Multilayer radon-impermeable structure for construction applications

Abstract

The present disclosure relates to a multilayer radon-impermeable structure for construction applications. The present disclosure relates to a multilayer radon-impermeable structure for construction applications comprising: a substrate layer; a framework set applied over the substrate layer, with spaces between the components of said framework set to allow for air circulation and fluid drainage; a first layer of radon-impermeable material applied directly over the framework set; a second layer of radon-impermeable material applied over the first layer of radon-impermeable material, wherein the second layer of radon-impermeable material is applied in a crosswise orientation relative to the first layer for additional reinforcement and ensuring continued protection in case of failure of the first layer.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a multilayer radon-impermeable structure for construction applications.BACKGROUND

[0002] Radon is a noble, colourless, odourless, and radioactive gas that originates from the natural decay of uranium minerals in the soil. It is one of the primary sources of natural radiation to which humans are exposed and is the second leading risk factor for lung cancer after smoking, according to the World Health Organization (WHO). Due to its higher density than air, radon tends to accumulate in underground areas, such as basements and subfloors, where concentrations can reach dangerous levels, posing a significant health threat to the occupants of buildings.

[0003] While preventing radon exposure is critical, current construction methods, such as physical barriers and ventilation systems, often fail to provide effective and long-lasting protection. The presence of cracks, structural imperfections, or material wear over time can compromise the effectiveness of these systems, allowing radon to infiltrate indoor spaces and negatively impact long-term health.

[0004] Several approaches exist for mitigating radon infiltration, including both active and passive ventilation, which are commonly used but rely on regular maintenance and may be ineffective in areas with high radon concentrations or adverse environmental conditions. Traditional physical barriers, such as plastic sheeting or waterproofing films, may also fail due to wear or mechanical damage. Additionally, conventional sealing and waterproofing systems, while widely used for water infiltration issues, were not specifically designed to address radon, and therefore do not ensure the airtightness required to block the gas effectively.

[0005] Simple assembly architecture does not account for potential failure points caused by cracks or imperfections, thus failing to provide a continuous and effective seal.

[0006] In the context of indoor air quality and radiation exposure, acceptable reference values for radon diffusion are generally defined in terms of activity concentration expressed in becquerels per cubic metre (Bq / m 3< ). In line with recommendations commonly adopted at international level, reference concentrations of approximately 400 Bq / m 3< are typically considered acceptable for existing buildings, whereas lower reference values of about 200 Bq / m 3< are generally applied to new constructions. These values are not absolute and may vary depending on the regulatory framework in force in each country.

[0007] By way of illustration, several national authorities have established action levels within these ranges. For existing buildings, reference concentrations are commonly set between about 148 Bq / m 3< and 500 Bq / m 3< , while for buildings under construction the corresponding values are often lower, typically ranging from about 50 Bq / m 3< to 200 Bq / m 3< , with certain jurisdictions applying differentiated limits depending on building use, such as residential, educational or occupational environments. For example, some countries apply higher thresholds for workplaces than for dwellings, whereas others impose uniform limits regardless of use. In a few cases, particularly stringent values are defined for new buildings, reflecting a preventive approach at the design and construction stage.

[0008] Overall, the majority of European countries and other industrialised regions converge on reference levels broadly consistent with guidance issued by the World Health Organization, which recognises that reducing radon concentrations, particularly in new buildings, is an effective measure for limiting long-term exposure. The values cited herein reflect internationally recognised reference concentrations reported by the World Health Organization in 2007 and serve as indicative benchmarks rather than fixed technical constraints, allowing adaptation to national legislation and specific application contexts.

[0009] The document KR101969703B1 discloses the building floor foundation construction method for blocking and removing radon gas, which can prevent gas-phased radon generated in soil under a building, and can collect radon gas and discharge and remove the same in the air to prevent the radon from flowing into the building. The building floor foundation construction method can comprise a cutting step, a vinyl installation step, a waste concrete application step, an insulator installation step, a gravel spreading step, a collection mat installation step, a collection pipe installation step, and a finishing material construction step, or can comprise the cutting step, a grade beam installation step, a soil filling step, the vinyl installation step, the waste concrete application step, the insulator installation step, the gravel spreading step, the collection mat installation step, the collection pipe installation step, and the finishing material construction step. Moreover, a membrane installation step can be further included when a measurement value of radon gas in soil is 10000 Bq / m 3< or more.

