What Are Some Common Defects That Can Occur With Plastering, And How Can They Be Prevented?

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    The plastering phase of a building's construction is important and must be handled carefully. However, plastering imperfections are possible even with meticulous attention to detail.

    These flaws, which can be as minor as a hairline crack or as extensive as a collapse, can result from some factors, including poor plaster mixing, poor application methods, or exposure to the elements (including water and climate shifts).

    Here, we'll go over some of the most typical problems that crop up during plastering, along with some advice on how to head them off or fix them if they do.

    Types Of Plastering Defects

    Plastering is important in many building projects because it creates a uniform and attractive surface for paint or wallpaper to adhere to.

    Plastering is an essential process, but it can be difficult and time-consuming, and it's important to take your time to ensure everything runs smoothly.

    Improper surface preparation, low-quality materials, improper mixing ratios, and insufficient curing time can all contribute to a wide variety of defects, from purely cosmetic to more serious structural ones.

    Here, we'll go over the most common plastering flaws and offer advice on how to avoid or repair them for a professional-looking, long-lasting result.

    1. Cracks In Plastering

    The plastered surface develops cracks. These fissures can range in size and visibility from barely perceptible hairlines to obvious chasms. Crazing is the formation of tiny cracks.

    Plaster cracks can appear for various reasons, including temperature changes, surface discontinuities, building structural flaws, poor workmanship, excessive shrinkage, etc.

    You may have noticed that cracks in the plaster are one of the most common issues with the material. Unfortunately, many different types of cracks can appear on a plastered surface:


    It looks like a spider made a web out of tiny cracks.

    As a rule, they are relatively small and do not go through the plaster. Crazing occurs when the base absorbs water and fines build up on the surface, as happens when there is an excess of particles in the sand or when the plaster is applied on a dry basis.

    Crack With Hollowness 

    The hollowness of the plaster is what led to the crack. However, poor workmanship or adding too much water to the plaster mixture could also be to blame.

    Joint Separation Crack

    Common examples include brickwork and other places where different materials meet. The phenomenon is due to the action of differential thermal movement.

    2. Falling out of Plaster

    One or both symptoms may occur in flaking or peeling plaster.

    Flaking Of Plastering:

    Flaking occurs when a plastered surface develops tiny, loose particles. This often happens when the bond between coats of plaster is broken.

    Peeling Of Plastering:

    When surface plaster breaks off, a patch can be made. Plaster peeling is the term for this. It's also largely due to the bond breaking down between layers of plaster.

    Proper choice of materials and surface treatment may eliminate the need for these fixes. In addition, superior workmanship can help minimise adhesion inconsistencies.

    3. Bubbling And Blistering 

    Plaster blistering and bubbling can occur if the plaster is applied to a wet surface or if the plaster is overworked.

    If you want to avoid this issue, dry the surface thoroughly before you plaster it, and then apply the plaster in thin layers, giving each one time to dry before adding more.

    Remove the affected area and let it dry completely if bubbling or blistering occurs. After the first coat of plaster has dried, you can apply additional coats in thin layers.

    4. Efflorescence 

    Soluble salts in plaster ingredients and other construction materials like sand, bricks, cement, etc., cause plaster efflorescence. In addition, the construction site water supply may also contain soluble salts.

    During the drying process, the soluble salts in a freshly built wall are brought to the surface, where they can be seen as a white crystalline substance.

    Unfortunately, the efflorescence that results from this kind of growth greatly diminishes the patient's ability to adhere to the wall.

    The unsightly effect efflorescence has on a surface can be mitigated by repeatedly dry-brushing and washing it.

    5. Loose Plaster

    closeup hand worker plastering cement wall building house (1)

    Plaster displaced by material application, tapping, or other external forces is said to be "loose." Inadequate curing and improper mixing are the primary causes of this problem.

    It's possible to avoid it with the right mixture and enough curing. Having done a good job will help avoid this problem.

    6. Grinning

    If the mortar joints are visible through the plaster, it is acceptable to grin.

    This is caused by the loss of mortar joints and the resulting shift in the suction of both masonry units. Before applying plaster, an undercoat or spatterdash coat can cover up any smiles.

    7. Uneven Finish

    An uneven finish can result when the plaster is not applied evenly or when the surface needs to be properly prepared before plastering. First, ensure the plastered area is dry, clean, and debris-free to avoid this issue. Next, smooth out the plaster with a straight edge, and apply it evenly.

    If the finish isn't even, sand it until it's smooth and apply another thin layer of plaster, waiting for each one to dry.

    8. Popping Of Plastering

    The conical holes that form when plaster breaks are known as "popping." Contamination particles in the mortar mixture, like burned lime or other organic components, cause it.

