properties close to the base material, during operation it behaves the same as the walls during temperature and humidity fluctuations.
4. The gypsum coating, due to the many small pores, does not block the breathing of wall materials.
5. It is better not to "push gypsum and cement together", because they conflict in the "chemical field". During operation, with direct contact, over time, the destruction of cement crystals occurs with substances released by gypsum. Delamination appears, pieces of the coating fall off. A separating layer will be needed to solve the problem of proximity.
6. Such a choice corresponds to the rule: the coating material should not be stronger than the base material.

Gypsum plaster works best for residential spaces, such as living rooms, bedrooms, and kid’s rooms. Gypsum is used in areas where a human-friendly microclimate is needed because it helps control humidity, moderate temperature swings, and reduce noise.

Plaster with a cement binder is preferred for non-residential buildings with concrete walls due to its strength, resistance to moisture, availability of cement and other components (if the composition is prepared independently), and less expensive cost.

Any composition is "accepted" by brick surfaces. For walls, it makes more sense to use mixtures with a gypsum binder if the brick is brittle and starts to crumble. For wooden walls, plasters made of clay or gypsum are applied.

These days, lime plasters are used less frequently.

Tools and auxiliary devices

Physically demanding plastering and preparation tasks are made simpler with the use of "correct" tools. It won’t be unnecessary to use small machinery to prepare the solution and apply the mixture.

To get the solution ready, you’ll need:

• containers (measuring, for the solution);
• construction mixer;
• trowel or spatula.

In order to get ready, use:

• falcon (used more often by craftsmen);
• trowel (with a stainless steel spatula);
• spatulas of different sizes;
• rule;
• half-graters, floats;
• brushes;
• plastering ladle (usually used by craftsmen to perform splashing);
• roller (for priming);
• level;
• cord;
• tape measure;
• masking tape (to protect surfaces not to be plastered);
• clean rags.

Apart from primers, putties, and dry plaster mixes (DS), prepare corners, beacon profiles, and reinforcing mesh as needed.

In order to ensure that the wallpaper adheres correctly and looks perfect, it is essential to plaster the walls of an apartment before applying wallpaper. This include choosing the appropriate plaster type, carefully applying it in thin layers, and smoothing it down to remove any flaws. These steps will help you make the ideal base for your wallpaper, which will ensure that your wallpaper lasts a long time and your walls are sturdy.

Criteria for choosing a plastering technology

Even among plasters created by experts, there are differences in the degree of roughness:

1. Cement-sand mortars are not suitable for gluing paper wallpaper, since even high-quality grout leaves a strong roughness. Thin wallpaper requires smoothing with putty.
2. Lime plaster made with a cover allows you to stick wallpaper with a thickened canvas, as well as duplex.
3. High quality surfaces can be achieved by processing gypsum plaster even without puttying, which is necessary for photo wallpaper, silk-screen printing.

Certain wallpaper styles don’t need such perfect surfaces:

• vinyl;
• glass wallpaper;
• non-woven canvases;
• liquid wallpaper.

The thickness of the canvas accounts for the first three types, while the characteristics of the material and the technology used to apply it account for the final ones.

As per the updated version of standards 3.04.01-87, known as SNiP, there are two types of surfaces that can be used for wallpaper adhesion:

1. K3 – under sheets on a paper or non-woven base, the presence of traces of processing with abrasive materials up to 0.3 mm deep is permissible.
2. K4 – any scratches are not allowed under glossy and metallized thinnest wallpaper sheets, there should be no shadows with side lighting.

The procedure for plaster walls for wallpaper

The steps involved in plastering a wall beneath wallpaper follow a similar order to that of plastering other types of finishing. Unless, that is, waterproofing is not applied.

Reinforcement and lighthouse installation are not always required. The latter is carried out using a plaster layer that is thicker than 15 mm (for gypsum) or 40 mm (for cement).

• Preparation of the base (to increase adhesion, strength, prevention of spots);
• installation of lighthouses;
• solution of the solution;
• applying (sequential) layers of the plaster mixture;
• grinding;
• Lighthouse removal;
• padding;
• putty;
• drying.

Preparation of walls

The surface is treated before you begin plastering the walls beneath the wallpaper.

1. If the wall is new, then after inspection it is cleaned of stains, metal protruding parts are cut off or isolated.
2. In brickwork, seams are expanded, deepening them by 1 cm.
3. Cracks and chips are repaired, protrusions are cut off.
4. Nots are made on the surface of concrete walls.
5. Existing dust is removed from the surface.
6. Primed.
7. Wooden surfaces are covered with laths.
8. If necessary, a plaster mesh is attached to the wall.
9. Dried.

Through these procedures, the surface’s adherence is improved and the finish is shielded from stains and microbial deterioration.

When it comes to fixing walls that have an outdated coating, inspection, strength testing, and layer removal are added to the top of the priority list.

