Exterior paint is the finishing layer that protects plaster from moisture, UV radiation, and temperature fluctuations while also defining the appearance of the building for years to come. A mistake at this stage can quickly result in cracks, peeling, or color fading as early as after the first winter. Let us look at what to consider when choosing paint and how to select the right formulation for a specific type of plaster.

Why the Type of Plaster Determines the Choice of Paint

Exterior paint should be vapor-permeable and compatible with the substrate — otherwise, the coating may quickly crack or begin to peel. Different types of plaster require different paint formulations:

• mineral plaster — works well with silicate and mineral paints because these materials have similar vapor permeability;
• acrylic plaster — is usually painted with acrylic paint from the same manufacturer to avoid incompatibility between binding components;
• silicone plaster — requires silicone paints with similar elastic properties;
• decorative and textured plaster — requires preserving the surface texture, so preference is generally given to formulations that do not create an excessively dense film.

Using paint with lower vapor permeability than the plaster is not recommended: moisture that cannot escape outward may accumulate beneath the coating and gradually damage the finishing layer from within. Suitable plaster and compatible materials can be selected in the ITUM facade materials section, which offers products designed for different types of substrates.

Types of Exterior Paint: A Brief Overview

Before purchasing, it is worth understanding the main types of exterior paint available on the market.

1. Silicate paints — based on liquid glass, they offer high vapor permeability and durability and are well suited to mineral plaster.
2. Silicone paints — flexible, water-repellent, resistant to dirt, and capable of withstanding temperature fluctuations.
3. Acrylic paints — affordable and easy to apply, but generally have lower vapor permeability than silicate and silicone formulations.
4. Mineral (lime) paints — environmentally friendly and naturally antiseptic, although less resistant to mechanical impact.
5. Silicate-silicone (hybrid) paints — combine the vapor permeability of silicate formulations with the flexibility of silicone paints and are often used as a balanced solution.

How to Choose Exterior Paint: Key Criteria

When choosing exterior paint, it is important to consider not only the color but also the technical properties of the product.

Vapor permeability. The higher this value, the better the wall can release moisture, reducing the risk of condensation forming beneath the coating.

Water-repellent properties. High-quality paint should repel water from the surface and prevent it from penetrating the plaster structure.

UV resistance. This determines whether the facade will retain its rich color after several years of exposure to sunlight.

Coating elasticity. This is especially important in regions with significant temperature fluctuations — a flexible coating can accommodate minor movements of the substrate without cracking.

Resistance to dirt and biological growth. Formulations containing antiseptic additives help protect the facade from mold, fungi, and moss, particularly in shaded and damp areas.

Coverage and consumption. These affect the overall cost of the project — if the paint has poor coverage, more coats will be required, increasing material consumption.

Preparing Plaster Before Painting

The quality of the final coating directly depends on proper substrate preparation. The process usually includes several stages:

Allow the plaster to dry completely — the minimum drying time depends on the type of material and layer thickness and usually ranges from several days to 2–4 weeks.

Clean the surface of dust, efflorescence, and other contaminants.

Prime the substrate with a primer compatible with both the type of plaster and the selected paint — this improves adhesion and reduces paint consumption.

If cracks or chips are present, repair the defects with suitable repair compounds before applying paint.

Check the moisture level of the substrate before starting painting work, especially during colder periods of the year.

Materials for preparing and repairing the substrate before painting can be found in the ITUM repair materials section — this makes it easier to select compatible products as part of a single purchase.

Common Mistakes When Choosing and Applying Exterior Paint

To avoid facade problems during the very first season, it is important to consider common mistakes: applying paint to plaster that has not fully dried or has not been properly primed; using a low-vapor-permeability formulation on mineral plaster; painting in very hot weather or under direct sunlight, which can cause the coating to form unevenly; skipping the second coat — a single coat often results in uneven color and reduced durability; and ignoring antiseptic additives in regions with high humidity, which can eventually lead to mold growth.

Choosing the right exterior paint begins with identifying the type of plaster and its vapor-permeability requirements rather than selecting a shade from a color chart. To ensure that the facade maintains its appearance and protective properties for decades, it is important to use compatible materials at every stage — from plaster and primer to the final coating. Compatible products for a specific project can be selected from a supplier offering a complete range of facade materials — from plasters and paints to repair compounds and additives designed to improve the durability of the coating.