Plastering the walls of the basement and cellar

A vital step in maintaining the longevity and aesthetics of these frequently disregarded areas is plastering the walls of the cellar and basement. Plastering gives your basement a sturdy, smooth surface that improves both functionality and appearance, whether you’re painting your space or trying to increase moisture resistance.

The walls of basements and cellars face particular difficulties, like increased humidity and possible water leaks. In addition to helping to conceal flaws, proper plastering is essential for establishing a moisture barrier. This procedure is crucial for long-term maintenance because it can stop structural damage and the growth of mold.

We’ll go over the essential methods and supplies required for plastering these areas successfully in this guide. You’ll learn how to achieve a polished finish that will last for years, from preparation to application. Plastering is a great way to make your cellar or basement a useful and visually pleasing area.

Aspect	Description
Purpose	Plastering the walls of the basement and cellar helps to protect against moisture, improve insulation, and create a smooth surface for painting or finishing.
Materials	Common materials include cement-based plaster, gypsum plaster, and waterproofing additives. Cement plaster is often used for its durability and moisture resistance.
Preparation	Ensure walls are clean, dry, and free from any loose material. Repair any cracks or damage before applying plaster. Apply a primer if necessary.
Application	Apply a base coat of plaster, allow it to dry, then apply a finishing coat. Use a trowel to smooth out the surface. Multiple coats may be required for a smooth finish.
Drying Time	Allow each coat to dry completely before applying the next. Drying times can vary based on humidity and temperature, but typically range from 24 to 48 hours per coat.
Maintenance	Check for any signs of damage or moisture issues regularly. Repair any cracks or peeling to maintain the integrity of the plaster.

Reasons for the appearance of excess moisture in the cellar

High humidity is a common issue that people run into when they decide to renovate their basements. The building’s design conceals the causes of its occurrence. A basement is an underground level of a building that is buried more than half of its height. The soil on the outside and the interior air on the inside are in contact with the cellar walls. There are two possible outcomes from this proximity to two environments with different temperature and humidity indicators.

To find the sources of the excessive moisture, there is an easy method to install either inside or outside the publication. We firmly secure a piece of polyethylene against the wall. We examine which side the moisture formed after five to seven days.

Poor waterproofing is the cause if it is on the side that is in contact with the wall; however, if it is on the surface that faces away from the wall, the issues within the room are resolved. Waterproofing the plaster on the cellar or basement walls can help with these issues to some extent.

Formation of condensation

If the building itself is the cause of the wetting of the enclosing structures, then inadequate ventilation or inaccurately calculated thermal insulation are the likely culprits.

The above-ground portion’s natural ventilation is a feature that basement rooms cannot claim. Vents and other small windows are the most that can be used during the design and construction phase, particularly if no other rooms were intended except for a storage room. A small amount of fresh air is brought in, the buildings breathe, the moisture in the building materials evaporates, and people who regularly breathe and perspire come in.

When the concentration of dissolved water in the basement air surpasses the critical value, the extra water condenses and forms droplets on the surfaces. In order to ensure air exchange, this issue needs to be fixed, starting with the supply and exhaust ventilation project.

The term "dew point" comes into play if we are discussing poorly executed thermal insulation. This temperature is the point at which atmospheric water vapor starts to condense into dew. It appears to be quite lovely and nothing at all awful. When this value is reached in the wall’s thickness rather than the air, problems start to arise. Take into account the following scenario, for instance: Winter is upon us.

The temperature inside the room is heated, but outside it is already very cold—either the ground is frozen or has warmed up slightly. Concrete’s (as well as many other materials used for basement walls or foundations) basic structure presupposes the existence of air-filled pores. The earth cools the wall’s exterior while heating its interior.

A specific curve represents the temperature changes in the thickness. The depth at which the temperature reaches the dew point is determined. Here, the capillary tension forces act throughout the structure, causing the water vapor to settle and spread through the pores. The material becomes moist, heat transfer rises, and the area where condensation forms widens.

When moisture reaches the outer edge of a frozen ground, it freezes and ice floes break the pores, causing the structure to gradually collapse. Plaster and other finishing materials peel off if water gets to the inner surface. Calculations using thermal engineering are used to make sure that the dew point is reached in a layer where it won’t be as critical, allowing water to evaporate without condensing inside the structures.

Water penetration through the wall

Waterproofing the basement walls and foundations is required even in situations where the soil surrounding the building has been drained and groundwater is located beneath the foundation sole.