    Particles that expand when set can sometimes be found in the plaster mix. A conical hole is created in the plastered surface before the particle. Blow or pop refers to the conical shape of the hole. To prevent the plaster from popping, check the mortar mixture to ensure it is free of foreign particles.

    9. Expansion

    This leads to layer cracking, spalling in the plaster, swelling, and softening.

    Usually, the buck stops with proprietary gypsum-based products. However, in the presence of water, the Portland cement paste reacts with the sulphate in the gypsum to form more stable compounds and more damage to the plaster.

    The only way to fix the expansion-induced disturbance that the gypsum in the mix caused was to replace the plaster with something else.

    10. Softness Of The Plaster

    That area of the plastered surface is soft due to the excessive wetness in specific spots. The primary causes of such a softness are too thin finishing coats, the presence of salts that melt when heated, excessive suction from the undercoats, and so on.

    11. Plaster Debonding

    Debonding of plaster refers to the process by which the plaster comes loose from the wall.

    It could have been caused by a plaster coating that was excessively thick, improper preparation of the substrate, or by a greasy, dusty, or dry substrate.

    When applying plaster, the following concerns must be addressed to prevent the plaster from coming loose. First, remove any dirt and grease from the substrate before beginning the plastering process. Allow sufficient time for the substrate to reach the ideal level of moisture. In cases where it is necessary, you should use bonding chemicals.

    12. Stains Of Rust On A Plastered Surface

    Rust stains on a plastered surface can be an eyesore and are a common problem that homeowners experience.

    Rust stains can be caused by a number of different factors, including metal objects coming into contact with plaster, damage caused by water, or prolonged exposure to high humidity levels.

    In the following paragraphs, we will discuss rust stains on plastered surfaces, including what causes them and how they can be avoided or repaired.

    Causes Of Plastering Defects

    Inadequate Surface Preparation

    Plastering defects of various kinds can result from improper surface preparation. For example, the plaster's ability to adhere to a surface will be compromised if dirt, dust, or other contaminants are left behind.

    In addition, plaster can dry unevenly on uneven or rough surfaces, leading to cracks and other defects.

    Plastering a surface requires first removing any dirt or debris that might get in the way.

    Wire brushes, scrapers, vacuum cleaners, and cans of compressed air are all useful tools for this task. Next, use a detergent or degreaser to clean the surface thoroughly and get rid of any lingering contaminants.

    A base coat of plaster may be required to achieve a smooth finish if the surface is very rough or uneven. The final coat of plaster will adhere better and dry more uniformly if you do this. In addition, plaster and its supporting surface may need to be bonded with a bonding agent in some situations.

    Poor Quality Materials

    In plastering, the end product is highly dependent on the materials' quality. Defects like delamination, cracking, and uneven drying can result from low-quality materials.

    Using low-quality plaster is a common contributor to imperfections in plasterwork. Poorly mixed or otherwise subpar plaster can fall into this category. Poor quality plaster can cause a number of issues, including a lack of durability and an uneven drying time.

    Inadequate Mixing Ratios

    Plastering defects can also be caused by using the wrong mixing ratios. As a result, plaster can dry unevenly or fail to adhere to the surface if not mixed properly, leading to cracks and other imperfections.

    Over or under-watering the plaster is a common mixing error.

    Too much water may cause the plaster to become too thin, making it difficult to apply. When applying plaster, it's important to strike a balance between adding too much water and making the mixture too thick and difficult to spread, which can result in an uneven finish.

    Plaster defects can be avoided by strictly adhering to the manufacturer's recommended mixing ratios. This may require exact measurements, the right equipment, and sufficient time spent mixing the plaster.

    Inadequate Curing Time

    Plastering defects are often the result of improper curing time.

    Curing time is the amount of time required for the plaster to dry and harden completely.

    Plaster can have a variety of issues if it is not given enough time to cure, including poor adhesion to the surface and uneven drying.

    Different types of plaster and environmental conditions like temperature and humidity affect the amount of time needed for the plaster to cure. When curing times are inadequate, problems like cracking, delamination, and an uneven finish can occur.

    When applying plaster, wait the recommended amount of time for curing. The time needed for the plaster to dry before painting or applying other finishes may need to be considered, as well as the time needed between coats.

    How Can Plaster Defects Be Avoided During The Construction Phase?

    During the building process, there are a number of things that can be done to avoid plaster defects. Some advice on how to avoid these flaws follows:

    Proper Mixing Of Materials

    Plaster faults are commonly brought on by a need for more attention to detail during the mixing process. Therefore, adhering to the manufacturer's instructions is crucial when mixing plaster. This means using the right amount of water, thoroughly mixing the materials, and employing the right mixing tools for plaster.

