How to Build a Moisture-Resistant House in Galicia
In Galicia, moisture isn’t “a minor detail”: it’s a design criterion. If it’s controlled from the design phase through construction, you avoid mold, bad odors, material deterioration, and that “damp cold” feeling that forces you to turn up the heating.
Key idea: moisture enters in 3 ways, and each must be tackled differently:
From the ground (rising damp / groundwater)
From outside (rain + wind / water ingress)
From inside (condensation due to thermal bridges and insufficient ventilation)
What’s really at stake
Durability: deterioration of masonry, corrosion, detachments, and defects in finishes.
Health and comfort: fungi and dust mites; worse thermal comfort if cold surfaces cause condensation.
Energy use: more moisture = higher heating demand and lower comfort.
The 7 keys
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Foundations and “dry” wall bases (rising damp under control)
A well-executed damp-proof barrier at the base of the façade: continuous, unbroken, and correctly detailed.
Waterproofing of below-ground walls (from the outside whenever possible) + mechanical protection.
Perimeter drainage when required (depending on soil and groundwater level): drain pipe, geotextile, gravel, and a guaranteed outlet.
On site: this is where you gain (or lose) years of service life. -
Floor in contact with the ground: continuity and perfect junctions
Slab/ventilated crawl space with a coherent solution: membrane, sealed junctions, and continuity with the walls.
Watch service penetrations: if they’re not properly sealed, they become a highway for water and vapor. -
Façades that manage water (and allow drying)
It’s not just about “waterproofing”: it’s about blocking rain entry and allowing the building envelope to dry.
Pay special attention to plinths, wall bases, copings, junctions with windows/doors, and changes in materials.
Avoid solutions that “seal” the wall without considering vapor behavior: you can create internal condensation. -
Windows and doors: 80% is installation, not the brand
“System” installation, not just silicone:
Exterior sealing resistant to water and wind
Interior sealing more airtight
Proper water management at the support (sill/drip flashing with slope and drip edge)
Check junctions: jambs, lintels, subframes, and fixings. -
Roof: slope, junctions, and critical details
No “eyeballing”: design and build with adequate slopes so water doesn’t pond.
Under the covering: ensure waterproofing continuity and pay attention to:
valleys
chimneys and vents
junctions with parapets
gutters and downpipes (sizing and maintenance) -
Condensation: insulation + continuity + ventilation
Continuous insulation reduces thermal bridges → fewer cold surfaces → less mold.
Avoid interior “patches” that create dew-point risks.
Ensure proper ventilation: supply air in dry rooms and extract in bathrooms/kitchen. If you want real stability, consider mechanical ventilation with heat recovery (MVHR). -
Finishes and “critical details”: where most issues start
Terraces and balconies: slopes toward drains, waterproofing properly turned up at parapets, and treated joints.
Railings, wall penetrations, and fixings: always use a watertight solution planned before execution.
Copings on walls and parapets: prevent water from running down the façade.
Common mistakes (and how to avoid them)
Relying on paint or silicone: it doesn’t last and fails at joints.
Insulating only from the inside in exposed areas: increases thermal bridges and condensation.
Poor coordination between trades (façade–joinery–waterproofing): without shared detailing, defects appear.
Why trust Abeiro?
At Abeiro, we design and build for the real Atlantic climate: wind-driven rain, high ambient humidity, and details that—if executed poorly—cause problems fast. We work with a full-system approach: ground + envelope + ventilation + execution control.
