Repainting a room is one of the most accessible renovation tasks a homeowner can take on — but doing it properly in Czech residential buildings involves specific considerations. Older apartment blocks, whether brick-built or panel construction, have wall surfaces with different properties than newly plastered walls in modern houses. Choosing the wrong primer or skipping surface preparation entirely is the main reason paint starts peeling within months.

This guide covers the full process: assessing the existing wall, preparing the surface, selecting the right products, and applying paint in a way that holds up.

Assessing the Existing Surface

Before anything is applied, the wall needs to be examined. Run a dry hand across the surface. Powdery residue indicates chalky or disintegrating paint — common in panel flats built between 1960–1990, which were typically finished with water-based tempera or low-quality emulsions. These surfaces require a binding primer before any new coat.

Check for:

  • Cracks — hairline cracks in plaster are cosmetic; wider cracks (over 0.5 mm) may indicate movement and need filling with flexible filler
  • Moisture stains — yellowish or grey patches near ceilings or window reveals suggest water ingress; this must be resolved before painting
  • Efflorescence — white crystalline deposits on masonry-backed walls indicate salt migration; brush off and apply a sealing primer
  • Grease or smoke staining — kitchens and areas near fireplaces need degreasing and a stain-blocking primer

Note on panel buildings: Many panelák walls are finished directly on the concrete panel with a thin skim coat. Sanding aggressively can break through to bare concrete. Use fine-grit paper (180–220) and limit preparation to smoothing raised areas, not stripping the surface.

Filling Cracks and Surface Preparation

Small defects should be filled before priming. For hairline cracks, a ready-mixed filler applied with a flexible spatula works well. Common products in Czech hardware stores include KNAUF Multifinish and Baumit UniversalSpachtel. Larger cracks should be widened slightly with a scraper (to create a mechanical key), filled in layers not exceeding 5 mm, and sanded after each coat dries.

Sanding the entire wall is not always necessary, but any paint ridges, brush marks or rough patches should be smoothed. Use 80–120 grit paper for rough surfaces, finishing with 150–180 grit. Remove all sanding dust with a damp cloth — dust left on the wall prevents primer from bonding.

Renovation supplies including fillers and primers
Common repair materials available at OBI, Bauhaus and Hornbach in the Czech Republic — Source: Wikimedia Commons (CC)

Primer Selection

The primer is more important than the topcoat. It determines adhesion, affects final sheen, and controls how much paint the wall absorbs.

Universal Primer

Suitable for most interior walls that are in reasonable condition. Penetrates the surface and consolidates loose material. CERESIT CT 17 Universal Primer, PRIMALEX Penetrace, and Knauf Tiefengrund are widely available and work on plaster, gypsum board, concrete and old emulsion.

Binding/Fixative Primer

For chalky walls that absorb water rapidly or crumble when wet, a binder primer must be used. These primers contain synthetic resins that consolidate the surface. Balakom by PPG and PRIMALEX Podlak Extreme are designed specifically for this. Apply one coat, wait until fully dry (typically 4–6 hours at 20°C), then test the surface again.

Stain-Blocking Primer

Nicotine staining, water marks and smoke damage bleed through standard primers within weeks. Use a shellac-based or solvent-based stain block — Kilz Original or Zinsser BIN are available through specialist suppliers in the Czech Republic — before switching back to water-based products.

Choosing Interior Paint

The Czech market is dominated by latex (disperzní barvy) — water-based emulsion paints suitable for most interior applications. These are the correct default choice for walls and ceilings in living spaces, bedrooms, corridors and stairwells.

  • Primalex Plus — the most widely sold interior white in the Czech Republic. Suitable as a base for most rooms. Good coverage at approximately 10–12 m² per litre. Tinted versions available through OBI and Bauhaus colour-mixing systems
  • Dulux EasyCare — washable matt finish, appropriate for kitchens, children's rooms and corridors where walls are touched frequently
  • Primalex Inspiro — slightly higher pigment load than Primalex Plus; better for covering darker colours without excessive coats
  • Balakom Ceramic — contains ceramic particles for improved scrub resistance; more durable but harder to apply evenly for beginners

Sheen levels: Matt finishes hide surface irregularities best but cannot be wiped. Eggshell and satin finishes are more practical for kitchens and bathrooms. Avoid high-gloss latex on walls — it emphasises every imperfection and is difficult to recoat without full sanding.

Tools and Equipment

Using the correct tools reduces the number of coats needed and improves the final result significantly.

  • 230 mm or 270 mm roller with medium nap (10–12 mm) for smooth to semi-rough plaster
  • 50 mm synthetic bristle brush for cutting in at edges, corners and around woodwork
  • Paint tray with roller grid — not a bucket, which overloads the roller
  • Painter's tape (malířská páska) — 2–3 days maximum adhesion type; remove before the paint fully cures
  • Drop cloths for floors and furniture
  • Extension pole for the roller — essential for ceilings and reduces back strain
Power drill — one of the core DIY tools for home renovation
A cordless drill is useful during wall preparation for removing fixtures and anchor bolts — Source: Wikimedia Commons (CC)

Application Process

  1. Apply primer to the entire wall surface; work from top to bottom, maintaining a wet edge. Allow to dry fully — do not rush
  2. Cut in along all edges (ceiling line, skirting, window reveals, door frames) with the brush before using the roller on the main field
  3. Apply the first coat with the roller using a W or M pattern across the wall, then lightly backroll in one direction without reloading the roller
  4. Allow the first coat to dry for at least 4 hours at 20°C and 60% relative humidity. In Czech winter conditions with dry heated air, drying may take less time — but do not apply the second coat until touch-dry throughout
  5. Apply the second coat in the opposite direction to the first. This cross-hatch technique fills in any gaps and produces more even coverage
  6. In most cases, two coats over primer are sufficient for white or light colours. Vivid or dark colours may require three coats

Working Conditions

Paint should not be applied in temperatures below 10°C or above 30°C. Czech building interiors are typically heated in winter, but freshly opened apartments after building work can be cold. Always ensure the room is at working temperature for at least 24 hours before painting.

Ventilate during drying, but avoid direct draughts which can cause uneven drying. Close windows at night — cold air raises humidity and slows drying significantly.

Common Mistakes

  • Skipping primer on a freshly plastered wall — new gypsum plaster is highly absorbent and will consume multiple coats of topcoat without penetrating primer
  • Painting over mould with standard emulsion — mould must be treated with fungicidal solution (e.g. SAVO Antiplíseň) and the source of moisture resolved
  • Using cheap brushes that shed bristles — embedded bristles in dried paint require sanding and recoating
  • Overloading the roller — this causes spattering and thick uneven films that take longer to dry and may crack
  • Removing painter's tape too late — if tape is left until the paint fully cures, it can pull up the paint film with it

For reference on paint composition and standards, the European standard ISO 11998 covers scrub resistance testing, and the Czech technical standard ČSN EN 1062-1 classifies exterior and interior coating systems.