Onex: a built heritage affected by asbestos
Onex is emblematic of the Genevan new town model of the 1960s. Conceived as an autonomous satellite town to the west of Geneva, it was built in a very short time to respond to the post-war demographic pressure. In the space of approximately fifteen years, between 1960 and 1975, Onex saw dozens of collective buildings, schools, sports facilities and shopping centres erected, which still constitute the bulk of the municipal built fabric today.
This construction timeline concentrated on the 1960–1975 period places Onex at the heart of the phase of greatest asbestos use in Swiss construction. Buildings from this period systematically incorporated asbestos-based materials — this was not an exception but the norm. Rental buildings in the Cité d’Onex and Les Bossons, often constructed within public utility housing programmes, followed the standards and specifications in force, which included asbestos without restriction.
The municipality has since transformed with densification and renovation projects. The Grandes-Communes district and the sectors near the Route de Chancy have seen rehabilitation operations, but a significant proportion of the original building stock has not yet undergone complete renovation.
Which buildings are concerned in Onex?
Almost all the Onex building stock constructed before 1991 is potentially affected. Three typologies stand out.
Residential buildings
The Cité d’Onex and the Les Bossons district concentrate towers and housing slabs constructed between 1960 and 1975 — the historical core of the asbestos issue in Onex. Vinyl-asbestos floor tiles in apartments and circulation areas, fibre cement facades, sprayed coatings in underground car parks, asbestos-cement ventilation ducts, lagging on riser columns: this configuration is systematic in these buildings.
More recent developments from the 1975–1985 period, although constructed after the peak of use, may contain asbestos-containing smoothing renders and jointing products.
Commercial and administrative buildings
Collective facilities in the estate — school complexes, sports installations, shopping centres — constructed in the 1960s–1970s present at-risk configurations: sprayed coatings in large halls, fibre cement suspended ceilings, vinyl floors over large surfaces.
Villas and single-family houses
Sectors on the outskirts of the municipality towards Bernex and Confignon include a few villas from the 1960s–1980s. Fibre cement roofing or annexes, tile adhesives, cellar or garage floor tiles: these materials must be investigated before any transformation project.
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Common asbestos-containing materials in Onex
The Onex building stock from the 1960–1975 period presents a palette of characteristic asbestos-containing materials:
- Vinyl-asbestos floor tiles in kitchens, bathrooms and corridors of almost all apartments predating 1975
- Black or brownish laying adhesives, also asbestos-containing
- Spandrel panels, brise-soleil and balcony cladding in fibre cement sheets
- Bituminous flat roof waterproofing membranes (certain asbestos-containing formulations)
- Sprayed coatings in underground car parks, cellars and technical rooms
- Lagging on riser columns and heating pipework
- Asbestos-cement ventilation ducts
- Pipe penetration sealing products
- Tyrolean or textured render finishes (1965–1975 period)
Collective boiler rooms and cellars in large towers often concentrate the most degraded and most urgently identifiable materials.
Regulations applicable in Onex
Onex is in the canton of Geneva, subject to the obligation of prior investigation before any construction site likely to disturb materials in a building predating 1991, even without a building permit. Given the concentration of buildings from the 1960s–1975 period in Onex, practically every renovation project triggers this obligation.
For projects subject to permit, the diagnostic report must be attached to the OAC file and prepared by a FACH expert. Condominiums and property agencies managing buildings from the 1960s–1970s are well advised to carry out a comprehensive diagnosis of their property portfolio rather than ordering successive partial diagnoses — this approach is more economical and allows interventions to be planned with full knowledge of the situation.
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Frequently asked questions about asbestos diagnosis in Onex
Onex built extensively in the 1960s. Can it be said that a building from that period necessarily contains asbestos?
It is very probable that a building constructed between 1960 and 1975 in Onex contains asbestos in at least some of its materials. However, only a diagnosis with laboratory analyses can confirm this. There are also buildings from this period that have undergone complete renovation including decontamination. The diagnosis allows a precise assessment of the actual situation of each building.
My apartment has ceilings with a particular texture. Could it be an asbestos-containing sprayed render?
Tyrolean or textured render finishes applied in the 1960s–1975 period may contain asbestos. A sample and laboratory analysis are necessary to confirm this. If so, these materials generally present no risk in their current state, but any intervention (sanding, drilling, removal) must be carried out with appropriate precautions.
The energy renovation of my building in Onex is subsidised. Is the asbestos diagnosis eligible for support?
Asbestos diagnosis is generally not included in Genevan cantonal subsidy programmes for energy renovation. However, since it is a legal precondition for carrying out the works, it is often accepted as a justifiable preliminary cost in subsidy files. Check with your cantonal energy service.
Our Onex condominium is planning a complete renovation over 3 years. How should the diagnoses be organised?
For a phased renovation, a comprehensive diagnosis carried out in advance is the most efficient solution. This single diagnosis covers the entire building, identifies all asbestos-containing materials and their locations, and provides a working basis for the companies that will intervene in each phase. It is significantly more economical than ordering a new diagnosis for each construction phase.
My apartment was already renovated in 1998. Is it still affected by asbestos?
If the 1998 renovation replaced all suspect materials (floor tiles, suspended ceilings, partitions), the renovated zones no longer present a risk. However, zones not touched by that renovation remain potentially asbestos-containing. A diagnosis allows a precise assessment of what remains.
Who should be contacted in the event of a friable sprayed coating discovered during unforeseen works?
In the event of an incidental discovery of suspect friable materials during works, the works must be immediately stopped in the zone concerned. A FACH expert must be contacted urgently for a rapid assessment. In Geneva, the OCIRT (cantonal labour inspection office) can be approached in situations presenting an immediate danger to workers.