Soluciones contra la humedad<\/a><\/em><\/span><\/span><\/p>\nBefore I share that magic list of four strategies you can implement, let me introduce myself in case we haven\u2019t met yet: I am Esther Rovira (ERA architects), an architect and passive house designer based in Barcelona and Catalonia, specializing in unique passive houses and full, turnkey sustainable renovations. In this article\u2014”Anti-damp Ground Floor Renovation in Barcelona<\/em>“\u2014you will find these five key points clearly explained:<\/p>\n\n- Strategy 1: With and WITHOUT renovation<\/li>\n
- Strategy 2: With and WITHOUT renovation<\/li>\n
- Strategy 3: With and WITHOUT renovation<\/li>\n
- Strategy 4: With and WITHOUT renovation<\/li>\n
- The legal framework and how it affects you<\/li>\n
- Conclusions<\/li>\n
- Your next step<\/li>\n<\/ol>\n
So let’s dig into it!<\/p>\n
Strategy 1: Insulate the floor (Stopping cold and rising damp)<\/b><\/h2>\n
The floor of a ground-level apartment directly on an uninsulated slab acts as a constant thermal bridge. In autumn and winter, the cold floor comes into contact with warm indoor air, causing condensation humidity on the surface.<\/span><\/p>\nOption A: Full Renovation (Insulating foam and insulated slab)<\/b><\/h3>\n
If you are immersed in a complete renovation, do not skimp on the base. The ideal approach consists of adding at least <\/span>5 cm to 8 cm of extruded polystyrene (XPS) panels<\/b> under the final flooring (parquet, microcement, or stoneware).<\/span><\/p>\n\n- Pros:<\/b><\/li>\n<\/ul>\n
\n- \n
\n- Permanently eliminates the cold entering from the subsoil.<\/span><\/li>\n
- Drastically improves the home’s energy efficiency, reducing heating bills by up to 15-20%.<\/span><\/li>\n
- Definitive solution for the entire lifespan of the property.<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n- Cons:<\/b><\/li>\n<\/ul>\n
\n- \n
\n- Requires losing height (between 8 and 12 cm) or excavating (with its corresponding demolition and debris removal).<\/span><\/li>\n
- High initial financial investment.<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n- Estimated cost in 2026:<\/b> Between <\/span>\u20ac65 and \u20ac110 per m\u00b2<\/b> (includes demolition, 50mm XPS insulation, concrete slab layer, and medium-grade flooring).<\/span><\/li>\n<\/ul>\n
Option B: Without Renovation (Technical textiles and natural wool rugs)<\/b><\/h3>\n
If you are not carrying out work this year, the temporary strategy consists of placing textile thermal barriers in areas where you spend the most hours. Use thick, high-grammage natural wool rugs under the bed or in the desk area if you work from home. You can place a plastic sheet under the rug to protect it, but you will need to mop up the water that condenses under the sheet.<\/span><\/p>\n\n- Pros:<\/b><\/li>\n<\/ul>\n
\n- \n
\n- Immediate setup without dust or building permits.<\/span><\/li>\n
- Warm feeling to the touch.<\/span><\/li>\n
- Economical and reusable if you move (perfect if renting).<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n- Cons:<\/b><\/li>\n<\/ul>\n
\n- \n
\n- Does not eliminate subsoil dampness; it only delays heat transfer.<\/span><\/li>\n
- Requires rigorous maintenance: if the rug absorbs ambient humidity without airing out, dust mites can accumulate. It is essential to wipe away water under the sheet and air out the room daily.<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n- Estimated cost in 2026:<\/b> Between <\/span>\u20ac150 and \u20ac450<\/b> per large format rug (200×300 cm) in 100% natural wool.<\/span><\/li>\n<\/ul>\n
<\/p>\n
Strategy 2: Inject moisture blockers (Chemical barrier against rising damp)<\/b><\/h2>\n
Rising damp occurs when groundwater rises through the porous material of walls (brick, concrete, or stone). This process dissolves salts that end up destroying paint, which is precisely what is seen on ground-floor walls: swollen or peeling paint.<\/span><\/p>\nRecommended Option: Hydrophobic resin injections (With and WITHOUT renovation)<\/b><\/h3>\n
Fortunately, this treatment does not require tearing down walls and can be applied in both renovations and inhabited homes. It consists of drilling a series of holes low down at the base of the wall (every 10-12 cm) to inject silane- and siloxane-based gels. These compounds expand through the pores of the brick and mortar, crystallizing and creating a continuous horizontal barrier that prevents moisture from rising further.<\/span><\/p>\n\n- Pros:<\/b><\/li>\n<\/ul>\n
\n- \n
\n- Can be applied quickly in 1 or 2 days without having to leave the home.<\/span><\/li>\n
- Very high effectiveness proven in typical brick walls of Eixample, Gr\u00e0cia, and Ciutat Vella.<\/span><\/li>\n
- Manufacturer and installer warranty that usually ranges between 10-20 years.<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n- Cons:<\/b><\/li>\n<\/ul>\n
\n- \n
\n- Requires a drying period for the wall that can last several months before repainting the damaged surface.<\/span><\/li>\n
- If walls are made of thick, heterogeneous natural stone (old load-bearing walls over 50 cm thick), injection requires a more complex preliminary technical study.<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n- Estimated cost in 2026:<\/b> Between <\/span>\u20ac110 and \u20ac180 per linear meter<\/b> of treated wall (varies according to wall thickness).<\/span><\/li>\n<\/ul>\n
Strategy 3: Insulate walls of courtyards and communal entrances (Lateral dampness)<\/b><\/h2>\n
