How to prepare walls for plaster?

Plastering your walls is an important way to guarantee a smooth, long-lasting finish. The success of your project can be greatly impacted by proper wall preparation, regardless of whether you’re building a new home or remodeling an existing one. We’ll walk you through each crucial step in this post to get your walls ready for plastering so the finished product is perfect and long-lasting.

It’s crucial to realize that wall preparation entails more than just surface cleaning before you start. Examine the walls for any damage, cracks, or uneven spots that require attention. This preparatory work guarantees correct plaster adhesion and guards against future problems.

Eliminating any old wallpaper, loose paint, or debris from the walls is one of the first things to do. You can use a wire brush, sandpaper, or a scraper for this. After cleaning the surface, you must wash the walls with water and a light detergent to get rid of any grease or dust. For the plaster to adhere to the surface, it must be clean.

The next step will be to fix any holes or cracks in the wall. These imperfections can be filled in with a filler or patching compound and then smoothed out with a putty knife. You may need to use mesh tape or reinforcing mesh to add extra support for larger cracks or damaged areas.

It’s time to apply a primer or bonding agent after the repairs. For smooth or non-porous surfaces, this step is especially crucial because it improves plaster adhesion. Apply the primer according to the manufacturer’s instructions, and give it time to fully dry before proceeding to the plastering step.

Making the necessary preparations for your walls will lay the groundwork for a successful plastering project. You’ll be able to achieve a professional finish that improves the appearance and longevity of your walls with surfaces that are clean, smooth, and primed. Let’s examine each step in more detail to make sure your walls are ready for plastering.

Stages of preparatory work

Plastering walls requires a number of steps, including a series of sequential works.

1. The pre-preparatory stage: all wall-related construction and installation work must be finished at this point (in compliance with SNiP and GOST, which regulate plastering work in new buildings, this type of work must be implemented as a priority):

  • the floor covering has been laid, or in extreme cases, the floor screed has been poured;
  • work on laying hidden wiring was completed (grooves were punched and sealed);
  • door and window frames installed;
  • built-in furniture installed.

Prior to beginning the major work, plastic film is placed over the floor covering and masking tape is used to seal the floor and ceiling where they meet the wall.

  • First stage: the walls are cleaned of old plaster, paint, wallpaper, putty and various fasteners: nails and screws.
  • Second stage: repairs and strengthening of walls are carried out. Chips, peeling are removed, cracks are repaired.
  • Third stage: the walls are cleaned of oil stains, soot and other contaminants.
  • Stage four: work is being carried out to ensure adhesion between the wall and the plaster.
  • Fifth stage: beacons are installed.

Plastering walls is an essential step in achieving a smooth, long-lasting finish. To begin, give the walls a thorough cleaning to get rid of all dust, oil, and loose materials. Next, use an appropriate filler to fix any holes or cracks. If the surface is non-porous or smooth, use a bonding agent to improve the plaster’s adhesion. Lastly, to avoid the plaster drying too quickly and cracking, make sure the wall is slightly damp before plastering. By following these steps, you can lay a strong foundation for your plaster and achieve a polished finish.

Tools

A proficient builder ought to possess an extensive assortment of instruments to ready the surface for applying plaster. Their set is different for every particular case. Everything depends on the kind of coating being removed from the wall, such as paint, wallpaper, or plaster, as well as the materials used to build the wall:

Some tools are not necessary when working alone. For each type of work performed, a list of required tools, fixtures, and materials will be provided to make it easier for a novice builder to navigate.

Please be advised that without a portable ladder or specialized platform, the work cannot be completed (gantry). Consequently, there won’t be any more discussion of this gadget.

First stage: cleaning the wall of wallpaper, paint and old plaster

Old plaster, wallpaper, and paint must be removed from the walls before plastering can begin. If this isn’t done, the new plaster will either not adhere at all or will peel off over time. Every kind of coating that is removed from walls has a unique cleaning system.

