A sloping plot, clay soil identified at the neighbor’s, a lot facing west in an area where summers regularly exceed comfort thresholds: every house construction project starts with a local constraint that cannot be ignored. Before discussing plans or financing, it is the land and its regulatory context that dictate the actual feasibility of the real estate project.
Soil study and land constraints before any decision
We still see buyers signing a preliminary agreement on a plot without having ordered a geotechnical study. A simple glance at the cracked facades in the neighborhood can betray clay or damp soil, but only a formal soil study allows for the proper sizing of foundations.
On a subdivided plot, the infrastructure (connections for water, electricity, sanitation) is often already resolved. In scattered development, it is an item to budget from the start, as infrastructure costs can alter the financial balance of the project.
Before signing, one also checks the urban planning certificate. This document indicates the applicable rules for the plot: maximum height, footprint, setbacks from boundaries. It directly conditions the shape and size of the house that can be built there. Plans come after, not before, because we design a house for a plot, not the other way around.
To compare already completed projects and refine construction choices, one can rely on the Bien Construire! website, which gathers house configurations suited to different contexts.
RE2020 and summer comfort: what the regulations impose from the design stage
RE2020 is not just an energy label. Since 2025, the carbon thresholds applicable to the construction of individual houses have tightened, and a new level is planned for 2028. The choice of construction system, materials, and heating method must therefore be made from the design phase, not during the construction process.
Summer comfort has become a central regulatory criterion. RE2020 requires limiting summer overheating without systematically resorting to air conditioning. In practice, this means working on the orientation of openings, planning for solar protections (sunshades, roof overhangs), and choosing materials with high thermal inertia.
A point often overlooked: since 2026, the Ministry of City and Housing has made public the data from the RE2020 Observatory for completed individual houses. This data allows for comparison of the performances actually declared by builders, beyond commercial promises. Consulting this data before signing a contract provides an objective benchmark.
Biosourced materials and carbon footprint
Wood, cellulose wadding, or hemp help reduce the carbon footprint of construction. RE2020 clearly pushes towards these biosourced materials, but not all builders master them equally. Feedback varies on this point: some wood projects proceed smoothly, while others suffer from air tightness issues if the vapor barrier or vapor retarder is poorly installed.
Asking the builder for their references on similar houses (same construction system, same climatic zone) remains the best filter.
Construction budget: underestimated items
The budget for a new house is not limited to the price per square meter quoted by the builder. Several items are added and can represent a significant portion of the overall envelope:
- The soil study and any special foundations (piles, slab) if the land is unstable or sloping.
- The mandatory damage insurance, taken out before the start of construction, which covers issues under the ten-year guarantee.
- The connection fees to networks in scattered development, and the development taxes set by the municipality.
- The exterior improvements (fencing, access, paving) rarely included in the construction contract.
A realistic financing plan includes these items from the start. Asking the builder for these line by line, before signing the individual house construction contract (CCMI), avoids unpleasant surprises halfway through the project.
Site monitoring and acceptance: protecting your interests until the handover of keys
The new construction market remains tense. Housing permits have remained below the average of the previous five years in recent times, which can affect the availability of craftsmen and extend deadlines.
Participating in site meetings is not a formality. It is the time to check that the delivered materials match the contractual description and that the work complies with the approved plans. Photographing each stage of the site serves as evidence in case of disputes.
Acceptance and reservations
On the day of acceptance, each room and each piece of equipment is inspected. Any anomaly found must be recorded in the acceptance report as a reservation. Without a written reservation, it becomes much more difficult to obtain a remedy.
There is then a period to report defects not visible on the day of acceptance. The perfect completion guarantee covers the first year. The ten-year guarantee protects against defects affecting the solidity of the work or rendering it unfit for its intended use for ten years.
- Check the operation of each opening, each outlet, each faucet on the day of acceptance.
- Test the heating and ventilation system, even in summer.
- Keep all documents: RE2020 certificate, report, equipment manuals, insurer contact details.
Building your house remains a project of several months where every decision made upstream – land, materials, contract – conditions the future. The safest way to avoid unpleasant surprises is to validate nothing without having read, compared, and verified on the ground.