[0010] The document KR20150144074A discloses a radon blocking structure as a hollow rectangular parallelepiped structure with a joining unit, including: a first joining unit formed on one lateral surface of the structure and having at least one through-hole connected to the internal space of the structure; and a second joining unit formed on the lateral surface facing the lateral surface on which the first joining unit is formed and connected to the internal space of the structure. At least one gas inlet connected to the internal space of the structure is formed on the bottom of the structure.

[0011] These facts are disclosed in order to illustrate the technical problem addressed by the present disclosure.GENERAL DESCRIPTION

[0012] The present disclosure relates to a multilayer radon-impermeable structure for construction applications.

[0013] The present disclosure relates to a multilayer radon-impermeable structure for construction applications comprising: a substrate layer; a framework set applied over the substrate layer, with spaces between the components of said framework set to allow for air circulation and fluid drainage; a first layer of radon-impermeable material applied directly over the framework set; a second layer of radon-impermeable material applied over the first layer of radon-impermeable material, wherein the second layer of radon-impermeable material is applied in a crosswise orientation relative to the first layer for additional reinforcement and ensuring continued protection in case of failure of the first layer.

[0014] In order to ensure the effectiveness and continuity of this blocking mechanism, the first and second layers are arranged so as to extend into the surrounding wall structure by more than approximately 10 mm. This is achieved by forming recesses or grooves in the walls to receive the barrier materials, thereby integrating the layers into the wall envelope. Such integration prevents the formation of joints or linear bridges at the floor-wall interface and ensures that radon migration paths towards the interior are fully interrupted, maintaining long-term protection of the occupied space.

[0015] The disclosed technology relates to a multilayer radon-impermeable structure designed to block radon gas infiltration into buildings. Radon is a radioactive gas that infiltrates through cracks and interfaces in construction, posing significant health risks. The structure comprises at least three components: a framework set, that can be made, for example, of wooden battens, a first layer of radon-impermeable material, and a second layer of radon-impermeable material.

[0016] The technology relates to construction technologies, specifically to structures for mitigating radon gas infiltration in buildings. This technology is applicable to residential, commercial, and healthcare buildings, particularly in geologically high-risk areas, and complies with modern sustainability and public health standards.

[0017] The components of the framework set are spaced to create channels that allow for air circulation and fluid drainage. This spacing helps dissipate radon gas and ensures ventilation. The first layer is applied directly on top of the framework set, providing the initial barrier against radon infiltration while allowing fluid drainage and ventilation. The second layer is applied in a crosswise orientation in relation to the first layer, enhancing the sealing and ensuring continued protection even if the first layer is compromised.

[0018] The channels defined within the supporting structure do not become infiltration pathways for radon into the interior of the building because the structure is designed in accordance with the physical behaviour of radon gas and basic flow principles. Radon migrates preferentially along paths offering the least resistance to flow. By providing continuous protection and radon-impermeable layers on the side facing the interior of the building, the structure deliberately increases resistance to inward migration, thereby preventing radon from entering occupied spaces.

[0019] Under normal conditions, radon beneath the structure is at or close to atmospheric pressure and is not subject to forced pressurisation. Once an upper sealing configuration is established by the impermeable layers, the gas is naturally constrained to follow alternative paths. In practice, two outcomes are possible. Either the radon decays within its physical lifetime in the gaseous state, transforming into solid progeny and thereby losing its ability to migrate as a gas, or, during its gaseous lifetime, it is driven laterally towards the exterior by natural pressure and temperature gradients. Such gradients typically arise from differences between interior and exterior temperatures and from the fact that atmospheric pressure outside the building envelope is generally slightly lower than the pressure present beneath the protective layers. While radon naturally decays over time, the technical effect of the invention is achieved primarily by blocking inward migration and passively directing gaseous radon laterally towards the exterior during its gaseous lifetime.

[0020] The channels formed within the supporting structure are therefore configured as preferential evacuation routes, allowing radon to flow laterally between adjacent internal voids and to be discharged towards the exterior of the building. Because the inward path is effectively blocked by the impermeable layers, and because no forced suction or pressure differential is applied towards the interior, the channels function exclusively as controlled pathways guiding radon away from the occupied zone rather than as infiltration routes. This passive, physics-based configuration ensures that radon migration is consistently directed outward, maintaining the integrity of the indoor environment without reliance on active ventilation or mechanical systems.