Removing plaster

Regarding old plaster, there are two opinions:

  1. Removed only where it does not adhere well. Such places are determined by tapping the wall with a hammer. A loud sound indicates a loss of adhesion of the plaster layer to the wall;
  2. Removable completely.

Keep in mind that the first choice usually works. However, where is the assurance that this specific house (apartment) fits within this range? Therefore, even though it is a labor-intensive process, it is preferable to remove the old plaster completely in order to avoid taking any chances. A hammer, a chisel, a set of spatulas, and a brush are needed for this.

You can use a jail nozzle punch to speed up the process, but this works only on concrete and brick walls. A drill equipped with a shock function is necessary for aerated concrete. A metal brush is needed to thoroughly clean the wall of any remaining plaster residue.

If there is an electric drill or grinder, using a special nozzle with metal bristles will greatly speed up the work. Additionally, bags (not necessarily new ones; you can use them; much less expensive) must be purchased in advance in order to clean the fractured plaster.

To prevent accidental short circuits, the room is de-energized before the plaster is cleaned. The extension cord is used when working with power tools.

With a spatula, the thick layer plaster mortar that has started to peel and warp can be easily removed from the wall. Using a hammer, the tool’s blade is pushed beneath the loose plaster and brought down.

If thin layer plaster is painted over with a paintbrush dampened with water, it will come off easier. Until all of the plaster is wet, the wetting process needs to be repeated. Water is occasionally substituted with an electric drill fitted with a brush attachment. However, in this instance, a great deal of fine dust will seep into every crevice.

Expert builders remove all of the dust using a special hose after sanding a thin layer of plaster with a sanding machine and construction vacuum cleaner. However, this is a very costly pleasure and is not advised for do-it-yourself projects.

In all other situations, a hammer drill or a hammer and chisel are used to remove old plaster.

For information, when preparing the walls for decorative plaster with your hands, the façade of a building is cleaned of old plaster using the same techniques.

Removing wallpaper

It doesn’t seem like much work to remove the old wallpaper from the wall. But this is just an initial impression. You could need to spend even more time than with plaster if you just start taking them out. The procedure won’t take long, though, if you are familiar with some of the subtleties of this kind of work.

1. How can outdated wallpaper be swiftly removed from a wall? With a spatula or regular knife, they are simple to remove if they have been in service for more than eight years. What matters most is that their blades are sharp. The lagging regions are penetrated. The old paper is slowly torn off the wall with a spatula inserted into the slot beneath the wallpaper; suddenly, it breaks. Using a knife blade or spatula, scrape off the remaining wallpaper on the wall. Wetted areas with old wallpaper are removed if separation becomes problematic.

How can non-woven or vinyl wallpaper be swiftly removed from walls? A knife is used to cut them in the center of the canvas, and a wide spatula is used to separate the edges from the base. Next, rip off the bottom and top sections of the canvas with your hands. Using a metal brush, stains from the leftover wallpaper are eliminated.

2. How can paper wallpaper be removed from walls after only three to four years of use? Warm water dissolves the glue, making them simple to remove. Water must be able to pass through holes in waterproof wallpaper for the glue to stay wet. For this, there is a unique tool called the "wallpaper tiger." If you don’t have one, utilize a roller that has pointed tips.

You can use an ordinary knife as a last resort. It slashes across the wall’s whole surface. The water will seep beneath the wallpaper more quickly the more of them there are. In the event that water is unable to soften the glue, alternative solutions must be used.

You can treat PVA glue by using a laundry soap solution. It is broken up, mixed with three to four liters of water, and brought to a boil. Put it on the wall without letting it cool. You can use a paint roller or sponge for this. With a spatula, the wallpaper is easily removed after 20 to 25 minutes.

It is necessary to soak the PVA glue beneath the water-repellent layer in a solution of fabric softener and water. For a single-layer material, mix 0.2–0.3 liters of conditioner in 10 liters of water; for a multi-layer material, use 500–600 ml of water.

The product is applied to about 2 square meters of walls; it dries quickly, and the wallpaper needs to be removed after 20 minutes because it becomes well saturated during that time. You can remove old wallpaper one piece at a time and wet the areas every ten minutes to expedite the process.

