CTE DB-HS6 Regulation
Spanish Technical Building Code - Radon Protection
Complete guide to Spanish radon protection regulations in construction. CTE DB-HS6 establishes mandatory requirements for new buildings and renovations in radon risk zones.
What is CTE DB-HS6?
The Basic Document on Health - Section 6 (DB-HS6) of the Technical Building Code establishes requirements for protection against radon exposure inside buildings. It was approved by Royal Decree 732/2019 on December 20, 2019, as transposition of Directive 2013/59/EURATOM.
This regulation has been mandatory since September 16, 2020 for all new construction and for extensions, changes of use and renovations of existing buildings located in municipalities classified as risk zones.
The main objective is to limit the foreseeable risk of inadequate radon exposure from the ground inside buildings, establishing a maximum reference level of 300 Bq/m³ as annual average.
Key points of the regulation
Entry into force
Mandatory since September 16, 2020 for all new construction in risk zones.
Reference level
The maximum limit set is 300 Bq/m³ as annual average radon concentration.
Scope of application
New buildings, extensions, changes of use and renovations in classified zones.
Legal basis
Royal Decree 732/2019 transposing European Directive 2013/59/EURATOM.
Risk zones
Spain is divided into Zone I and Zone II according to the ground's radon potential.
Mandatory verification
After completing construction, verification of measures through measurement is mandatory.
Radon zone classification
The CTE classifies Spanish municipalities into two zones according to the ground's radon potential, determining mandatory protection measures for each case.
Zone I
Moderate radon risk
Municipalities where the annual average radon concentration in buildings may exceed 300 Bq/m³. Basic protection measures are required.
Mandatory requirements:
- Protection barrier between the ground and habitable areas
- Alternatively: air chamber ventilated to the outside
- Verification through measurement after completing construction
Zone II
Priority action - High risk
Municipalities with significant radon presence where enhanced protection measures are required. Higher probability of exceeding the reference level.
Mandatory requirements:
- Protection barrier between the ground and habitable areas
- Mandatory additional system: ventilated containment space
- Or ground depressurization system (active or passive)
- Verification through measurement after completing construction
Check Your Radon Zone
Search for your municipality to know its radon classification
Scope of application
CTE DB-HS6 clearly defines which buildings and situations are subject to its radon protection requirements.
Applies to:
- New buildings in Zone I and Zone II
- Extensions of existing buildings in risk zones
- Changes of use involving habitable areas
- Renovations affecting the building envelope in contact with the ground
- Comprehensive rehabilitations in classified zones
Exceptions:
- Non-habitable areas (garages, storage without prolonged use)
- Areas separated from ground by existing ventilated air chamber
- Buildings located outside Zone I and Zone II
- Minor renovations not affecting the envelope
CTE Detector Calculator
Calculate the number of detectors needed to verify CTE DB-HS6 compliance in your building.
Calculate required detectorsProtection measures
CTE DB-HS6 establishes different technical solutions for radon protection, varying according to the risk zone.
Protection barrier
Continuous radon-impermeable membrane placed under the slab or crawl space, sealing all joints and penetrations.
Zone I and Zone IIVentilated air chamber
Space ventilated to the outside located between the ground and habitable areas, with permanent ventilation openings.
Zone I (alternative)Ventilated containment space
Additional air chamber under the protection barrier, connected to the outside through ventilation ducts.
Zone II (mandatory)Passive depressurization system
Collection sump under the slab connected to a vertical duct to the roof, prepared for future activation.
Zone II (alternative)Active depressurization system
System with mechanical extractor maintaining negative pressure under the slab, evacuating radon outside.
Zone II (if measurement > 300 Bq/m³)Penetration sealing
Airtight treatment of all joints, cracks and installation penetrations crossing the barrier.
Zone I and Zone IIMeasurement requirements
Verification through measurement is mandatory to check the effectiveness of implemented protection measures.
Measurement conditions
- Minimum exposure period: 2 months (3 recommended)
- Detectors placed in habitable areas in contact with the ground
- Avoid holiday periods or prolonged closure
- Minimum 2 detectors for areas under 200 m²
Laboratory requirements
Measurements must be performed by a laboratory with accreditation according to UNE-EN ISO/IEC 17025, granted by ENAC or equivalent recognized entity.
Radonova Laboratories is recognized by the Nuclear Safety Council (CSN) as an accredited laboratory, meeting all requirements for official measurements according to CTE DB-HS6.
Frequently asked questions
When is CTE DB-HS6 mandatory?
+
It has been mandatory since September 16, 2020 for all new construction, extensions, changes of use and renovations affecting the envelope in contact with the ground, provided the building is in a municipality classified as Zone I or Zone II.
What happens if my municipality is not classified?
+
If your municipality is not classified as Zone I or Zone II, there are no mandatory requirements under the CTE. However, radon measurement is recommended, especially in homes with basements or in direct contact with the ground, as localized elevated concentrations may exist.
Is measurement mandatory after completing construction?
+
Yes, verification through measurement is mandatory to check that implemented protection measures are effective and that radon concentration remains below the reference level of 300 Bq/m³.
How long should the measurement last?
+
The measurement must last a minimum of 2 months, though 3 months is recommended for better accuracy, preferably during the period from October to May. This provides a representative value of the annual average, compensating for seasonal variations.
What if the measurement exceeds 300 Bq/m³?
+
If 300 Bq/m³ is exceeded, additional corrective measures must be implemented (such as activating a passive depressurization system or improving ventilation) and a new measurement must be taken to verify effectiveness.
Can I do the measurement myself?
+
For the measurement to have official validity under the CTE, it must be performed by an ISO 17025 accredited laboratory. Detectors must be supplied and analyzed by that laboratory. Private measurements without accreditation are not valid for regulatory compliance.
Need to comply with CTE DB-HS6?
We are official distributors of Radonova, CSN-accredited laboratory. We help you perform measurements required for Technical Building Code compliance.