Beacons

Plaster leveling, also known as rough plastering, requires the use of beacons if the wall is tilted or if the surface deviates from the plane by more than 10 millimeters. An additional vertical plane is formed when beacon profiles are installed in accordance with the level.

Depending on the plasterer’s experience and the length of the rule, the distance between the profiles can range from one to more meters. There are variations in beacon types and installation techniques. The precision with which the profiles are installed determines the final geometry.

Preparation of the solution

The kind of plaster underneath the wallpaper determines the preparation technique. Small amounts of mixtures are diluted because certain compositions, like gypsum, have a limited shelf life. Larger batches of solutions with a long shelf life can be made.

Gypsum solutions should only be mixed once, and always in a clean container, as even a tiny bit of leftover solution can cause the newly mixed mass to solidify too soon.

There is also a difference in the order of mixing. Water is filled with poured-in gypsum SS. Additionally, ready-made cement-sand SS. If the cement-sand mortar is prepared in a trough using specific ratios and you mix the cement and sand by hand, mix the dry ingredients first and then gradually add water.

To mix, a mixer is utilized. Using a shovel, the solution prepared in a trough is combined. Using a mortar mixer for large-scale mixing makes more sense.

Splash

The initial layer that is applied, intended to form a "buffer" coating. It guarantees that the base and the entire plaster coating will adhere firmly. This layer is not applied to gypsum plaster.

With a ladle or trowel, mix the less viscous lime and cement mortars before sprinkling them onto the wall. Instead of leveling the surface, the tool’s tip is used to create horizontal grooves for improved adhesion.

Covering

Give it time to set after applying (over the splash) and using a rule to level the soil layer. The beacons are then taken down, and a cover is applied (this step is skipped when plastering with gypsum). Compared to the primer dough, the cover solution is made less viscous and sanded. Small portions of sand are taken.

Using a wide spatula, apply a layer of no more than 5 mm thickness before the soil dries. A lime-gypsum coating works better for soil that is based on lime.

Grouting and ironing of walls

Graters are used to rub the coating just after it begins to set but before it dries. Before beginning, use a maklovitsa (water spray) to moisten the coating’s surface. The grout is applied flat and in a circular motion using the tool.

The pressure is stronger above the protrusions and weaker above the depressions. Rub in a run after circular grouting to achieve smoother surfaces. Consequently, the tool leaves no trace and the lumps of mortar are filled in.

A sand-free solution is used to give gypsum coatings a smooth surface. Distilled with an adhesive liquid is gypsum. Apply using a trowel in a zigzag pattern on a small (~0.5 m2) section of the wall while keeping the trowel blade at a 20–25 degree angle to the wall.

Next, add another layer and use the trowel’s edge in cross-directional motions to smooth it out "on the tear" without stopping. Similarly, plaster on lime can be smoothed with a lime-gypsum mass that has not been sanded.

The top of the layer is strengthened (compacted) by ironing. Plasters made of acrylic develop a gloss. Stainless steel-bladed spatulas or trowels are used for ironing; the tool is moved repeatedly and pressed against the plaster’s surface.

Putty

The surface is putty if the plaster on the walls beneath the wallpaper is not as smooth as desired, which is more frequently the case with cement compounds. The wall is primed before putty is applied. Two types of SS are produced by manufacturers for puttying: basic and finishing (with extra-fine filler grinding). Moreover, ready-made mass is available.

Using a spatula, apply the putty mixture in thin strips with a 6–8 cm overlap, up to 3 mm thick. The spatula should be used at a 45° angle. In the first pass, the base composition is applied, and in the second pass, the finishing composition. By using side light to illuminate the aircraft, quality is managed.

Plaster Type	When to Use
Gypsum Plaster	Ideal for smooth, level surfaces and provides a good base for wallpaper in living rooms and bedrooms.
Cement Plaster	Best for high-moisture areas like bathrooms and kitchens, ensuring durability under wallpaper.
Lime Plaster	Perfect for older walls needing breathability, commonly used in historic or rustic settings.

An apartment’s walls must be plastered correctly to provide a level, smooth surface that is ready for wallpaper. Although the procedure may seem difficult at first, it becomes simple and doable with the correct tools and methods.

Selecting the appropriate kind of plaster is essential. Take into account the intended finish and the state of the walls. Gypsum plaster’s smooth finish and ease of application make it a popular choice for interior walls. Before plastering, make sure the walls are ready by giving them a thorough cleaning and using the appropriate primer.

Plaster must be applied in thin, even layers to ensure a perfect surface and prevent cracks. To smooth out any blemishes before the plaster sets, take your time. A quick sanding after it dries will help create the ideal foundation for your wallpaper.

Plastering your walls under wallpaper can completely change the appearance of your apartment and provide a strong base for the design you’ve chosen with a little perseverance and attention to detail.

Video on the topic

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