Using a wide-bladed spatula, remove the moisture-impregnated sheets. Using a wire brush, remove any remaining wallpaper after moistening it with plain water.

Important: To remove any last traces of the solution, walls that have been treated with soap or conditioner must be rinsed multiple times with warm water.

3. How can wallpaper that has been adhered to walls using contemporary, premium glue be removed quickly? For these objectives, you require:

  • iron;
  • linen or cotton towel;
  • a bucket of water.
  • the towel is wetted, twisted and applied to the wallpaper;
  • the iron is connected to the mains using an extension cord and set to maximum power;
  • iron the towel 5-6 times with a heated iron;
  • the towel is removed;
  • wallpaper can be quickly removed with a spatula.

Not every novice builder has a steam generator or steam cleaner, but you can use one. Thus, even though the entire process will take much longer, an iron is the best choice.

Wallpaper that has been covered with a water-repellent film is removed with steaming, and the task is then completed as directed. Using a spatula or coarse sandpaper, remove any remaining paper that did not come off during steaming.

4. Hot water is sprayed on liquid wallpaper. They can be removed with ease with a spatula or they will fall off on their own after two hours. You can employ any of the previously mentioned techniques if they continue to fall behind the wall.

5. Because water just cannot pass through glass wallpaper, it can be removed with specialized removers like "KLEO." After applying a solution, the walls are left for a number of hours. The canvas is cut beneath the ceiling and pulled down once it has swelled. Even though the wallpaper is thick, one person’s strength is sufficient to rip it off the glue.

A word of caution: you must pull one canvas at a time, from top to bottom.

If swelling does not happen for some reason, the purchased solution is poured into the wallpaper after incisions are made with a knife. Using two narrow and wide sharp spatulas, the fiberglass wallpaper starts to come away from the wall after 15 to 20 minutes.

Removing paintwork

Plastering walls over painted or whitewashed surfaces is theoretically impossible because there is no adhesion at all between the plaster and the paint. Thus, one of the most crucial steps in getting the wall ready for plaster application is scraping off the paint layer.

How can I paint over old paint on walls quickly? Three options are available to you:

  1. chemical;
  2. thermal;
  3. mechanical.

Using specialized removers, such as "Prestige" gel, which can remove any kind of paintwork, is part of the chemical method. But it has a lot of drawbacks:

  • all types of drugs are very expensive;
  • only one layer is removed – if the wall has been painted several times, it will have to be treated the same number of times.
  • pungent, poorly ventilated odor;
  • solvent waste requires special disposal – flushing it down the toilet is strictly prohibited;
  • work should be done with full protection of exposed parts of the body;
  • After completing the process, you need to take a shower to wash off any remaining solution.

In conclusion, it’s best to stay away from this kind of paint removal.

It has long been known that walls can be painted over using the thermal method. Years of testing have shown that it never fails. The concept is straightforward: use a hairdryer to warm a coat of paint until bubbles appear, then remove with a spatula. Reheated and removed it once more. A blowtorch can be used for heating, but proceed with extreme caution as the paint may catch fire from an open flame.

An iron passed through newspaper can be used to heat paint if the layer is thin. However, there are drawbacks to this approach as well:

  • the paint removal process takes a long time due to heating of a limited part of the wall;
  • working with heating devices near electrical wiring, sockets, switches and other fusible materials is prohibited;
  • the paint layer can catch fire;
  • Oil-based paint emits caustic fumes when heated.

Paint removal by mechanical means first appeared at the same time as itself. With the available tools, it is easy to accomplish. Since it is non-toxic, paint in the kitchen, bathroom, or nursery can be removed using this technique.

How can paint be manually removed from walls? An ax and a bucket of water are required. After scoring the paint with an ax, liberal amounts of water are applied to the wall. An ax can be used to easily remove the paint coating after five minutes, once the wall has been soaked by the moisture. The tool must be used nearly parallel to the wall. A narrow spatula can be used in place of an ax in tight spaces, such as those close to the switch and socket.

