Plastering on OSB boards on the facade of a building

Oriented Strand Board (OSB) plastering can be challenging, particularly when it’s done on a building’s exterior. In contrast to conventional surfaces like concrete or brick, OSB presents unique difficulties. But, you can achieve a beautiful and long-lasting finish that improves the look and longevity of your building with the appropriate method.

Because of their structural strength and affordability, OSB boards are widely used in construction. But because of their smooth surface and propensity to absorb moisture, they need to be specially prepared before plastering. The secret to success is utilizing the right materials, properly priming the surface, and applying the plastering techniques.

We’ll take you through each of the crucial steps in this guide to plastering OSB boards for a facade. You’ll discover how to properly prepare the surface, select the best bonding agents, and apply plaster. You can build a facade that is long-lasting, weather-resistant, and beautiful with meticulous attention to detail.

Is it possible to plaster OSB

Homeowners carefully consider their finishing options after deciding to use OSB for the exterior of their home or chipboards for interior construction. Simultaneously, the question of whether OSB boards can be plastered usually comes up first. After all, even wood coated in water-repellent compounds will absorb moisture if the aesthetics are neglected and the OSB is left exposed to the elements (particularly on the facade).

The board can swell in the summer and defrost in the winter with this much water. OSB will become weaker, darken, and distort. Furthermore, the chemical nature of the binder in OSB presents a significant drawback, which is why the boards must be shielded from temperatures higher than +30 ° C. Thus, the builders considered the protective coating for the plates from the beginning of their release.

The following finishes are most frequently used:

• painting (the cheapest and simplest option);
• Pumping with wallpaper (suitable only in rooms);
• cladding fastened directly on the stoves with decorative panels (a fairly expensive way that does not solve all problems to preserve the OSP);
• Covering with siding (does not eliminate the problems of the combustibility of plates, requires additional measures for vapor barrier of the OSS);
• tiles cladding (suitable for premises, but “overlaps oxygen” of wood);
• cladding of plates with a coating of decorative stone (the most expensive and laborious way);
• plastering.

The following characteristics should be present in the OSB protective coating:

• water resistance and water resistance;
• sufficient mechanical strength;
• temperature stability (withstand sharp jumps);
• vapor permeability;
• environmental friendliness;
• fire safety;
• long service life;
• repairability;
• unattractiveness to mold, mildew and rodents;
• resistance to solar radiation;
• light weight;
• affordable price;
• easy operation without unnecessary costs;
• ability to do it yourself.

Why OSB panels need to be plastered

The qualities listed above apply to plaster.

Additionally, plaster coating

• serves as additional heat and sound insulation;
• forms a monolithic coating that hides seams and surface defects;
• can give the building a unique look.

As a result, plaster is frequently used by private owners to decorate interior spaces and coat OSB boards on the facade.

Once the chipboards are properly plastered, they tend to forget about repairs for a very long time. It is also easily changeable by painting it in different colors if you grow tired of the way it looks. Such a coating prevents drafts, is dependable, and is simple to clean.

What kind of plaster is used for OSB boards

Generally speaking, choosing the composition of plaster doesn’t present any especially challenging issues if plaster is the last component of the "layer cake," which is a composite OSB coating. So, when we talk about plasters, we’ll talk about traditional compositions made with different binders. Furthermore, compositions specifically made for OSB plastering exist.

Types of plaster mixtures include:

• leveling (rough);
• decorative (finishing);
• special (heat-insulating, X-ray protective, noise-reducing, waterproofing, etc.)

By application area, plaster mixtures are separated into:

• internal (for use only in heated rooms);
• external (used for facades, as well as indoors);
• universal.

The foundation of any composition consists of binders, filler (natural or synthetic particles that make up the majority of the volume), and a few useful additives.

Mineral

Mineral binders are natural materials like cement, gypsum, clay, and lime.

• strength;
• water resistance;
• vapor permeability;
• frost resistance;
• environmental friendliness;
• non-flammability;
• biostability;
• resistance to UV rays;
• maintainability;
• cheapness;
• durability.