The soil surrounding the building contains a significant amount of liquid, including runoff, precipitation, groundwater, and some moisture left over after watering plants. Condensation collects in the sand even in dry desert environments.

That is to say, water exists regardless; its amount and kind solely dictate the choice of waterproofing and, in the lack of a covering, the kind and rate of structure degradation.

You will find water traces inside more quickly the greater the volume and pressure of water coming in from the outside, but the location of the traces will also be more specific. It will be more challenging to pinpoint the issue if moisture seeps through tiny gaps in the waterproofing layer or if there is insufficient of it. Moisture then spreads along the wall in all directions.

Suppose, for budgetary reasons, that waterproofing was not included during the construction phase, or that the material used was inappropriate and deteriorated as a result of shrinkage movements. The protective coating needs to be restored in this situation, or applied for the first time, and modern technologies make it possible to accomplish this both indoors and outdoors.

And only then start painting the walls of the basement. If cracks started to appear and open between the wall blocks during shrinkage deformations, the situation could get worse. You run the risk of owning your very own Bakhchisarai fountain in this situation, but it won’t make you happy. Here, the masonry needs to be repaired.

How to get rid of excess moisture

Determining the causes of the excess moisture’s appearance is the first step in combating it.

The following is the action algorithm:

1. Determine whether the cause of the problem is outside or inside the premises.
2. If outside:
3. we determine the presence and size of cracks in the masonry or monolithic concrete;
4. we try to find out the condition of the external waterproofing and the fact of its presence or absence (design documentation, communication with the contractors, former owners of the building, etc.). d.);
5. we repair the structure, restore the waterproofing layer, internal waterproofing can be done with penetrating compounds.

• we check the condition of the ventilation;
• we collect information about the "pie" that makes up the walls, not forgetting about the air gaps;
• we develop a supply and exhaust ventilation project that takes into account the functionality of all basement rooms, we make a heat engineering calculation, additional cladding of the basement walls may be required.

What kind of plaster is used in the basement

One of the following types of plasters is used to finish the basement walls:

Finally, based on the operating conditions, the preferred option is chosen.

Cement option

Only rooms without walls in direct contact with the ground and without an abundance of moisture can use plaster mixes made of general construction cement. High-quality external waterproofing is a must to keep the basement’s structures dry beneath the plaster layer.

Although it is preferable to use factory-made mixtures, you can prepare cement-sand plaster yourself to save money. Because their recipe has been validated, the outcome will be more consistent. It is necessary to dilute the powder with water in the manufacturer’s recommended ratio prior to application.

Moisture-resistant plaster

Water-repellent additives are used in moisture-resistant compositions to enable the coating to resist direct water ingress in addition to unintentional splashes. Plaster mixtures on a gypsum binder can also be used for this. For finished dry basements, where waterproofing consistently protects the walls, moisture-resistant plasters are the better option.

In other words, the plaster won’t be harmed if water is spilled on a surface covered in this way and it quickly runs off. Problems could occur if it stays on the surface for an extended length of time or if it wasn’t a glass but rather a pressurized stream from a hose. Using waterproofing plasters is the better option in this situation.

Waterproofing mixtures

In addition to being resistant to moisture, waterproofing plaster mixtures can tolerate pressure equivalent to a 5-meter water column. These kinds of compositions are applied to pool bowls, fountains, etc.

The building will be protected from moisture intrusion if the mixture is used as the only waterproofing layer and is placed inside the walls; however, the foundation walls will become saturated with water and eventually collapse. The fix is only going to last temporarily.

This is a great choice for a protective layer on the visible portion of the foundation wall that protrudes above ground, allowing for additional finishing (tiling, stone, painting).

A great video about using waterproofing

Sanitizing composition

After application, sanitizing compositions create a lot of pores. They may make up up to half of the total volume. These are multi-layer compositions, where the waterproofing layer is usually the first layer and the sanitizing layer is the second. The following rule must be followed when selecting additional coatings: each layer should have larger pores than the one before it in order to preserve the plaster’s drying qualities.

The surface area multiplies multiple times because of the large number of pores, which greatly speeds up the process of evaporating extra moisture. Sanitizing compositions also shield the finish from efflorescence by retaining salt particles in their large pores, which cause them to crystallize.

Sanitizing plaster for basement walls can shield the building from external moisture since it has a preliminary layer of waterproofing. Hydrophilic additives also remove water from the treated structures, which dries them out.

