Construction project management in Onex
Planning building work? Apartment, house or building renovation, a new storey or a roof extension, running the project is our job.
HMG Construction Management SA manages building work in Onex, where the firm already has a completed project. It takes charge of the plans, the permit application filed as a registered MPQ agent, the costing, the choice of contractors and the running of the site to SIA standards, with one point of contact for you.
What kind of work in Onex?
Onex became a municipality in 1851 and lies on the left bank, between the Rhône and the Arve. It is small in area and large in population. The OCSTAT profile for Onex gives 19,141 residents at the end of 2025 on 281 hectares, hence 6,805 people per square kilometre.
That density hides something the cantonal table of buildings brings out. Of 1,321 residential buildings at 31 December 2025, 829 are single-family houses, more than six in ten. The 492 multi-dwelling buildings account for much of that density, yet by number of buildings the house remains the most common case.
The stock is not very old. 147 buildings predate 1946, about one in nine, and 292 were built after 2000. Two thirds therefore went up between those dates. These are houses and blocks whose kitchens, bathrooms, windows and services are reaching replacement age, and where owners frequently look for more floor area.
Local information is available on the Onex municipal website (in French).
Permits in Geneva
When extending a house or adding a floor, the question is which procedure applies. The cantonal page on permit types reserves the fast-track procedure, known as APA, for interior changes and for building in the fifth zone without a derogation, among other cases. If it is unclear what the plot allows, a preliminary application, or DP (demande préalable), obtains the authority's answer on siting, envelope and volume.
These procedures are described in our guide to building permits and procedures in Geneva.
Types of work in Onex
- House renovation, the most frequent case with 829 single-family houses.
- House extension, to gain a room at ground level.
- Adding a storey, when the plot leaves no room on the ground.
- Apartment renovation, in the 492 buildings with several dwellings.
- Kitchen renovation, a regular job in buildings from before 2000.
How HMG manages your project in Onex
The first option is for HMG to handle everything, from the first sketch to acceptance of the works, filing the permit application as an agent registered on the Geneva MPQ list (mandataires professionnellement qualifiés, the cantonal register of qualified building professionals). The second is that you work with an architect, who designs the scheme and obtains the permit, and HMG then manages construction at their side.
For a house that stays occupied during the works, the firm splits the job into phases so that the family keeps a usable kitchen and bathroom. It prepares an overall estimate by trade, consults several contractors for each, gives you a comparison and a programme, then follows the work and the payments week by week.
Municipalities in the same sector
Project management is offered in the same way in the municipalities of the sector.
Projects by HMG in Onex
Frequently asked questions
Is Onex mainly apartment buildings or houses?
By number of buildings, houses dominate. OCSTAT counts 829 single-family houses among 1,321 residential buildings, while density reaches 6,805 people per square kilometre.
Can you add a floor to a house in Onex?
It depends on the plot and the building rules that apply to it. A preliminary application obtains the authority's position on envelope and volume before full drawings are commissioned.
Can we stay in the house during the works?
Often yes, if the job is organised in phases. The firm writes this into the programme at tender stage so that contractors allow for it in their prices.
Related guides and pages
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