• inelastic (cannot withstand vibrations).

Traditional gypsum mixtures are the least appropriate of these compositions for street work.

Elastic

Ready-made mixture with acrylic resins serving as its binding ingredient. Elastic plaster’s capacity to stretch under load is its primary benefit. As such, it is appropriate for covering the walls of newly constructed homes and buildings in seismically active areas.

• waterproof;
• strength;
• vapor permeability;
• environmental friendliness;
• rich palette;
• durability;
• maintainability;
• high adhesiveness;
• plasticity, ease of application;
• easy to care for.

• not resistant to fire;
• low vapor permeability;
• low resistance to UV rays;
• can accumulate static and attract dust

More costly than those made of minerals. Frequently categorized as polymers, such as silicone plaster mixtures. Applications that are universal.

Superelastic compositions are the priciest ready-made mixes and are categorized as silicone compositions. Not particularly disadvantageous (apart from the cost). Form a film that is extremely challenging to remove and break through. very robust and persistent.

Polymer

• silicone (vapor-permeable, waterproof);
• siloxane (water resistance lasts only 3-5 years);
• acrylic;
• polymer cement (filler – polymer fibers);
• and others.

Polymers are components that bind.

Two categories of bases:

• water-soluble;
• soluble in organic solvents.

The cost of compositions is greater than that of mineral mixes.

Decorative

Specially prepared blends for ornamental applications.

For facades and interior spaces, the following kinds of mixtures are created:

• textured;
• structural;
• pebble (mosaic and marble plasters);
• flock;
• colored;
• Venetian.

The filler type or layer processing techniques produce the decorative effect.

Methods for plastering OSB boards

The following issues could arise during the plaster layer application:

• absorption of moisture from the solution by wood;
• the formation of cracks in the plaster coating due to the “play” of wood when moistened;
• difficulties in ensuring reliable adhesion.

Numerous approaches are used to solve these issues. Plastering OSB can be done in two primary ways:

• without insulation;
• with insulation.

OSB boards need to be securely fastened to the wall in both situations to avoid noticeable movement while working and when shrinking.

Traditional way

As an extreme measure that is best avoided, information on plastering oriented strand sheet material without insulation is provided. When it comes to operation, a property owner may face numerous difficulties if the plaster coating is not insulated.

To plaster, you will require:

• vapor-permeable membrane material, for example, Tyvek StuccoWap;
• stretched-cut mesh for reinforcement;
• adhesive composition;
• plaster mix.

1. A membrane sheet is attached to the OSB surface with a stapler. The sheets are joined with an overlap (10 cm) using glue or double-sided tape.
2. A reinforcing mesh is placed on top, attaching it to the OSB.
3. Apply a layer of adhesive composition (for complete immersion of the mesh in the composition, two layers must be applied).
4. A primer is applied to the dried glue to increase adhesion (better deep penetration).
5. Plaster the dried surface.

Using an elastic plaster composition from a reliable manufacturer is especially crucial for this method as it prevents the plaster layer from cracking due to the wood surface’s "movements." Cracks most frequently appear at the OSB joints. You can use bitumen cardboard, kraft paper, or roofing felt in place of a membrane.

Plastering OSB underneath putty is an additional method of protection. Putty and plaster mortar are comparable, but the filler in putty is much finer (stone flour, in actuality). The chip surface is primed, sanded, and dust-free before puttying. Any primer will work, but water-free wood compositions are ideal. After the primer is applied, the boards won’t absorb moisture from it.

Two roller applications of the primer mixture are made, drying between layers. Using a stapler and putty, a reinforcing mesh is fastened to the OSB surface following the primer application and drying process. The putty should contain the mesh. The chip surfaces are plastered with elastic, vapor-permeable, decorative compositions after the putty dries.

The ends of OSB are the areas most susceptible to moisture intrusion. It is necessary to prime them completely before attaching the sheets.

Insulation and plastering

Typically, insulation is completed outside the structure. For instance, 40 mm thick foam sheets are used as insulation when plastering OSB boards.

