Durability of the Building Airtightness
Chair(s): Valerie Leprince (cerema, France), Andres Litvak (cerema)
Air leakages increasingly affect the energy performance of new buildings. Since the early 2000s, many countries have introduced regulations that emphasize airtightness, including mandatory standards, aligning with Europe’s goal of achieving nearly zero energy buildings by 2030. However, building airtightness requirements are only effective if the levels remain durable over time. Studies reveal that these mandates often lead to last-minute sealing efforts, compromising durability.
The long-term durability of airtightness products and assemblies remains a complex issue, involving:
• Modeling the mechanical behavior and deformations of buildings and products,
• Laboratory-based accelerated aging tests,
• Field measurements for performance characterization.
Recent studies have explored this through two primary approaches: analyzing real-building measurements to assess airtightness over time and conducting laboratory tests to simulate the accelerated aging of sealing products. This session will present insights from these approaches, including findings from the Durabilit’air 2 project, which focuses on understanding the long-term durability of airtightness in buildings.
Presentations of the Workshop
State Of The Art Of Knowledge On Building Airtightness Durability
Valerie Leprince, Nolwenn Hurel
cerema
Significant progress has been made in improving the airtightness of new buildings. However, the durability of this airtightness over time remains insufficiently understood, and the consequences of its potential degradation are largely undocumented. This presentation provides an overview of existing research on the durability of building airtightness. Field studies suggest that airtightness tends to decrease during the first years of a building’s life before stabilizing, though the underlying causes of these changes are rarely analyzed in depth. Several factors that may influence these variations have been identified. In parallel, laboratory ageing studies reveal a lack of standardized protocols to assess the long-term airtightness performance of product assemblies. This review has served as both a foundation and a key motivation for the subsequent study that will be presented.
Understanding Early Airtightness Variations: Lessons from 10 Residential Case Studies
Sylvain Berthault1, Bassam Moujalled1, Valerie Leprince1, Andres Litvak1, Florent Tivolle2, Nolwenn Hurel1
1cerema, 2cetii
This presentation explores the early evolution of building airtightness through the in-depth monitoring of 10 newly built houses. The construction process was closely followed, with on-site observations focused on the implementation conditions of the airtightness layer. A specific protocol was developed to assess environmental parameters such as indoor surfaces dust levels, temperature, and humidity during installation. Airtightness was measured at commissioning and then repeatedly tested 4 to 5 times during the first year of occupancy.
The results reveal significant insights: in several cases, an increase in air permeability occurred after the first heating period. This effect was particularly noticeable in houses where the airtightness layer was applied late in the construction process, using mastic on plasterboard rather than an airtight layer on masonry. These findings highlight the importance of both timing and substrate conditions in ensuring the durability of airtightness. The study contributes to a better understanding of how early implementation method dans choices can influence long-term airtightness performance.
From Site to Lab: Evaluating Implementation Conditions and reproducing them in laboratory
Andres Litvak, Eddy Handschoewercker, Sylvain Berthault
cerema
International standards emphasize that surfaces must be clean, dry, stable, and free from dust to ensure the effective adhesion of airtightness products. Yet, no manufacturer currently guarantees adhesion on dusty surfaces, identifying dust—alongside temperature and humidity—as a key limiting factor for performance over time.
This study focuses on dust contamination and its potential role in degrading the long-term airtightness of building envelopes. Specifically, we explored and discussed the feasibility of experimentally quantifying dusting of surface at construction sites before the application of airtightness products.
Three dust quantification methods were reviewed: laser granulometry (light diffraction), visual contrast (based on the NF X 50-792 standard), and weight measurement using adhesive tape sampling. The latter method was selected for its practicality and was used to develop an operational on-site protocol. Dust was sampled at the dustiest stages of construction, and tape samples were weighed using a high-precision balance.
Seventeen samples from various sites were analyzed. Floor surfaces consistently showed measurable dust quantities, while vertical surfaces yielded low dust masses with uncertainties often exceeding the measured values. These results appear to be consistent with measurements made in the laboratory. These findings confirm that the weighing method is suitable for horizontal surfaces but less reliable for vertical ones, where adjustments—such as larger sample areas—may be needed.
In conclusion, this protocol offers a promising tool for quantifying dust accumulation on construction sites, particularly on floors. It may serve as a foundation for future research into how surface contamination contributes to the degradation of airtightness performance over time.
Experimental Measurement Results Of The Impact Of Surfaces Sust Built-up And Temperature On Building Airtightness Durability
Andres Litvak1, Eddy Handschoewercker1, Alexis Flamand2, Fabrice Bonnaudin2
1cerema, 2APPLUS RESCOLL
To better understand how on-site implementation conditions influence the long-term performance of airtightness solutions, a laboratory protocol was developed to replicate real-world levels of dust and temperature during implementation of airtightness products assemblies. Three typical airtightness junction configurations were tested: (1) PVC/mastic/plasterboard, (2) wood/mastic/plasterboard, and (3) airtightness membrane/adhesive/wood.
Each configuration was applied under three conditions: normal, cold, and dusty. Initial airtightness was measured after implementation, followed by an accelerated aging process, and a second airtightness test.
The results reveal important trends. Assemblies involving mastic on PVC material exhibited greater degradation over time than membrane-and-adhesive systems, with air permeability doubling after aging—and tripling when applied in cold conditions. Interestingly, mastic-based joints showed similar initial airtightness regardless even when implemented in dusty conditions. While, for membrane/adhesive assemblies, poor implementation conditions had a strong initial impact. Cold application doubled initial permeability, while dusty conditions led to a dramatic 90-fold increase. Furthermore, cold-applied membrane/adhesive joints degraded significantly with aging, while those applied under normal conditions remained stable.
Finally, we discussed these laboratory results on the impact on airtightness durabilitay of the dusting of surfaces with the results obtained through a field measurement campaign on construction sites.
These findings underscore the critical role of environmental conditions during installation, and the need for careful control on-site to ensure the durability of airtightness over time.