[0021] Unlike active or passive ventilation systems, the channels formed by the framework set do not rely on forced airflow or pressure differentials generated by mechanical means, but instead operate solely by increasing resistance towards the interior and providing a lower-resistance path towards the exterior.

[0022] The structure is designed with a cross-layer configuration that minimizes crack alignment, preventing radon infiltration. It is resistant to moisture, temperature fluctuations, and physical wear, ensuring durability and long-term performance. The materials used are environmentally sustainable, and the structure is easy to install, without requiring rigid fixations.

[0023] This structure is suitable for foundations, walls, and floors in contact with a substrate layer, soil, particularly in high-risk geological zones, and can be used in both new constructions and retrofit projects. It offers an effective solution for mitigating radon exposure risks.

[0024] The present application disclosed a multilayer radon-impermeable structure for construction applications comprising: a substrate layer; a framework set applied over the substrate layer, with spaces between the components of said framework set to allow for air circulation and fluid drainage; a first layer of radon-impermeable material applied directly over the framework set; a second layer of radon-impermeable material applied over the first layer of radon-impermeable material, wherein the second layer of radon-impermeable material is applied in a crosswise orientation relative to the first layer for additional reinforcement and ensuring continued protection in case of failure of the first layer.

[0025] It is also disclosed a multilayer radon-impermeable structure for building construction applications comprising: a framework set applied over a substrate layer, the framework set comprising spaced structural elements configured to define lateral channels oriented towards an exterior boundary of the building; a first layer of radon-impermeable material applied directly over the framework set, the first layer of radon-impermeable material having a radon diffusion coefficient of less than 5 × 10 -13< m 2< / s; a second layer of radon-impermeable material applied over the first layer of radon-impermeable material, wherein the second layer of radon-impermeable material is applied in a crosswise orientation relative to the first layer; wherein the first and second layers extend outwardly from the framework set by at least 10 mm, and are configured to extend from the framework set into an adjacent building structure, thereby forming a continuous peripheral sealing framework preventing radon migration at floor-wall interfaces.

[0026] In an embodiment, the first layer and the second layer of the multilayer radon-impermeable structure are oriented at an angle ranging from 75° to 95° to each other, preferably from 80 to 90°, more preferably 90°.

[0027] In an embodiment, the second layer of radon-impermeable material of the multilayer radon-impermeable structure comprises a coating.

[0028] In an embodiment, the multilayer radon-impermeable structure further comprises an interstitial bonding material disposed between the first and second layers forming a gas-tight seal.

[0029] In an embodiment, the lateral channels of the multilayer radon-impermeable structure terminate at one or more discharge openings located at an exterior boundary of the building, so as to allow controlled evacuation of radon gas to the outside environment.

[0030] In an embodiment, the interstitial bonding material of the multilayer radon-impermeable structure is selected from a list consisting of bitumen-based adhesives, polyurethane sealants, specialty gas-tight sealants, and their combinations.

[0031] In an embodiment, the multilayer radon-impermeable structure further comprises a peripheral sealing framework that secure the assembly of the structure.

[0032] Along this description, it is considered that the term "peripheral sealing framework" refers to the formation of recesses in the lower lateral regions of the walls when the solution is installed at floor level. In this context, the walls are cut or grooved to a depth greater than approximately 10 mm in order to allow the first and second layers to extend into and become integrated with the wall structure. This configuration ensures that the barrier layers effectively penetrate the lateral boundaries of the floor assembly. By allowing the layers to enter the walls, the formation of gaps or linear bridges at the floor-wall interface is prevented. Such bridges would otherwise constitute significant preferential pathways for radon gas infiltration, particularly given that wall surfaces are rarely perfectly straight and dimensional irregularities are common in existing buildings. The peripheral sealing framework therefore ensures continuity of the radon-impermeable barrier along the entire perimeter of the floor. As a result, radon gas migration is consistently directed away from the interior of the building and towards an external boundary, rather than into zones intended for human presence and occupation. This peripheral sealing approach is thus essential to guaranteeing that radon flow is channelled towards the exterior, maintaining safe indoor conditions and preventing exposure in inhabited areas.

[0033] In an embodiment, the framework set of the multilayer radon-impermeable structure comprises a material selected from a list consisting of environmentally safe materials, wood, wooden battens, lignocellulosic materials, and their combinations.

[0034] In an embodiment, the multilayer radon-impermeable structure further comprises a levelling material disposed beneath the first layer to address surface irregularities.