The vast majority of ground-floor homes in Barcelona adjoin communal hallways, damp lightwells, or adjacent land at different heights. In these cases, dampness enters laterally.<\/span><\/p>\nOption A: Full Renovation (Self-supporting wall lining with water-repellent insulation)<\/b><\/h3>\n
The professional solution is to build a false interior wall (water-resistant plasterboard lining), filling the cavity with mineral wool or rock wool. <\/span>Key point:<\/b> in the first 50 cm in direct contact with the floor, the insulation must be waterproof, such as extruded polystyrene (XPS).<\/span><\/p>\n\n- Pros:<\/b><\/li>\n<\/ul>\n
\n- \n
\n- Complete elimination of cold walls and surface condensation.<\/span><\/li>\n
- Allows hiding electrical and plumbing installations.<\/span><\/li>\n
- Extra acoustic insulation against neighborhood or street noise.<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n- Cons:<\/b><\/li>\n<\/ul>\n
\n- \n
\n- Reduces the room size by about 7 cm per wall.<\/span><\/li>\n
- Requires complete dry construction, jointing, and painting.<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n- Estimated cost in 2026:<\/b> Between <\/span>\u20ac55 and \u20ac90 per m\u00b2<\/b> of wall (including frame, water-repellent insulation, and finish).<\/span><\/li>\n<\/ul>\n
Option B: Without Renovation (Breathable paints and decorative panels)<\/b><\/h3>\n
To get by without work this autumn, there are two main alternatives:<\/span><\/p>\n\n- Lime-based or anti-condensation paints:<\/b> Natural lime paints are alkaline and breathable, preventing mold growth naturally. Anti-condensation paints incorporate glass microspheres that slightly break the thermal bridge.<\/span><\/li>\n
- Cork or wood panels:<\/b> Applied to strategic walls (such as behind the bed headboard), they act as temporary thermal and moisture regulators.<\/span><\/li>\n<\/ol>\n
\n- Pros:<\/b><\/li>\n<\/ul>\n
\n- \n
\n- Low cost and possibility of execution by the user (DIY).<\/span><\/li>\n
- Aesthetic improvement of worn-out rooms.<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n- Cons:<\/b><\/li>\n<\/ul>\n
\n- \n
\n- Strictly <\/span>temporary<\/b> solution. If lateral dampness is severe, cork or wood will eventually warp or detach after a single very humid winter.<\/span><\/li>\n
- Paint does not solve the underlying issue; it only slows visible deterioration in the short term.<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n- Estimated cost in 2026:<\/b><\/li>\n<\/ul>\n
\n- \n
\n- Anti-condensation\/lime paint: <\/span>\u20ac12 to \u20ac25 per liter<\/b> (material cost).<\/span><\/li>\n
- Decorative cork\/wood panels: <\/span>\u20ac30 to \u20ac70 per m\u00b2<\/b>.<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
Strategy 4: Ventilation (The most critical and underrated factor)<\/b><\/h2>\n
Even if you insulate the floor and walls, a human at rest constantly exhales water vapor. Added to this are showers, cooking, and drying clothes indoors. If the dwelling lacks adequate ventilation, the air becomes saturated, and moisture deposits on the coldest areas of the property.<\/span><\/p>\nOption A: Full Renovation (Mechanical Ventilation with Heat Recovery – MVHR)<\/b><\/h3>\n
This is the crown jewel of modern sustainable building and an essential recommendation in any comprehensive renovation project. A dual-flow MVHR system continuously extracts stale air from bathrooms and kitchens while supplying fresh, filtered air from the street into living rooms and bedrooms.<\/span><\/p>\nIn addition, you can incorporate a <\/span>heat recovery unit<\/b>. The outgoing stale air tempers the incoming fresh air without mixing, reducing heating needs in winter (in summer, a bypass is used to avoid this process and keep things cool).<\/span><\/p>\n\n- Pros:<\/b><\/li>\n<\/ul>\n
\n- \n
\n- Guarantees total air renewal in the home every 2-3 hours, 24 hours a day.<\/span><\/li>\n
- Filters pollen, city pollution (PM2.5), and mold spores before they enter the home.<\/span><\/li>\n
- Massive energy savings: recovers up to 80-90% of indoor heat, drastically reducing heating usage.<\/span><\/li>\n
- Avoids having to open windows in the middle of winter and lose heat.<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n- Cons:<\/b><\/li>\n<\/ul>\n
\n- \n
\n- Requires installation of distribution ducts through false ceilings throughout the house.<\/span><\/li>\n
- Significant initial investment.<\/span><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
\n- Estimated cost in 2026:<\/b> Between <\/span>\u20ac4,500 and \u20ac8,500<\/b> (for a home of about 70-90 m\u00b2; includes centralized unit, ductwork, vents, and technical installation).<\/span><\/li>\n<\/ul>\n
Option B: Without Renovation (Manual cross ventilation and dehumidifiers)<\/b><\/h3>\n
If you do not have an automated system, you must resort to strategic manual ventilation: open windows on opposite facades to generate air drafts (<\/span>cross ventilation<\/span><\/i>) for at least 45 to 60 minutes a day, preferably split into two sessions (morning and evening). If the apartment is internal or lacks opposite windows, use fans in windowless rooms directed toward the doorway to force air circulation.<\/span><\/p>\nAs support, using <\/span>portable electric dehumidifiers<\/b> (compressor or desiccant types) is practically mandatory in Barcelona ground-floor apartments during autumn months.<\/span><\/p>\n\n- Pros:<\/b><\/li>\n<\/ul>\n