Both wooden and brick walls can be treated with this technique; however, with brick walls, you will need to keep sharpening the ax. Concrete walls are not a good fit for this technique because paint particles get into the pores and stick to the wall very strongly.

How can old paint be swiftly removed from concrete? An electric drill equipped with wire attachments can be quite helpful in this situation as it effectively removes paint (a special chain is also used).

Stage two: wall repair

The walls go through a comprehensive inspection following the removal of the plaster or finishing coating. They might have masonry joint damage, chips, cracks, etc. Every flaw needs to be fixed.

Concrete floor repair and reinforced concrete wall panel repair are exactly the same, as is covered in detail in the work "Preparation of the base for floor screed," specifically in the section "Priming of concrete."

When working with bricks, loose bricks need to be taken out and the cement mortar needs to be beaten off the top and sides. Next, place the bricks once more on a polyurethane foam or cement-sand mixture. Large cracks are reinforced with self-tapping screws, small cracks are expanded (the operation is carried out to penetrate the mortar into the crack), and the large cracks are treated with "cement laitance" (it must be prepared from 1 part cement to 1 part water; you can use commercial deep penetration primers instead of milk).

Priming ensures adhesion between the repair mortar and the cracked edges, preventing further destruction of the edges. A repair solution is used to seal the cracks after the primer has dried. The method for repairing chips and unevenness is the same: after applying "cement laitance," they are sealed with mortar. Either make your own repair solution or purchase a pre-made blend.

For comparison, "cement laitance" is significantly less expensive than using a commercial primer to prime cracks, but the outcome is the same.

Cement and sand mortar is primed and sealed after the seam is dug down two to three centimeters to address masonry mortar issues. It is possible to substitute a very effective polymer-based repair composition for the cement mixture. However, the cost of the material is ultimately what matters—cement-sand mortar is significantly less expensive.

Putty based on gypsum is used to reinforce and seal aerated concrete that has minor internal damage (non-through cracks) (for example, Knauf HP Fin gypsum finishing mixture).

Third stage: cleaning the walls from dirt

Plaster’s adherence to the wall surface is weakened by soot, paint residue, and other impurities. It’s best to get rid of them. A metal brush is used to remove regular dust and dirt as well as solution residues.

Oily clay can aid in the removal of oil residue. It is applied thickly to the infected areas and allowed to dry. After removing the clay that has absorbed the fat, the process is repeated until the stains are gone. Oil stains on wooden walls should be removed by experts as they will eventually seep through and erode the plaster.

If oil cannot be entirely removed from brick and concrete walls using clay, the walls are treated with a 3% hydrochloric acid solution (some experts advise using a more concentrated composition – 5%). The walls are cleaned and then repeatedly cleaned with clean water.

Another method for removing grease stains from brick walls is to use a hammer and chisel (perforator). With cement mortar, the ensuing depressions are sealed.

Stage four: ensuring adhesion

The problems with establishing favorable conditions for the plaster mortar’s strong adherence to the wall have been addressed at this point. Since the adhesion of different surfaces varies, different wall types require different technological solutions.

Concrete barriers. Prior to the development of penetrating primers, concrete walls had a mesh fastened to them to ensure the plaster layer adhered to the wall as needed. Now that the procedure is much more straightforward.

After making notches on the wall that are 5 mm deep and 5–10 cm long with a chisel and hammer (axe, perforator), a layer of penetrating primer is applied using a roller or brush. Thus, multiple issues are resolved simultaneously:

  • the wall is saturated with moisture and does not draw it out of the plaster mixture;
  • the primer creates a film on the wall, which is a kind of glue between the concrete and the plaster mortar.

Walls made of brick. Using a chisel and hammer, notches are made in the wall (perforator, trojan, gear). A centimeter can be dug into masonry joints.

It only takes these two easy steps to guarantee that the plaster mortar adheres well to the brick wall. Many professionals advise applying a penetrating primer to the brick as well. Fathers’ and grandfathers’ experiences demonstrate that this is a needless procedure.

