Capillary rise
Moisture rising from the ground through porous materials. Appears in lower areas - ground floors, basements, wall bases.
How Does Moisture Affect Paint?
The hidden cause behind most paint failures
Why moisture is paint's number-one enemy
Moisture is the single most important factor affecting paint durability on apartment buildings. It may not be visible on the day of application, but it almost always reveals itself within the first few years.
Paint doesn't fail because it "wasn't good enough". It fails because the substrate wasn't stable and dry. If there's water beneath the film, no paint will hold.
What happens when moisture is present
Moisture can reside inside the plaster, behind cracks, or beneath old paint layers. When the surface is exposed to sunlight, moisture turns to vapour, creating pressure beneath the film.
If the system doesn't allow breathability, the result is threefold: blistering, delamination, and peeling. Three failures that all start from the same cause.
Four moisture sources in apartment buildings
Moisture doesn't just "appear". It always comes from somewhere. Identifying the source is the first step to any proper solution.
Waterproofing failure
Water entering through rooftops, terraces, deteriorated membranes. Damage appears inside or at exterior corners.
Cracks and microcracks
Rainwater entering through plaster cracks or diagonal cracks near windows. Even hairline cracks are enough.
Condensation
In interior spaces with inadequate ventilation - kitchens, bathrooms, closed rooms. Vapour condenses on cold walls.
Breathability vs waterproofing: the critical balance
Waterproofing prevents water ingress. Breathability allows vapour to escape. These are not opposites - the right system does both: blocks rain but lets vapour escape.
The Sd value (equivalent air thickness) measures how well a film "breathes". Low Sd = high breathability. High Sd = sealed "lid". The wrong choice traps moisture - and the paint is lost within months.
The wrong choice can trap moisture inside the wall - making things worse than before.
Four checks before opening a tin
Paint must not be applied on a substrate with high moisture content. Four simple checks prevent months of failure.
Efflorescence
Visual check for white crystalline deposits on the surface. If efflorescence is present, moisture is present - don't paint.
Moisture reading
With a digital moisture meter. Readings above 4–5% mean the wall still needs time to dry.
Crack inspection
Every crack - even hairline - can let water in. Identify and seal before painting.
Roof waterproofing
Check the condition of insulation and waterproofing. If the roof leaks, there's no point painting the facade.
Proper prevention: the sequence matters
Moisture cannot be hidden with more paint. Proper treatment always starts with diagnosis - and follows a specific sequence.
① Diagnose
Identify the moisture source. Capillary? Waterproofing? Cracks? Without proper diagnosis, every fix is guesswork.
② Repair
Restore waterproofing, seal cracks, fix plaster. Paint cannot solve structural problems.
③ Dry
The wall must dry completely. New plaster needs 28+ days of curing. Rushing = failure.
④ Right system
Choose a paint system with an appropriate Sd value - breathable yet waterproof. Primer + topcoat at the correct thickness.
The correct sequence is always: diagnose → repair → dry → paint. Never the other way around.
Related Articles
Why Does Paint Peel? What Causes Paint Blistering? Capillary Rise & Moisture Transport Sd Value & Breathability
Paints for Building Facades
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