Constructive Pathologies: Humidities, Craps and Settlements in Existent Buildings

1. The Importance of Correct Diagnosis

In more than 30 years of real estate expertise, I have proven an uncomfortable truth: 85% of repairs of constructive pathologies fail because symptom is diagnosed, not the cause. Painting a moisture without removing the water source is like putting a tin in an infected wound: the problem will return, more serious and more expensive.

At Prop Trust Verified we apply a forensic methodology that goes beyond visual inspection. We use advanced diagnostic technology (termography, georade, humidity measurements, material tests) to identify the root cause of each pathology before proposing solutions.

2. The 4 Types of Humidity in Buildings

Humidity is the most common pathology in buildings (presents 60% of the properties over 20 years old). But not all humidity is equal, and each type requires a specific solution.

2.1. Humidity by Ascendant Capilarity

It occurs when the ground water rises by the pores of the construction materials (white, concrete, stone) by capillary action. It is characteristic of ancient buildings without waterproof barrier in the foundation.

Symptoms: Moisture stains at the base of the walls (up to 1-1.5m high), saline eflorescences, unfinished coatings, persistent moisture odor.

Advanced diagnosis: Measurements with impedance and carbide higrometry, infrared thermogram to map the wet front, hygroscopic salt analysis.

Technical solutions:

• Active electroosmosis: System that reverses the electric polarity of the wall, repeling the water. Cost: 3,000€ – 15,000€ according to length of wall.
• Injected chemical barrier: Pressure silains/siloxans injection at the base of the wall. Cost: 150€ – 300€ per linear metro.
• Replacement of the socket: A radical solution that consists of cutting the wall and intercaling a waterproof foil. Cost: 400€ – 800€ per linear metro.

2.2. Humidity by Lateral Filtration

It affects basements, underground garages and buried walls. The ground water penetrates laterally by fissures, sealed joints or porosity of the concrete.

Symptoms: Charges on soleras, stains on buried walls, drip on constructive boards, proliferation of molds.

Advanced diagnosis: Inspection with joint endoscopes, permeability tests, monitoring of groundwater levels with piezometers.

Technical solutions:

• Negative impermeabilization (crystal mortars): Interior application of mortars that react with water forming waterproof crystals. Cost: 150€/m2.
• Positive implantation (exterior): Perimeter excavation and waterproof foil application. Cost: 200€ – 400€/m2.
• Permetral drainage: French drain installation with geotextile and perforated pipe. Cost: 150€ – 300€ per linear metro.

2.3. Humidity by Condensation

It occurs when the inner water vapor is condensed into cold surfaces (thermal poles, poorly isolated walls, corners). It is the most common humidity in poorly ventilated modern housing.

Symptoms: Water drops in windows, black mold stains in corners and rears of cabinets, smell of enclosed, breathing problems in occupants.

Advanced diagnosis: Infrared termography to identify thermal bridges, relative humidity measurements and temperature (point of dew), pondering tests (blower door test).

Technical solutions:

• Thermal insulation (SATE or shuttered): Removing thermal bridges. Cost: 180€/m2.
• Mechanical ventilation with heat recovery (VMC): Air renewal without energy loss. Cost: 3,000€ – 8,000€ per house.
• Natural controlled ventilation: Installation of airers and extractors. Cost: 500€ – 2,000€.

2.4. Humidity by Filtration from Cover or Facilities

Water that penetrates from defective decks, poorly waterproofed terraces, or plumbing/heating facilities with leaks.

Symptoms: Roofs, unfinished vertical paraments, occasional droplets, increased consumption of water without apparent cause.

Advanced diagnosis: Deck controlled flood tests, inspection with thermogram chambers, gas tracer for leak detection in pipes.

Technical solutions: Depending on the origin, from localized repair of waterproofing (500€ – 2,000€) to full replacement of deck (15,000€ – 80,000€).

