What rising damp actually is
Capillary action is the phenomenon by which water present in the ground climbs through the pores of a wall, much as a sponge draws water up from its base without being fully submerged. Unlike a localised leak, caused by a specific fracture or fault, rising damp is a slow and constant process that does not depend on any breakage at all — only on the moisture in the soil and the wall material's capacity to absorb and carry it upwards.
Why it is so frequent on coastal ground floors
Several factors particular to the Vega Baja and the Costa Blanca combine to make rising damp far more common here than inland.
High water table and proximity to the sea
In coastal municipalities the groundwater level tends to sit closer to the surface than inland, especially in areas near former wetlands or salt marshes. That means the foundations of many properties are in almost permanent contact with saturated ground.
Older construction with no adequate barrier
A good share of the housing stock built several decades ago has no effective damp-proof course in the foundations, a measure that is practically standard in current construction. Without that barrier the wall absorbs water from the ground continuously, from the day it was built.
High ambient humidity from the sea
Relative humidity in coastal areas is consistently higher than inland, which slows the natural evaporation of water that has already climbed the wall, keeping the damp visible for longer before it clears on its own.
Telling rising damp apart from other damp
- It always appears in the lower part of the wall, normally up to a height of between half a metre and a metre, and never higher.
- It usually comes with whitish mineral salt staining, known as efflorescence, left behind as the evaporating water dries.
- It bears no relation to any nearby pipework or to how the property is used: it appears the same whether the house is lived in or closed.
- It worsens in periods of more rain or a higher water table and improves slightly in summer, though it rarely disappears entirely without treatment.
If the staining appears higher up the wall, has a clear localised origin, or coincides with the run of a pipe, it is more likely an ordinary leak rather than rising damp — and the treatment required is entirely different.
The treatments that actually exist
Injection of water-repellent resins
This means drilling the wall at the appropriate height and injecting a resin that creates a chemical waterproof barrier within the material itself, stopping water climbing above that point. It is one of the most common treatments for its balance between effectiveness and the amount of work involved.
Wall ventilation systems
Small tubes or vents are fitted that encourage evaporation of the water held in the wall, accelerating the natural drying process without chemical drilling. It is usually combined with other treatments in more advanced cases, particularly where the wall is thick and resin alone will not fully stop the rise.
Breathable finishes
Once the source has been treated, specific renders and paints are applied that let the wall continue to breathe and release residual moisture, rather than sealing it completely with conventional paint, which would trap the moisture inside and cause it to reappear more strongly at a nearby point.
Why painting over the stain does not work
It is common, especially in rental properties between tenants, to try to cover the stain with a coat of paint before the next occupancy. The result is predictable: the damp keeps climbing the wall, conventional paint does not let the surface breathe, and the stain returns within weeks — sometimes worse than before, because the trapped water finds another way out nearby. Any serious treatment for rising damp starts by tackling the source, not by disguising the symptom.
What to check before deciding on a treatment
Before committing to any work, confirm the diagnosis is right. Checking whether the stain respects that characteristic half-metre to one-metre height, whether whitish salts appear to the touch, and whether the damp stays the same whether the property is occupied or closed helps rule out other causes — a leak from nearby buried pipework, or seepage from a poorly waterproofed terrace or roof above. Mistaking the source leads to a treatment that does not address the real cause, and the problem returns months later with the money already spent. An experienced professional will normally use a contact moisture meter, which gives an objective reading of the water content in the material, rather than relying on visual observation of the stain alone. A correct diagnosis, even if it takes a little longer than starting treatment straight away, almost always works out cheaper than repeating work that never tackled the real cause.
If you have damp staining low on a wall that will not disappear even after repainting, Manitas covers the whole Vega Baja and quotes free of charge to assess the right treatment.