[0035] In an embodiment, the multilayer radon-impermeable structure further comprises an intermediate reinforcement layer between the first and second layers for additional mechanical stability.

[0036] In an embodiment, the radon diffusion coefficient of the first layer of the multilayer radon-impermeable structure is less than 5 x 10 -13< m 2< / s .

[0037] It is also disclosed a building comprising the described multilayer radon-impermeable structure.

[0038] It is also disclosed a method of constructing the multilayer radon-impermeable structure, comprising the following steps: placing a framework set on a substrate layer; applying a first layer of radon-impermeable material over the framework set; positioning a second layer crosswise to the primary layer.

[0039] In an embodiment, the method further comprises the step of securing the periphery of the multilayer structure with a peripheral sealing framework.

[0040] In an embodiment, the method further comprises a step of levelling the framework set before placing the first layer between the step of placing a framework set on a substrate layer and the step of applying a first layer of radon-impermeable material over the framework set.

[0041] In some embodiments, an intermediate reinforcement layer may be arranged between the first radon-impermeable layer and the second coating layer. The reinforcement layer may be formed as a fibrous mesh or scrim and serves to mechanically stabilise the coating, improve adhesion between layers, and reduce the risk of cracking due to substrate movement or curing shrinkage.

[0042] Surprisingly, the effectiveness of the disclosed structure results from the cooperative interaction between the crosswise multilayer configuration, the peripheral sealing framework extending into surrounding walls, and the laterally oriented evacuation channels. None of these features alone is sufficient to achieve the demonstrated level of radon reduction; rather, their combined configuration eliminates preferential diffusion paths, including at joints, while preventing the channels themselves from acting as infiltration routes.BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The following figures provide preferred embodiments for illustrating the disclosure and should not be seen as limiting the scope of invention. Figure 1: Schematic representation of an embodiment of a multilayer radon-impermeable structure for construction applications, showing the framework set (1), the first layer of radon-impermeable material (2), and the second layer (3) applied in a crosswise orientation relative to the first layer. Figure 2: Schematic representation the air circulation and fluid drainage (4) channels created by the spacing between the components of the framework set (1). Figure 3: Schematic representation of the first layer (2) applied directly onto the framework set (1). It represents how the first layer (2) serves as the initial barrier against radon. Figure 4: Schematic representation of the second layer (3), that reinforces the structure sealing properties and ensures continued protection against radon infiltration, even in the event of failure in the first layer (2) (i). This second layer (3) is illustrated by the application perpendicularly to the first layer (2) in (ii). Figure 5: Schematic representation positions of the measurement boxes within the school. DETAILED DESCRIPTION

[0044] The present disclosure relates to a multilayer radon-impermeable structure for construction applications.

[0045] The present disclosure relates to a multilayer radon-impermeable structure for construction applications comprising: a substrate layer; a framework set applied over the substrate layer, with spaces between the components of said framework set to allow for air circulation and fluid drainage; a first layer of radon-impermeable material applied directly over the framework set; a second layer of radon-impermeable material applied over the first layer of radon-impermeable material, wherein the second layer of radon-impermeable material is applied in a crosswise orientation relative to the first layer for additional reinforcement and ensuring continued protection in case of failure of the first layer.

[0046] The physical mechanism for blocking radon is achieved through a multilayer structural and functional configuration specifically designed to prevent the migration of radon gas into occupied interior spaces while ensuring mechanical resistance, durability and constructability. The structure comprises a load-bearing structure configured to support subsequent functional layers and to withstand the presence of occupants and applied loads of up to approximately 400 kg / m 2< . This structure simultaneously defines internal channels configured to guide radon gas laterally towards the perimeter of the building, where discharge openings are provided at the extremities, thereby promoting controlled evacuation of the gas to the exterior.

[0047] On top of said structure, a first layer is installed, comprising large-format panels, preferably having dimensions exceedingly approximately 2 by 3 metres. The use of large panels significantly reduces the number of linear joints and interfaces, which are known to constitute preferential paths for radon migration. This layer is formed from a material composition having intrinsic radon-impermeable properties, such as those defined in a previously disclosed material formulation, thereby acting as a primary diffusion barrier.

[0048] A second layer is subsequently applied above the first layer and is formed by panels of smaller dimensions, likewise presenting radon-impermeable characteristics. These panels are preferably arranged in an orientation offset, for example rotated by approximately 90 degrees relative to the panels of the first layer, in order to overlap and interrupt any remaining linear joints. This staggered configuration further reduces the formation of continuous diffusion paths, thereby increasing the overall safety and effectiveness of radon protection and isolation.

