Plasterboard for painting and wallpaper

Recommendation points

• Do I need to putty
• Differences between gypsum mixes
• Preparation of sheets for puttying
• Sealing straight and corner joints
• Installation of corner profiles
• Leveling walls with gypsum plaster

Plasterboard finishing solves the main problem and gives the walls good geometry. All that remains is the final smoothing and surface treatment, joint sealing and corner protection. Our small educational program will tell you about how to putty drywall correctly.

Do I need to putty

In some cases, puttying is not required. For example, if drywall serves only as a preparatory coating. So, quite often a sandwich is attached on top of the gypsum board for interior decoration, protecting it from punching, improving sound and thermal insulation. A more common case is to lay ceramic tiles on drywall-lined walls. In any case, the preparation includes a thorough priming and preliminary grouting with an adhesive mixture, the joints will also not be superfluous to strengthen.

It is known that the thicker the wallpaper, the more gross defects they can visually hide. Of course, it is necessary to seal the seams and fastening holes in any case, but it makes absolutely no sense to putty the entire surface: it is already even. Naturally, the wall should be well primed so that there is no difficulty in tearing off the wallpaper. For the same purpose, when preparing walls for wallpaper, they are wiped with a thin layer of finishing putty with a more liquid consistency..

Painting, decorative puttying and other artistic finishing options (as a rule, they do not have their own basis) are the most capricious to the quality of the coating. The smallest cracks and scratches left after installation, and in some cases the color unevenness of the base must be eliminated. Proper preparation of gypsum plasterboard structures is of key importance, without it, even a high-quality plasterboard will lose its aesthetics..

Differences between gypsum mixes

The practice of preparation and puttying of gypsum boards includes a fairly extensive list of works, respectively, and the materials for them are diverse. The final leveling of the walls (not only the gypsum board) is performed with gypsum mixtures of two categories: finishing and starting.

The putty for starting leveling allows to eliminate significant violations of the geometry, it is allowed to apply it with a layer of 4–6 mm, and sometimes up to 10 mm. For a more accurate value of the layer thickness, refer to the information on the label. The starting mixture is easy to distinguish even visually: its structure is heterogeneous, contains inclusions of sand of different fractions.

The finishing putty, on the other hand, looks like a homogeneous and dense snow-white powder. The composition is mostly stucco, a small amount of natural impurities, plasticizers and activators. The layer of finishing putty is strong and dense, forming a thin crust on the wall, it smooths out fluctuations in temperature and humidity, due to which the gypsum wall does not walk as actively.

Preparation of sheets for puttying

It is necessary to sweep the sheets from dust and primer, of course, regardless of the decorative coating. There is also a practice of painting the caps of self-tapping screws so that rusty spots do not appear on the wall over time..

Papered, factory joints do not need pretreatment. The short ends of the sheets, on the contrary, require increased attention: their edges must be trimmed, forming a rectangular hollow. The joint is also dust-free and well-wetted with a primer.

Even when laying tiles and similar materials on gypsum board, the joints should still be repaired. This is usually done with a starting compound or its mixture with a finishing putty from the same series in equal parts. In the case of tiles, it is also allowed to seal with an adhesive.

Sealing straight and corner joints

The most vulnerable places of drywall walls are the joints between the sheets. Flat seams need to be reinforced with a mesh and this is done like this:

1. Apply a small amount of starter putty to the joint surface.
2. Cover the joint with a piece of paper tape.
3. Smooth with a spatula, squeezing out excess putty from under the paper.
4. Smooth the seam and smooth the surface with a wide trowel.
5. Repeat alignment if necessary.

Fiberglass mesh is best with paper tape. So the structure of the drywall sheet (paper + gypsum) is reproduced as identical as possible. The whole structure acquires monolithic uniform strength.

The difference in sealing fillet joints is in the use of a special tape with metal inserts. The composition is applied to the corner in the same way, the tape is smoothed, then alignment is performed.

There is a peculiarity of surface preparation for base coatings. Sealing of seams and self-tapping screws is best done with a starting compound. So the layer of finishing putty will have a uniform thickness and there will be no darkening at the joints..

Installation of corner profiles

The outer corners are refined differently. For these purposes, a perforated corner profile is intended. Before work, the seam needs to be slightly cleaned, moistened with a primer and filled in the groove between the sheets with a thick starting putty. A small amount should be left on the corner surface.

The corner is laid on a damp putty, pressed down and leveled. When the edge of the profile is leveled, remove excess filler and smooth the shelves with holes well. After a short drying time, the corner must be leveled with a wide spatula.

Leveling walls with gypsum plaster

It is easier than it seems to level spacious surfaces with putty. The angle of inclination of the trowel relative to the work surface is of key importance. Up to 35–40 °, the slope is considered smoothing and leveling, closer to the right angle the spatula will remove part of the wet layer.

For filling different areas, a trowel of the appropriate width must be used. The most versatile 450 mm spatulas, this width allows you to process areas of 1-1.5 m at a time².

The putty is applied to the wall in one wide, sweeping motion. The second movement removes the excess composition and stretches it further along the wall. After 3-4 applications, you can work with the same spatula or trowel, smoothing and leveling the composition, filling the resulting voids. You need to move first in horizontal and then in vertical rows, grabbing the previous one by about 1/3 of the trowel width.

Sometimes the walls are additionally protected from cracking by laying glass cloth or fiberglass mesh in the first layer of putty. This is done in about the same way as sealing the seams: the mesh must be applied to the damp wall and stretched with a spatula, and then carefully smooth the surface with a small amount of putty.

Layer thickness is a relative value. Choose it depending on the required degree of alignment, thickness and translucency of the final finish. The putty has good adhesion and can be applied in many layers. Typically, this is done by stretching the film 0.5–1 mm thick at a time. It is important to apply the putty in large areas when it comes to translucent decorative coatings: even putty from one bag can give a different color when dry. On the other hand, only the last application, the so-called whitening, can be carried out in a continuous layer..

Before applying finishing materials, the wall must be treated with fine emery paper to remove minor irregularities, then primed.