The environmental regulation RE2020, geotechnical constraints, and the volatility of construction costs are radically changing the way a new home project is prepared. Building your house based on the right technical diagnosis, even before considering the plans, avoids the additional costs that we regularly observe on poorly anticipated sites.
Geotechnical study and soil constraints: the true starting point of a construction project
A construction project begins with the soil, not with the plan. The G2 AVP (pre-project) geotechnical study determines the nature of the land, its bearing capacity, the depth of good soil, and the level of the water table. This data conditions the type of foundations (strip footings, slab, piles) and thus a significant part of the structural budget.
On clayey land subject to shrink-swell, the foundations must extend beyond the drying zone. Ignoring this parameter exposes one to structural cracks within a few years. A simple glance at neighboring houses can reveal disorders, but only the geotechnical report provides a reliable answer.
We recommend ordering the soil study before signing the land purchase agreement, inserting a suspensive condition related to the results. This precaution allows one to withdraw from a plot of land whose foundation treatment would blow the budget. The projects referenced on the website www.bien-construire.ch illustrate this logic of prior verification applied to different types of land.
RE2020 and summer comfort: what the regulation imposes on house plans
RE2020 is not limited to energy performance. It incorporates an indicator of summer comfort measured in degree-hours of discomfort, which profoundly changes the design from the planning stage. Orientation of the windows, fixed solar protections (overhangs, sunshades), thermal inertia of structural materials: these choices are no longer optional; they condition regulatory compliance.
The application data for RE2020 is now public, according to the Ministry of City and Housing (September 2026). It allows for comparing the actual performances observed on newly delivered homes. Before validating a builder, we advise asking for the RE2020 results of their latest deliveries, not just the forecast simulations.
Bio-based materials and carbon footprint
RE2020 introduces a maximum threshold for greenhouse gas emissions over the building’s life cycle. This threshold tightens in stages. Wood, cellulose wadding, or raw earth brick show a lower carbon footprint than traditional concrete, making them mechanically easier to integrate into a compliant project.
The choice of materials directly influences the carbon compliance of the project. A builder who still systematically offers concrete blocks without thermal or carbon justification deserves a direct question about their calculation method.
Construction budget: items that quotes do not detail
The price announced by a builder rarely covers the total actual cost of a house. Several items remain outside the individual house construction contract (CCMI) and significantly increase the final bill.
- Site development work (connections to water, electricity, sanitation networks) varies greatly depending on the distance to existing networks and the configuration of the land
- The geotechnical study, boundary marking by a surveyor, and notary fees related to the land acquisition are never included in the construction quote
- External developments (fencing, vehicle access, landscaping) represent an often underestimated item at signing
- The contractual revision of prices during construction, allowed by most CCMIs via an index BT01, can push the final amount higher if the work extends
In a context where construction costs remain volatile, comparing quotes based solely on the initial price is a common mistake. One must examine the conditions for price revision, the contractual delivery deadlines, and the financial health of the builder. A company in cash flow difficulty generates delays on site that, in turn, activate the revision clauses.
Environmental rules of the land: checks before purchase
The environmental constraints surrounding the land have strengthened. The unique regime for hedges, for example, now regulates the uprooting and cutting of hedges on agricultural and peri-urban plots. A plot bordered by protected hedges may impose construction setbacks or prohibit certain placements.
The Local Urban Plan (PLU) remains the first source to consult, but it is also necessary to check public utility easements, protection zones for water catchments, and inventoried wetlands. A buildable plot according to the PLU may be subject to environmental restrictions that complicate or increase the cost of the project.
Building permit and compliance
The submission of the building permit occurs after finalizing the plans and choosing the construction method. The standard processing time is two months for an individual house, but it extends if the land is located in a protected area (historical monument, classified site). Anticipating these delays in the project’s timeline avoids blocking a bank financing whose loan offer has a limited validity period.
The choice of land, RE2020 compliance, budget solidity, and environmental constraints form a technical foundation to secure before discussing aesthetics or interior layout. A well-prepared construction project is played out in the months leading up to the first shovel, not during the construction phase.