3. Cracks: Diagnosis by Patterns

The cracks It’s the language that buildings talk to us about. Each pattern of fissure tells a different story about the tensions that the structure suffers. A forensic expert should know how to read that language.

3.1. Surface Fissures (Retraction)

They are fine fissures (≤2mm wide) that affect only the coating. They are produced by retraction of the mortar or plaster during the friction. Do not compromise the structure and are repaired with elastic masks or reinforcement with fiberglass mesh.

3.2. Active cracks vs. Stabilized cracks

Before repairing any crack, it is essential to determine whether it is active (it continues to evolve) or stabilized (it does not grow). To do this:

• Plaster witnesses: Plaster bridges are placed through the crack. If they break in weeks/months, the crack is active.
• Mechanical gauges: Precision devices that measure the millimetric evolution of the opening.
• Electronic monitoring: Sensors that continuously record the opening depending on temperature and humidity.

3.3. Type of Structural Craps

The direction and pattern of the cracks reveals the structural cause:

• Vertical cracks on pillars: Axial overload or armor corrosion.
• Diagonal cracks (45°) in beams: Cutting failure, very dangerous.
• Horizontal cracks on walls: Side push (earth, wind) or pandeo.
• Staired cracks on the facade (scallar type): Differential foundation settlements.
• Radial cracks in forged: Pointing in encounter with pillars.
• “X” cracks on walls: Seismic or wind forces.

4. Asentamientos Diferenciales: Causas y Soluciones

Los asentamientos diferenciales son la causa más frecuente de patologías estructurales graves en edificios. Se producen cuando diferentes zonas del edificio se hunden a ritmos distintos, generando tensiones que la estructura no puede absorber.

4.1. Causas Geotécnicas

• Suelos expansivos (arcillas): Cambios de humedad que provocan hinchazones y retracciones del terreno. Muy frecuente en la cuenca mediterránea.
• Karst y cavernas: Disolución de rocas solubles (calizas, yesos) que crea huecos subterráneos. Catastrófico en Murcia, Alicante, Teruel.
• Nivel freático variable: Oscilaciones del nivel de agua que modifican la capacidad portante del terreno.
• Rellenos antrópicos: Terrenos ganados al mar o rellenos con escombros mal compactados.

4.2. Causas Antrópicas

• Excavaciones próximas: Obras de metro, aparcamientos subterráneos o cimentaciones vecinas que descalzan la cimentación existente.
• Fugas de agua en redes: Roturas de tuberías que lavan el terreno bajo la cimentación.
• Sobrecargas no previstas: Ampliaciones o cambios de uso que aumentan las cargas sobre la cimentación.
• Vibraciones: Tráfico intenso, obras cercanas, maquinaria industrial.

4.3. Soluciones Técnicas Avanzadas

La tecnología ha revolucionado las soluciones para asentamientos. Ya no es necesario recurrir a costosas y molestas bajo-cimentaciones tradicionales:

Inyecciones de Resina Expansiva (URETEK, Geosec)

Tecnología italiana que inyecta resinas expansivas en el terreno, compactándolo y elevando el edificio milimétricamente. Ventajas: sin obras, rápido (1-3 días), preciso (control láser en tiempo real). Coste: 8.000€ – 60.000€ según extensión.

Micropilotes de Acero

Perforación e hinca de micropilotes de acero hasta estrato resistente, con posterior recalce de la cimentación. Solución definitiva para casos graves. Coste: 25.000€ – 200.000€.

Jet-Grouting

Inyección de lechada de cemento a alta presión que crea columnas de suelo-cemento mejorando la capacidad portante. Para casos complejos con acceso limitado. Coste: 40.000€ – 300.000€.

5. Técnicas de Reparación y Costes Reales (2026)

Los precios indicados son orientativos para el mercado español en 2026. Pueden variar significativamente según ubicación, accesibilidad y complejidad.

6. Casos Prácticos: Del Diagnóstico a la Solución

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