[0049] In addition to its barrier function, the upper layer is configured to provide a finished surface, eliminating the need for additional finishing materials. The exposed upper face of this layer may incorporate decorative or aesthetic finishes, including printed, impregnated or laminated decorative papers or coatings, enabling the simulation of various materials and textures while maintaining radon impermeability.

[0050] To further prevent the formation of linear bridges at the interface between the barrier structure and surrounding walls, recesses or grooves are formed in the lower lateral regions of the walls, preferably having a depth of at least 10 mm. These recesses allow the barrier layers to extend into the wall structure, thereby compensating for construction tolerances, wall deformations and misalignments, and ensuring that no unprotected joint exists at the floor-wall interface. As a result, radon flow is consistently directed away from the interior occupied zone towards the exterior, reducing human contact, exposure and inhalation to levels below those considered tolerable for human health and ensuring safe habitation in areas with elevated natural radioactivity.

[0051] Furthermore, the multilayer radon-impermeable structure takes into account the physical behaviour of radon gas, which, in its gaseous and inhalable state, has a physical half-life of less than four days before decaying into solid progeny. Once transformed into particulate form, the material no longer exhibits the capacity to migrate through the building envelope in gaseous form, further limiting the risk of indoor accumulation.

[0052] The described physical blocking mechanism, material selection and construction concept also provide enhanced resilience to perforations and mechanical damage occurring during construction or use of the building. This represents a significant advantage over conventional liquid membrane solutions, which are highly susceptible to accidental perforation and, over time, are prone to cracking and degradation, leading to a high probability of loss of radon barrier integrity.

[0053] In an embodiment, at least one of the first layer of radon-impermeable material and the second layer of radon-impermeable material of the multilayer radon-impermeable structure comprises a polymeric membrane or panel selected from the list consisting of: high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), polyvinyl chloride (PVC), thermoplastic polyolefin (TPO), ethylene propylene diene monomer (EPDM), butyl rubber, ethylene vinyl alcohol (EVOH) barrier film, and composites comprising a metallised layer and / or an aluminium foil layer, and their combinations thereof.

[0054] In an embodiment, the second layer of radon-impermeable material of the multilayer radon-impermeable structure comprises a continuous coating layer applied over the first layer, said coating layer being configured to seal interfaces, overlaps and discontinuities of the first layer so as to enhance the overall radon impermeability of the structure.

[0055] In an embodiment, the coating of the multilayer radon-impermeable structure is selected from a list consisting of: bitumen-based coating (including bituminous emulsion or polymer-modified bitumen), polyurethane coating, epoxy coating, acrylic coating, and polymer-modified cementitious coating, and combinations thereof..

[0056] In an embodiment, the multilayer radon-impermeable structure further comprises an intermediate reinforcement layer arranged between the first radon-impermeable layer and the second radon-impermeable coating layer, the intermediate reinforcement layer being configured to mechanically stabilise the coating and to prevent crack formation and propagation.

[0057] In an embodiment, the multilayer radon-impermeable structure further comprises an intermediate reinforcement layer arranged between the first radon-impermeable layer and the second radon-impermeable coating layer, the intermediate reinforcement layer being configured to mechanically stabilise the coating and reduce crack formation.

[0058] In an embodiment, the intermediate reinforcement layer of the multilayer radon-impermeable structure comprises a fibrous mesh or scrim selected from the list consisting of: glass fibre mesh, basalt fibre mesh, polyester mesh, polypropylene mesh, aramid fibre mesh, and combinations thereof.

[0059] In an embodiment, the first layer and the second layer of the multilayer radon-impermeable structure are oriented at an angle ranging from 75° to 95° to each other, preferably from 80 to 90°, more preferably 90°, for better results.

[0060] In an embodiment, the second layer of radon-impermeable material of the multilayer radon-impermeable structure comprises a coating, for better results.

[0061] In an embodiment, the multilayer radon-impermeable structure further comprises an interstitial bonding material disposed between the first and second layers forming a gas-tight seal, for better results.

[0062] In an embodiment, the interstitial bonding material of the multilayer radon-impermeable structure is selected from a list consisting of bitumen-based adhesives, polyurethane sealants, specialty gas-tight sealants, and their combinations, for better results.

