Damp on walls is one of the most common problems faced by homeowners in Greece. It appears in both new and old buildings, in flats and detached houses, and if it is not tackled at its root, it comes back again and again, no matter how many times you repaint.
The problem is not only cosmetic. Damp destroys plaster, corrodes the steel reinforcement, degrades the building's energy performance and creates ideal conditions for mould, which directly affects the health of the occupants.
The solution is not repainting. It is identifying the cause and dealing with it permanently.
Damp is defined as the unwanted presence of water or water vapour in the structure of a building. It appears in various forms: damp patches on the wall, peeling paint and plaster, blistering, white salt deposits (efflorescence) and, of course, mould.
The acceptable humidity level indoors ranges from 40% to 60%. Above that, conditions are created for mould growth and the gradual deterioration of building materials. Read more about mould on walls and ceilings and the health risks it poses.
How damp is treated depends entirely on its type. A wrong diagnosis means the wrong solution and a recurrence of the problem.
Where it appears: basements, ground floors, walls in contact with the ground.
Water is absorbed from the ground through the pores of the masonry and rises up the wall. This is damp in the wall coming from the ground, one of the most common types in old buildings without a damp-proof barrier at the base. It typically appears low on the wall, usually up to a height of 0.70 m, and is often accompanied by salt deposits (efflorescence: white traces of salt on the surface). In coastal or riverside areas the problem is more severe because of the high moisture content of the soil.
Where it appears: external walls, columns, room corners, north-facing elevations.
It comes from rain penetrating the external walls, from cracks in the plaster or from inadequate external waterproofing. It is also linked to thermal bridges: when parts of the wall (columns, beams) have no thermal insulation, their inner surface stays cold and the moisture in the air condenses on them.
Where it appears: top-floor ceilings, the upper part of walls, around gutters and downpipes.
It comes from inadequate or damaged roof waterproofing, from cracks, damaged gutters or joints. The water comes down from above and appears on the ceiling or the upper part of the walls.
Before any intervention, identifying the cause is essential:
The most reliable way to identify it is a thermographic inspection with a special thermal camera that captures cold spots, thermal bridges and hidden leaks that cannot be seen with the naked eye.
For rising damp from the ground: Creating a horizontal barrier at the base of the wall with special cementitious waterproofing or resin-based materials. In severe cases a drainage membrane (dimpled membrane) is needed to carry water away from the base. Ordinary waterproof paints do not solve this type of damp.
For lateral penetration from thermal bridges: The only definitive solution is thermal insulation. If the walls have no thermal insulation, the columns and beams stay cold and the moisture in the indoor air condenses on them. External thermal insulation (external wall insulation, ETICS) eliminates thermal bridges completely. Where it is not feasible, interior thermal insulation with mineral wool is an effective alternative.
For lateral penetration from rain: External waterproofing of the wall with special liquid-applied materials or water repellents. In older homes it is often combined with external wall insulation for double protection.
For damp from the roof: The only solution is roof waterproofing. Depending on the condition of the roof and the substrate, the choice is:
There is no solution for damp on the walls of a top floor without waterproofing the roof at the same time. Any other approach is temporary.
For a complete picture of the methods of protection against water, read what waterproofing is and why your building needs it.
Many people deal with damp by repainting or using waterproof paints. This approach almost always fails because it treats the symptom, not the cause. The damp comes back, usually worse. You need a more substantial intervention when:
Damp on walls is not only a cosmetic or structural problem. Wet building materials conduct heat much better than dry ones, which means that a damp wall loses significantly more heat in winter. This directly increases the heating bill and lowers the building's energy class.
Conversely, buildings with proper thermal insulation and waterproofing do not suffer from damp caused by thermal bridges and maintain higher energy performance.
Damp on walls needs an on-site assessment for a correct diagnosis. With 25+ years of experience in building insulation and waterproofing in Attica, Goumas Insulation identifies the cause and applies the permanent solution.
Damp does not always come from rain. It can be caused by thermal bridges (condensation of water vapour on cold surfaces), by rising damp from the ground or by a hidden pipe leak. A thermographic inspection pinpoints the cause accurately.
No. Waterproof paints may temporarily cover the symptoms, but they do not deal with the cause. The damp comes back, usually more intensely. A permanent solution requires identifying the cause and an appropriate intervention.
First the damaged plaster and paint are removed, and the surface is cleaned and dried completely. Then the appropriate waterproofing and repair are carried out. Simply cleaning without dealing with the cause does not give a permanent result.
Yes. Apart from structural deterioration, damp creates conditions for mould, which causes respiratory problems, coughing, asthma and infections. Children, the elderly and people with respiratory problems are particularly vulnerable.
With roof waterproofing. There is no other permanent solution. The choice of method depends on the condition of the roof and is made after an on-site inspection.
Damp is the cause; mould is one of the symptoms. Without damp there is no mould. Cleaning mould without dealing with the damp is only temporary.
It is damp in the wall that comes from the ground. Water is absorbed through the pores of the masonry and rises up the wall, appearing low down with salt deposits. It is particularly common in buildings built before 1980 that have no damp-proof barrier at the base.
Tags
Certified Insulation
Click on the pictures and see our credentials.