    Humidity And Temperature Control

    Plaster defects can be avoided with proper management of temperature and humidity. Adhesion, cracking, and discolouration problems arise from extreme heat or humidity. Therefore, plastering should be done in an environment with constant temperature and humidity. Tools for controlling temperature and humidity can help with this.

    Techniques For Proper Application

    Plaster defects can be avoided with careful application. Plaster must be applied in thin, even coats to protect the entire surface. Over-troweling, which can lead to cracking and blistering, should also be avoided.

    Environmental Factors

    Plaster flaws can also be caused by weather conditions like too much or too little moisture in the air. In order for the plaster to dry properly, the room's temperature and humidity must be within its ideal range. A dehumidifier or other form of ventilation can help with this.

    Examining The Substrate

    Inspecting the substrate for cleanliness, dryness, and the absence of defects or debris before applying plaster is important. The plaster will have imperfections if there are flaws or debris on the substrate.

    Using High-Quality Materials

    Plaster defects can also be avoided by using high-quality materials. A suitable plaster that is suitable for the substrate should be selected, and supplies should be purchased from a reliable source.

    Use Of Safety Equipment

    Plaster defects can be avoided with the right safety gear. First, wear protective gear like gloves, goggles, and a face mask. Dust and chemicals from plastering materials can be dangerous if breathed in or come into touch with the skin.


    worker plastering gypsum board wall

    Careful handling of the plastering process is key to preventing frequent problems in building construction.

    These problems might be as modest as a few cracks or as major as the entire structure collapsing.

    Plastering problems include cracks, loose plaster, flaking plaster, bubbling and blistering plaster, efflorescence, grinning and uneven finishes, popping and cracking plaster, expansion and debonding plaster, and a lack of a smooth, even surface.

    Plaster cracks can appear for a variety of reasons, including shifts in humidity or temperature, uneven surfaces, structural issues in the building, sloppy craftsmanship, or extreme shrinkage. Hollow plaster, sloppy installation, or overwatering are all potential causes of cracking. Bricks and other materials frequently show fractures where their joints have separated.

    Plaster flaking happens when a plastered surface develops microscopic, loose particles, usually as a result of broken bonding between coatings of plaster.

    Patching is necessary when peeling plaster occurs on the surface. It is possible to reduce adhesion discrepancies with careful material and surface treatment selection.

    Plaster can cause blooding and scorching if placed on a damp surface or if overused.

    To prevent these problems, make sure the surface is dry before plastering, and use thin coats of plaster. Dry brushing and cleaning the affected area several times can reduce efflorescence.

    Inadequate curing and incorrect mixing cause loose plaster, while the loss of mortar joints causes grinning due to a change in suction. An incorrect application or lack of sufficient preparation might lead to an uneven finish.

    Conical holes, or "popping," appear in the plaster as it cracks, usually as a result of foreign particles in the mortar. Changing out the plaster can fix expansion-related issues like layer cracking, spalling, swelling, and softening.

    Debonding of plaster, too much suction from undercoats, too thin of a finishing layer, and salts that melt when heated are all potential causes of a soft plastered surface.

    Fixing these typical plastering issues will help property owners get a finished plaster job that looks great and lasts for years.

    Inadequate surface preparation, low-quality materials, improper mixing ratios, and insufficient drying time are just a few of the causes of faults in plastering.

    Using a cleanser or degreaser to clean the surface and then applying a base coat for a smooth finish are all examples of good surface preparation.

    Inadequate mixing ratios can produce uneven drying and poor adhesion, and low-quality materials can cause delamination and cracking.

    Plastering flaws can also result from not allowing enough time for cure. Mixing plaster properly requires precise measures, the appropriate tools, and enough time to allow for the ingredients to fully incorporate. Plaster drying times vary depending on the type of plaster used and environmental factors, leading to issues including cracking, delamination, and uneven finishes.