1. Insulation sheets are glued to the prepared OSB surface. After the glue has dried, the sheets are fixed with mushroom dowels, sinking the caps into the foam. The joints between the foam sheets are foamed, the foam protruding above the surface is cut off.
2. Apply the adhesive composition in a 3 mm layer, apply the mesh, straighten, smooth with a wide spatula, immersing the mesh sheet in the solution. The solution protruding above the mesh is leveled.
3. After the adhesive solution has dried, apply the prepared plaster mixture.

Plaster mixture application

The process is similar to the Wet Facade method. As a result, the related article offers insight into the subtleties of execution.

Use of plasterboard

Dry plasters include gypsum plasterboard sheets (GKL). Plasterboard plus OSB combined can significantly reduce noise compared to individual OSB and does not catch fire. Inside the room, OSB can be directly attached to gypsum plasterboard (without a guide frame). In this instance, self-tapping screws are used to secure OSB to the guides. Self-tapping screws are used to secure GKL to the same guides through OSB.

However, OSB and GKL joints shouldn’t line up. It is even possible to glue gypsum plasterboard to OSB and then secure it with self-tapping screws. GKL sheets are plastered and puttied nicely. Plastering can be done with almost any kind of plaster mix. In dry rooms, attaching a vapor barrier beneath the GKL is not required.

Features of plastering indoors and on the facade of the building

Furthermore, the materials and methods of plastering OSB boards differ when done indoors versus outside under different working conditions. A few days of dry, windless, and warm weather are selected for plastering facades. A canopy protects the workspace from the sun and unforeseen rain. The ambient temperature ought to be higher than +5, but not surpass +35 °C.

Inside, the atmosphere is more comfortable. Here, humidity (no more than 65%) and the lack of drafts are crucial. Plaster solutions cannot be dried more quickly by using fans or heaters. Cracks will result from conditions being broken. Turn off the electricity to the wiring before plastering.

Although plastering over OSB boards for a building facade can be difficult, the proper planning and supplies guarantee a smooth, long-lasting finish that resists weather and wear. In order to keep the facade’s integrity and appearance over time, proper priming, sealing, and plaster application are essential to preventing moisture damage and cracking.

Tool

Essentially, the same equipment is utilized as for other kinds of plastering:

• spatulas (with a metal working part);
• trowel;
• grater for grinding (with sandpaper);
• level;
• containers;
• short-haired roller;
• mixer;
• brush;
• masking tape;
• rags.

Preparing the OSB surface

OSB boards may have dirt and dust on them. Sanding the surface and removing dust and dirt stains are essential. Wood materials cannot be cleaned; instead, specialized cleaning solutions containing organic solvents, like white spirit, are utilized. The seams are puttied, primed, and sealed (elastic sealant is used for OSB since the board needs a side gap for adjustment). This creates a smooth surface.

Step	Description
Surface Preparation	Ensure OSB boards are clean, dry, and free of dust or grease.
Primer Application	Apply a suitable primer to enhance plaster adhesion.
Reinforcement	Attach fiberglass mesh to prevent cracking.
First Coat	Apply the first layer of plaster evenly over the surface.
Smoothing	Level the plaster and let it dry completely.
Final Coat	Add a second layer for a smooth, durable finish.
Drying	Allow the plaster to dry thoroughly before painting.

Plastering OSB boards on a building’s facade is a good way to achieve a smooth, long-lasting finish that improves the exterior’s look and durability. Plaster will adhere well and stay intact over time if the proper preparations are followed, such as sealing the OSB surface and using an appropriate mesh.

Using the right kind of plaster and layering it on will help you get a durable, uniform finish. Throughout the process, it’s crucial to exercise patience and give each layer enough time to dry completely before applying the next. Taking this cautious approach will stop common problems like peeling or cracking.

Plastering over OSB boards on a building’s facade can offer a durable and appealing solution if the proper materials and methods are used. Whether you’re building something from scratch or remodeling an old building, this technique can improve your project’s visual appeal and weather resistance.

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