[0063] In an embodiment, the multilayer radon-impermeable structure further comprises a peripheral sealing framework that secure the assembly of the structure, for better results.

[0064] In an embodiment, the framework set of the multilayer radon-impermeable structure comprises a material selected from a list consisting of environmentally safe materials, wood, wooden battens, lignocellulosic materials, and their combinations, for better results.

[0065] In an embodiment, the multilayer radon-impermeable structure further comprises a levelling material disposed beneath the first layer to address surface irregularities, for better results.

[0066] In an embodiment, the multilayer radon-impermeable structure further comprises an intermediate reinforcement layer between the first and second layers for additional mechanical stability, for better results.

[0067] In an embodiment, the radon diffusion coefficient of the first layer of the multilayer radon-impermeable structure is less than 5 x 10 -13< m 2< / s , for better results.

[0068] The radon diffusion coefficient is the diffusion coefficient of radon gas through a material, expressed in m 2< / s. In an embodiment, the radon diffusion coefficient is determined using a two-chamber diffusion cell method. A test specimen is hermetically sealed between a radon source chamber and a receiving chamber such that radon transfer occurs exclusively through the specimen. The source chamber contains a defined radon concentration, while the receiving chamber is initially radon-free.

[0069] The radon concentration in the receiving chamber is measured over time using a radon detector, for example an ionisation-based radon monitor, preferably an AlphaGUARD monitor, optionally coupled to an air circulation device, such as an AlphaPUMP, to ensure homogeneous air mixing. The radon diffusion coefficient is calculated by fitting the measured concentration-versus-time data to a one-dimensional transient diffusion model for a planar layer, taking into account specimen thickness, exposed surface area, chamber volumes, and radioactive decay of radon-222.

[0070] It is also disclosed a building comprising the described multilayer radon-impermeable structure.

[0071] It is also disclosed a method of constructing the multilayer radon-impermeable structure, comprising the following steps: placing a framework set on a substrate layer; applying a first layer of radon-impermeable material over the framework set; positioning a second layer crosswise to the primary layer.

[0072] In an embodiment, the method further comprises the step of securing the periphery of the multilayer structure with a peripheral sealing framework, for better results.

[0073] In an embodiment, the method further comprises a step of levelling the framework set before placing the first layer between the step of placing a framework set on a substrate layer and the step of applying a first layer of radon-impermeable material over the framework set, for better results.

[0074] The general concept of this technology is illustrated in Fig. 1, where a multilayer radon-impermeable structure is shown, designed to prevent the infiltration of radon gas into buildings. This multilayer radon-impermeable structure comprises three main components: framework set (1), a first layer of radon-impermeable material (2), and a second layer (3) of radon-impermeable material.

[0075] Fig. 2 illustrates the entire multilayer radon-impermeable structure , with the framework set (1) applied to the surface in a spaced configuration, creating gaps that allow for air circulation and fluid drainage (4). These gaps facilitate the dissipation of radon gas and ensure the structure remains effective in preventing radon accumulation. This framework set (1) also allows ventilation and fluid drainage, aiding in the effective dissipation of radon gas and other fluids.

[0076] Fig. 3 depicts an embodiment of the installation of the first layer (2), which is applied directly over the framework set (1) and acts as the primary barrier against radon infiltration.

[0077] In an embodiment, the second layer (3) is applied over the first layer (2), reinforcing the seal and providing additional protection against radon infiltration. In the event of any damage to the first layer (2), the second layer (3) ensures that radon is still blocked.

[0078] In an embodiment, the cross-layer configuration of the structure, with the two layers oriented at a 90° angle to each other, as represented in Fig. 4 (ii), minimizes the risk of crack alignment, ensuring continuous protection. The structure is designed to be durable, with resistance to moisture, temperature fluctuations, and wear. The materials used are eco-friendly, contributing to the sustainability of the construction process.

[0079] The structure can be easily installed without rigid fixations, making it a flexible and cost-effective solution. It is ideal for foundations, walls, and floors in direct contact with the soil and is especially useful in areas with a high radon geological risk. The structure is suitable for both new construction and retrofit projects, providing long-term protection against radon exposure.

[0080] Subsequently, experimental results were obtained using the described architectural method in a real-world environment. Initial measurements were carried out prior to installation of the solution in a public-school building located in an area known to be affected by geological faults. After installation of the multilayer radon-impermeable structure, radon flux measurements were repeated at multiple locations, including areas corresponding to joints, which are typically considered potential linear bridges for gas migration.