Plastering tool

The plastering tool used in the basement is the same as the one used in other rooms:

• Spatulas.
• Trowels, floats and half-floats.
• Ladles.
• Beacons and rules.
• Mixer.

Application mechanization is achievable with the use of specialized machinery.

Preparation of the wall surface

Once the source of the excess moisture has been identified and removed, you can start the preparatory work needed before plastering.

1. All peeling fragments of the wall and its coating are removed.
2. Oil and bitumen stains must be cleaned.
3. If there are traces of fungus, they are removed with a hard metal brush, after which the affected area is treated with an antiseptic.
4. Efflorescence is also cleaned and treated with special neutralizing compounds.
5. Seams and cracks are deepened, widened, notches are allowed on the surface of the walls.
6. Be sure to remove dust from the surface. This can be done with a vacuum cleaner or dust-removing compounds that bind small particles, turning them from potential culprits of peeling into soil that increases adhesion with roughness.
7. The surface is primed. The primer is selected based on the conditions of use.

Deep recesses may be initially sealed with cement-sand mortar.

The major objective of plastering cellar and basement walls is to produce a strong, moisture-resistant surface that adds a clean finish while guarding against moisture. In addition to making the area appear better, proper plastering also helps to avoid problems like mold and water damage. You can keep your cellar or basement dry, usable, and ready for use by using the proper supplies and methods.

Step-by-step guide to applying the finish

After the prepared surface has dried, the basement’s plaster is directly applied. The compositions applied in layers should ideally come from the same manufacturer. If this requirement is not fulfilled, there could be a chemical reaction between the layers that destroys the finish.

Read the manufacturer’s instructions as listed on the packaging.

1. Installing beacons.
2. After determining the thickness of the plaster layer, we fix reinforcing meshes on the wall surface, immersing them no more than 2/3 of the depth. This step is mandatory in new houses, as reinforcement will reduce the load from deformations, protecting the finish from the appearance and expansion of cracks.
3. Prepare the composition in accordance with the instructions so that it can be used in 1-2 hours. Mix thoroughly with a mixer.
4. Apply the plaster mixture in one or more layers (depending on the thickness and type of plaster). Each layer is applied after the previous one has dried.
5. After application and the first setting (15-25 minutes), the surface is rubbed to make it smooth. When using sanitizing compounds, this step should be skipped, since the procedure will close the pores, that is, reduce the advantages of the coating to zero.
6. Next, the plaster must be allowed to dry in accordance with the recommendations on the packaging. Compliance with the requirements for the maturation conditions of the coating guarantees that the resulting plaster layer will have the characteristics declared by the manufacturer. Additional care may be required at this stage (covering with films, moisturizing).
7. After 7-15 days, you can proceed to further finishing of the plastered surfaces.

Utilizing a trowel to grout the plaster

What to do if the material does not dry for a long time

When the plaster on the walls in the basement is drying, the biggest temptation is to speed up the process. Here, though, you must adhere to the directions exactly. Cracks may appear if the leveling layer dries faster than expected. Avoid using heat guns to dry the area because building mixtures often require a humid atmosphere to gradually gain strength.

Installing supply and exhaust ventilation will initiate air circulation in the basement, which will speed up the plaster layer’s drying process. Nevertheless, drafts must be prevented at all costs.

Main mistakes when plastering walls

The primary error was deciding to finish right away rather than try to solve the problem in the presence of too much moisture in order to save time and money. Non-adherence to the application and drying technology of the chosen mixture is linked to additional errors. It’s crucial to carefully read and abide by the manufacturer’s recommendations.

Plastering basement and cellar walls successfully not only improves these frequently ignored spaces’ appearance but also offers essential protection against moisture and structural problems. You can guarantee a strong and long-lasting finish that will withstand the particular difficulties of these areas by selecting the appropriate plaster type and using the right application techniques.

A smooth and successful plaster application depends on proper surface preparation, which includes cleaning and fixing any damage or cracks. During this stage, meticulous attention to detail can have a big impact on the final result and durability of your plaster job.

Keep in mind that keeping your basement and cellar in excellent condition for years to come requires routinely inspecting and repairing the plastered surfaces. Plastering these areas can improve your home’s appearance and functionality with the appropriate technique.

Video on the topic

How not to build a cellar .Where does condensation collect in the cellar?

Cement-sand plaster in the basement

Waterproofing the cellar in the garage (a month of work in 20 minutes)

Layers of 10 cm. Plastering the basement.

Plastering the walls of the basement

plastering the basement. throwing mortar on the walls