    Content Summary

    • Plastering imperfections can occur despite careful attention to detail.
    • Common plastering defects range from hairline cracks to collapse.
    • Factors contributing to defects include poor plaster mixing, application methods, and exposure to elements.
    • Proper surface preparation, high-quality materials, and curing time are crucial for preventing defects.
    • Cracks in plastering can vary in size and result from temperature changes, structural flaws, and more.
    • Crazing appears as a web-like pattern of tiny cracks due to water absorption or poor application.
    • Cracks with hollowness can be caused by poor workmanship or excessive water in the plaster mixture.
    • Joint separation cracks occur where different materials meet due to thermal movement.
    • Falling out of plaster can lead to flaking or peeling, caused by broken bonds between layers.
    • Flaking occurs when a plastered surface develops loose particles.
    • Peeling happens when surface plaster breaks off, resulting in patches.
    • Bubbling and blistering occur when plaster is applied to a wet surface or overworked.
    • Dry the surface thoroughly and apply plaster in thin layers to avoid bubbling and blistering.
    • Efflorescence is caused by soluble salts in plaster ingredients and construction materials.
    • Efflorescence appears as a white crystalline substance and can be mitigated by dry-brushing and washing.
    • Loose plaster results from displacement due to external forces, inadequate curing, or improper mixing.
    • Grinning occurs when mortar joints are visible through the plaster and can be covered with an undercoat.
    • The uneven finish can be prevented by proper surface preparation and applying plaster evenly.
    • Sand the uneven finish and apply another thin layer of plaster to achieve a smooth result.
    • Popping of plastering is the formation of conical holes caused by contamination particles in the mixture.
    • Avoid plaster popping by ensuring the mortar mixture is free of foreign particles.
    • Expansion leads to layer cracking, spalling, and softening, often caused by gypsum and water reaction.
    • The softness of plaster occurs due to excessive wetness in specific spots and various causes.
    • Plaster debonding refers to the plaster coming loose from the wall caused by thick coatings or improper preparation.
    • Remove dirt, grease, and prepare the substrate properly to prevent plaster debonding.
    • Rust stains on plastered surfaces are caused by metal objects, water damage, or high humidity levels.
    • Inadequate surface preparation compromises plaster adhesion and can lead to cracks.
    • Low-quality materials contribute to defects such as delamination and uneven drying.
    • Improper mixing ratios can result in uneven drying and poor adhesion.
    • Strictly adhere to the manufacturer's recommended mixing ratios to avoid plastering defects.
    • Inadequate curing time can lead to poor adhesion, cracking, and an uneven finish.
    • Consider recommended curing time and drying between coats for a successful plastering process.
    • Proper mixing of materials is crucial to avoid plaster faults.
    • Adhere to the manufacturer's instructions for water amount, thorough mixing, and proper tools.
    • Temperature and humidity control help prevent adhesion and cracking problems.
    • Apply plaster in thin, even coats and avoid over-troweling to prevent defects.
    • Environmental factors like moisture affect plaster drying and should be controlled.
    • Inspect the substrate for cleanliness, dryness, and absence of defects before plastering.
    • High-quality materials and reliable sources ensure better plastering results.
    • Use safety equipment like gloves, goggles, and a face mask to protect against plastering materials.
    • Plaster defects can range from minor cosmetic issues to structural concerns.

    It would help if you waited 2-4 weeks before painting over the new plaster. This allows the plaster to fully dry and cure, essential for ensuring that the paint adheres properly and does not peel or flake over time. However, it is important to follow the manufacturer's instructions for the specific type of plaster used, as curing time can vary depending on factors such as temperature and humidity. In addition, rushing the process can lead to significant issues and may require the entire plastering job to be redone.

    No, it is not necessary to use a primer before plastering. However, using a primer can help to improve adhesion and create a more even surface for the plaster to adhere to. Additionally, a primer can help to seal the surface and prevent moisture from seeping into the plaster, which can cause it to deteriorate over time. Ultimately, whether or not to use a primer before plastering depends on the specific project and the condition of the plastered surface.

    Yes, you can use drywall mud instead of plaster for certain projects. Drywall mud is a common alternative to plaster for creating a smooth finish on walls and ceilings. It is easy to apply, dries quickly, and can be sanded and painted. However, it is important to note that drywall mud is not as durable as plaster and may not be suitable for high-traffic areas or areas prone to moisture. Additionally, drywall mud may not be able to cover larger imperfections as effectively as plaster. Ultimately, the decision to use drywall mud or plaster will depend on the project's specific needs.

    Yes, plaster defects can be fixed after construction. Several methods for repairing plaster defects include patching, filling, and smoothing. The method used will depend on the type and severity of the defect. Minor defects, such as cracks or small holes, can often be easily repaired using a patching compound or filler, while larger defects may require more extensive work, such as re-plastering or skim-coating. It is important to address plaster defects as soon as possible, as leaving them untreated can lead to further damage and may require more costly repairs in the future.

    If plaster defects are discovered during construction, they should be addressed as soon as possible. The first step is to identify the cause of the defect, whether it is due to poor surface preparation, incorrect mixing ratios, or other factors. Once the cause is identified, appropriate measures should be taken to fix the defect. This may involve reapplying the plaster, patching the defect, or using a skim-coating technique to smooth the surface. It is important to address the defect promptly to prevent it from worsening and causing further damage.

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