[0081] At an initial stage, a radon risk map of the municipality of Oliveira do Hospital was analysed, identifying geological faults and anomalous zones associated with elevated natural radioactivity. On the basis of this analysis, and following a preliminary visual assessment, the school of Gramaços was identified as a particularly suitable site for application of the solution, as it is located directly within a geological fault and in close proximity to a radon anomaly. Nevertheless, comparative testing was carried out.

[0082] The test procedure consisted of placing four sealed collection boxes on the floor of each school building. These boxes were sealed using aluminium tape to ensure airtightness and to allow accumulation of radon gas originating from the subsoil. After sealing and closure of the valves, radon was allowed to accumulate within the boxes. Approximately one day after closure, initial radon concentration measurements were performed inside the boxes. Measurements were carried out using AlphaGUARD and AlphaPUMP equipment, connected to the boxes via certified tubing designed for radon sampling. Each measurement was performed over a period of 15 minutes per box. The recorded values demonstrated very high radon concentrations prior to installation of the solution, as indicated on Table 1. Table 1 - Values obtained from measurements carried out at the Gramagos school prior to application of the solution.BoxMeasurement timeTime (hours)Time (days)Temperature (°C)Relative Humidity (%)Atmospheric Pressure (mbar)CRn (Bq / m 3< )116:0027.51.1165694665200216:3027.91.2146294548640317:0028.41.2136594644875417:3228.91.2126794611755

[0083] In particular, at the location corresponding to box 1, an average concentration of approximately 65200 Bq / m 3< was recorded, confirming the severity of the radon flux at the site. Demonstrating effectiveness under such conditions provides confidence that the solution will perform at least as well in environments with lower radon flux through the floor.

[0084] Following installation of the anti-radon solution, a proof-of-concept phase was conducted. The positions of the measurement boxes within the school were precisely defined using a coordinate system referenced to a corner of a doorway, as illustrated in Figure 5. Radon measurements were again carried out at several locations, including at least one measurement taken directly at a joint, represented as Box 5.

[0085] The first series of measurements are indicated on Table 2. Table 2 - Values obtained from a first series measurements carried out at the Gramaços school after the application of the solution.BoxMeasurement timeTime (hours)Time (days)Temperature (°C)Relative Humidity (%)Atmospheric Pressure (mbar)CRn (Bq / m 3< )117:402.20.117.758.895811216:003.10.116.460.195895417:004.10.217.160.8958115518:002.20.116.959.795899

[0086] In a first series of measurements performed shortly after installation, radon concentrations were found to be dramatically reduced, with recorded values ranging from approximately 11 Bq / m 3< to 115 Bq / m 3< , including at the joint location. Table 3 - Values obtained from a second series measurements carried out at the Gramaços school after the application of the solution.BoxMeasurement timeTime (hours)Time (days)Temperature (°C)Relative Humidity (%)Atmospheric Pressure (mbar)CRn (Bq / m 3< )116:3821.00.92942956620217:0021.30.92643956465417:2121.70.92544956387517:4222.00.92452956217

[0087] A second series of measurements, performed after a longer accumulation period, also showed significantly reduced radon concentrations, with values remaining well below those measured prior to installation and within ranges compatible with applicable reference levels.

[0088] In final conclusion, the anti-radon solution demonstrated, under real and highly demanding conditions, an average radon concentration reduction ranging from approximately 95.7% to 98.7%. Importantly, this high level of effectiveness was also observed in joint areas corresponding to potential linear bridges, confirming the robustness and continuity of the protective mechanism. These results validate the solution as an effective architectural and construction-based approach for mitigating radon ingress in buildings located in high-risk geological areas.

[0089] The term "comprising" whenever used in this document is intended to indicate the presence of stated features, integers, steps, components, but not to preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0090] The disclosure should not be seen in any way restricted to the embodiments described and a person with ordinary skill in the art will foresee many possibilities to modifications thereof. The above-described embodiments are combinable.

[0091] The following dependent claims further set out particular embodiments of the disclosure.

Claims

1. A multilayer radon-impermeable structure for building construction applications comprising: a framework set (1) applied over a substrate layer, the framework set comprising spaced structural elements configured to define lateral channels oriented towards an exterior boundary of the building; a first layer of radon-impermeable material applied directly over the framework set, the first layer of radon-impermeable material having a radon diffusion coefficient of less than 5 × 10-13 m2 / s; a second layer of radon-impermeable material applied over the first layer of radon-impermeable material, wherein the second layer of radon-impermeable material is applied in a crosswise orientation relative to the first layer; wherein the first and second layers extend outwardly from the framework set by at least 10 mm, and are configured to extend from the framework set into an adjacent building structure, thereby forming a continuous peripheral sealing framework preventing radon migration at floor-wall interfaces.