Concrete with air. Several options are provided to guarantee plaster adherence to the wall:

  • use a chainsaw to cut recesses in the wall that will hold the solution;
  • treat aerated concrete with special penetrating primers;
  • attach the plaster fiberglass mesh to the wall using glue.

A plaster mesh is more appropriate, according to many experts. In the work "How to plaster walls made of aerated concrete," the technology used to attach it to the wall is covered in detail.

Important: It is essential to attach a plaster mesh underneath the plaster if the wall composition is heterogeneous, i.e., combinations of brick and concrete, brick and aerated concrete, etc. The mesh is fastened with nails to wood, dowels and screws to concrete, brick, and stone bases, and welding to metal.

Plastering wooden surfaces has specific requirements when it comes to preparation. Plastering straight onto a wall is not possible because the solution does not adhere to wood. Output in wall covering that is continuous:

  • fiberglass or plastic mesh;
  • wooden shingles;
  • reed mat.

An ancient, tried-and-true technique for plastering plank materials is wooden shingles. It is made up of 1-2 m long, thin wooden slats. positioned with a 45-degree angle on the wall and a roughly 45-mm space between each slat.

The floor’s lower shingles are nailed first, followed by the upper shingles. It is preferable to wet the slats to avoid the nails splitting them. To prevent the shingles from tearing the plaster due to temperature changes, there should be a space of roughly 2 mm between the ends of the slats.

The work "How to plaster wooden walls" goes into greater detail about the technology used to fasten laths.

It should be noted that there is no distinction between wall preparation for textured plastering and simple plastering. Consequently, the response to the query regarding wall preparation for ornamental plaster is provided above.

Step Description
1. Clean the Walls Remove dust, dirt, and old paint from the walls. Use a brush or vacuum to ensure the surface is clean.
2. Repair Cracks and Holes Fill in any cracks or holes with putty or filler. Smooth the surface with a putty knife and let it dry.
3. Apply Primer Apply a coat of primer to the walls. This helps the plaster adhere better and ensures a smooth finish.
4. Check for Dampness Make sure the walls are dry. If there"s any moisture, use a dehumidifier or wait for the walls to dry completely.
5. Mark the Surface Use a pencil or chalk to mark any areas that need special attention or leveling.
6. Protect the Area Cover the floor and any fixtures with plastic sheets or drop cloths to protect them from plaster splatters.

Plastering walls is an important step in achieving a smooth, durable finish. Plastering requires careful surface preparation, repair, and priming. These steps set the groundwork for a successful finish. Poor adhesion, uneven surfaces, and cracks can result from rushing through or omitting these steps.

To start, give the walls a thorough cleaning to get rid of any dust, oil, or loose paint. This guarantees correct plaster adhesion. Next, look for any damage on the walls. Before smoothing the surface with sandpaper, use an appropriate filler to seal any holes and cracks and let it dry completely. This will give the plaster a firm, level foundation.

Painting the walls is a crucial stage that must not be disregarded. A high-quality primer will provide surface sealing, slowing down the plaster’s rate of drying, and improving adhesion. Select a primer that works well with the kind of plaster you want to use, then evenly apply it to the whole wall.

Your walls are prepared for plastering once they have been cleaned, repaired, and primed. Plastering will go more smoothly and look more professional if these preparatory steps are followed. You can achieve a smooth, long-lasting finish that improves the appearance and feel of your room with well-prepared walls.

Video on the topic

Preparing walls for plastering

Preparing walls for gypsum plaster knauf MP75.

Preparing a monolithic wall for plastering Which method is better! Part 2

Preparing walls for plastering. Removing plaster with your own hands! How, what?

Preparing the base | How to prepare the base for plastering

How to avoid cracks on the walls? Preparing for plastering. #11

Plastering a house as a stage of pre-finishing in a Sumarokovo house

What factor is most important for you when choosing materials for building a house??
Share to friends
Milan Yashina

Design engineer, specialist in development of design documentation. I will help you correctly design your home or other building.

Rate author
StroyArsenal62.com
Add a comment