The heart of the system: a sealed suction unit installed in a utility room. It sucks Radon from the subsoil and expels it outside.
Radon Remediation in Existing Buildings
Soil Depressurization
The most effective and least invasive remediation technique to protect your home from Radon gas without demolishing floors.
What is Depressurization: Advanced Remediation Techniques
From the 'Gold Standard' SSD to Pressurization: applied engineering for your home's health.
Radical Remediation without Demolition
Forget invasive construction sites, dust, and dismantled floors. Active Soil Depressurization (SSD) is the most advanced engineering approach to rehabilitating existing buildings. Instead of trying to seal every micro-crack (often an impossible task), this technique acts on the physical cause of the problem: the pressure difference.
The goal is to reverse airflows: by installing strategic suction points, we create a negative pressure field in the ground that captures Radon before it can enter inhabited spaces, safely expelling it outside.
Diagnostic Precision (Photo)
As highlighted in the photo above, the heart of our methodology is the measurement of the Pressure Differential. Using digital micromanometers sensitive to Pascals, we verify that the "depression field" generated by the fan extends uniformly under the entire slab. This scientific approach ensures that every room is protected, avoiding "trial and error" installations and energy waste.
The Pressurization Barrier
The diagram below illustrates the complementary strategy: Pressurization. By introducing filtered outside air, the building becomes slightly "pressurized" relative to the ground. This invisible barrier (of only 2-4 Pascals) counteracts the natural Stack Effect and physically pushes Radon gas back into the subsoil, preventing its ascent.
Advanced Criticality Management
Manipulating building pressures requires expert competence. Poorly managed pressurization can drive internal humidity into walls, causing serious interstitial condensation damage and hidden mold. Conversely, excessive depressurization can cause backdrafting of dangerous fumes from boilers and fireplaces. Our protocol includes rigorous balancing to ensure absolute safety.
Radon Remediation: Intervention Techniques and Guaranteed Results
In-depth look at Sub-Slab Depressurization (SSD) and Crawl Space Ventilation.
1. Efficiency: Active Depression vs Passive Dilution
While natural ventilation (opening windows) is limited to diluting the gas (often losing precious heat), our technique creates a targeted active depression under the building. This physically prevents upstream gas ascent, ensuring maximum safety with minimum energy consumption.
2. Tailored Solutions: SSD or Crawl Space Ventilation
Every building is unique. For slab-on-grade or basement foundations, we use SSD (Sub-Slab Depressurization) with targeted suction pits in the ground. If a crawl space is present, we opt for Forced Ventilation of cavities, enhancing existing air exchange to sweep away accumulated Radon.
3. Certified Results: Concentration Collapse
The graph to the side (red line) shows immediate system efficacy. As soon as depressurization is activated, concentrations collapse vertically, going from dangerous values (>1000 Bq/m³) to absolute safety levels (<100 Bq/m³), stable 365 days a year regardless of weather.
Radon Prevention: Sealing Strategies and Air Flow Management
1. Blocking Radon Infiltration by Convection
Most Radon (over 90%) penetrates buildings through convection, carried by air currents. The primary cause is the pressure difference between the ground and the interior, generated by heating ("Stack Effect") and wind. To block gas entry, it is imperative to actively manage these forces.
- ● Neutralize Internal Depression: Prevent the building from acting like a vacuum cleaner, sucking gas from the ground through cracks and joints.
- ● Create Positive Overpressure: By introducing treated air, flow is reversed: air pushes outwards, creating an insurmountable pneumatic barrier for Radon.
- ● Strategic Foundation Ventilation: Intercept and dilute gas directly in the crawl space or under the slab before it can reach the inhabited slab.
2. Envelope Airtightness and Energy Savings
A modern building must be airtight not to lose heat, but airtightness can trap pollutants. Our remediation perfectly balances these needs: we seal gas entry points (passive sealing) and mechanically control air exchange, ensuring healthiness without compromising energy efficiency class.
Energy Optimization: Passive Sealing vs Active Ventilation
Efficiency is our priority. Relying only on fans can be expensive. For this reason, we first perform meticulous passive sealing of all ground contact points (hydraulic passages, cracks, joints). Every closed crack is one less cubic meter of air the active system must treat, reducing electricity consumption by up to 50%.
Advanced Instrumental Diagnostics
We don't work "by guess". Every building has a unique radon footprint, determined by geology and construction. Before designing the system, we perform precise measurements to map gas distribution in the subsoil and calculate exact soil permeability. Only in this way can we guarantee the final result.
1. Subsoil Mapping (Sniffing)
Through micro-holes in the slab, we insert probes to take air samples directly from the ground ("soil gas"). This allows us to identify maximum accumulation points (hotspots) and understand where to strategically place suction pits to maximize efficiency.
2. Pressure Field Extension Test (PFE)
Using high-sensitivity digital micromanometers, we simulate suction and measure pressure drop (in Pascals) at various points in the house. This fundamental test certifies that the generated depression reaches every corner of the foundations, ensuring no uncovered zones remain from which gas could rise.
Benefits of Depressurization
Why choose SSD for your existing home.
No Demolition
No need to break home floors. The intervention is minimally invasive and preserves internal finishes.
Energy Efficiency
Unlike room ventilation (opening windows), SSD does not disperse internal heat but only sucks air from the subsoil.
Absolute Silence
Modern fans are extremely quiet and, if positioned externally, are imperceptible from inside.
Low Maintenance
Once installed, the system only requires periodic checks of operation and depression (U-tube manometer).
Continuous Monitoring
The system can be equipped with a U-tube manometer to visually verify at any moment that depression is active.
Adaptability
Works on crawl spaces, slab-on-grade, basements, and semi-basements. It is the most versatile solution for existing buildings.
Frequently Asked Questions about Depressurization
What is soil depressurization?
Is it necessary to break the floors?
Is the system noisy?
How much does a depressurization system cost?
Does it work on all houses?
How long does installation take?
Have other questions?
Back to general remediation FAQ or contact us for specific advice.
Back to Remediation FAQRadon problem at home?
Contact us for a depressurization feasibility assessment.