2. The multilayer radon-impermeable structure according to the previous claim, wherein the first layer and the second layer are oriented at an angle ranging from 75° to 95° to each other, preferably from 80 to 90°, more preferably 90°.

3. The multilayer radon-impermeable structure according to any of the previous claims, wherein at least one of the first layer of radon-impermeable material and the second layer of radon-impermeable material comprises a polymeric membrane or panel selected from the list consisting of: high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), polypropylene (PP), polyvinyl chloride (PVC), thermoplastic polyolefin (TPO), ethylene propylene diene monomer (EPDM), butyl rubber, ethylene vinyl alcohol (EVOH) barrier film, and composites comprising a metallised layer and / or an aluminium foil layer, and their combinations thereof.

4. The multilayer radon-impermeable structure according to any of the previous claims, wherein the second layer of radon-impermeable material comprises a continuous coating layer applied over the first layer, said coating layer being configured to seal interfaces, overlaps and discontinuities of the first layer so as to enhance the overall radon impermeability of the structure.

5. The multilayer radon-impermeable structure according to claim 4, wherein the coating is selected from a list consisting of: bitumen-based coating, including bituminous emulsion or polymer-modified bitumen, polyurethane coating, epoxy coating, acrylic coating, and polymer-modified cementitious coating, and combinations thereof..

6. The multilayer radon-impermeable structure according to any of the previous claims, further comprising an intermediate reinforcement layer arranged between the first radon-impermeable layer and the second radon-impermeable coating layer, the intermediate reinforcement layer being configured to mechanically stabilise the coating and to prevent crack formation and propagation.

7. The multilayer radon-impermeable structure according to any of the previous claims, further comprising an intermediate reinforcement layer arranged between the first radon-impermeable layer and the second radon-impermeable coating layer, the intermediate reinforcement layer being configured to mechanically stabilise the coating and reduce crack formation.

8. The multilayer radon-impermeable structure according to claim 6, wherein the intermediate reinforcement layer comprises a fibrous mesh or scrim selected from the list consisting of: glass fibre mesh, basalt fibre mesh, polyester mesh, polypropylene mesh, aramid fibre mesh, and combinations thereof.

9. The multilayer radon-impermeable structure according to the previous claim, wherein the interstitial bonding material is selected from a list consisting of bitumen-based adhesives, polyurethane sealants, specialty gas-tight sealants, and combinations thereof.

10. The multilayer radon-impermeable structure according to any of the previous claims, wherein the framework set is configured to support loads of at least 400 kg / m2.

11. The multilayer radon-impermeable structure according to any of the previous claims, wherein the framework set comprises a material selected from a list consisting of wood, wooden battens, lignocellulosic materials, and their combinations thereof, further comprising a peripheral sealing framework formed by recesses and / or grooves provided in adjacent wall portions, the recesses and / or grooves having a depth of at least 10 mm, configured to receive edge portions of the first and second layers such that a continuous radon-impermeable barrier is formed at floor-wall interfaces.

12. The multilayer radon-impermeable structure according to any of the previous claims, further comprising a levelling material disposed beneath the first layer to address surface irregularities.

13. The multilayer radon-impermeable structure according to any of the previous claims, further comprising an intermediate reinforcement layer between the first and second layers for additional mechanical stability.

14. The multilayer radon-impermeable structure according to any of the previous claims, wherein the framework set comprises wooden battens arranged with spacing sufficient to define continuous lateral channels, and wherein the first radon-impermeable layer comprises large-format panels having a surface area of at least 6 m2.

15. A building comprising the multilayer radon-impermeable structure described in any of the previous claims.

16. A method of constructing the multilayer radon-impermeable structure described in any of the previous claims 1 to 11, comprising the following steps: placing a framework set on a substrate layer; applying a first layer of radon-impermeable material over the framework set; positioning a second layer crosswise to the primary layer.

17. The method according to any of the previous claims 12 to 13, further comprising a step of levelling the framework set before placing the first layer between the step of placing a framework set on a substrate layer and the step of applying a first layer of radon-impermeable material over the framework set.

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