A house project, whether it involves new construction or renovation, relies on a sequence of technical and financial decisions where the order is as important as the content. Each poorly calibrated step – a rushed soil study, an underestimated budget, an unrealistic timeline – impacts the following ones and increases the final bill. Understanding this sequential logic helps avoid the most costly mistakes.
Real cost of high-performance renovation in 2024: significant price increases
Before estimating a project, one must consider a recent reality. According to a study by the Institute for Climate Economics (I4CE) published in September 2026, the average price of a high-performance renovation has risen from €556 to €878 excluding tax per square meter between 2019 and 2024, representing a 58% increase. This inflation affects both materials and skilled labor.
This data changes the game for any homeowner who is hesitating between renovating in stages, undertaking a comprehensive renovation, or considering partial reconstruction. Comparing several costed scenarios before signing a quote becomes a full-fledged framing step, not just a simple precautionary reflex.
To delve into each expense item and explore concrete feedback, the articles on the Maison Info website detail the budgetary trade-offs faced by individuals in 2026.
MaPrimeRénov’ after September 2026: eligible works and exclusions
Decree No. 2026-822 of August 25, 2026, has significantly revised the “gesture-based” pathway of MaPrimeRénov’. Several common work items have been removed from the list of fundable expenses in mainland France.
Works excluded from the gesture-based pathway
- Insulation (walls, attics, floors) and ventilation are no longer funded in this pathway, which requires switching to the “extensive renovation” pathway to obtain assistance for these items.
- Wood or biomass heating equipment, thermodynamic water heaters, and solar thermal equipment in mainland France have also been removed.
- For a single-family home, assisted works must no longer lead to the installation or retention of a fossil heating system, which effectively excludes gas or oil boilers from the subsidized scope.
What remains fundable
Some heat pumps, connection to a heat network, removal of an oil tank, and, under certain conditions, energy audits remain eligible. Checking the exact list before starting work avoids discovering afterward that a planned item does not qualify for any assistance.
The distinction between the “gesture-based” pathway and the “extensive renovation” pathway determines the amount and nature of the aid. Choosing the wrong pathway can reduce public funding by several thousand euros.
Soil study and site constraints: the technical foundation of the project
Competitors often mention orientation and brightness. A less visible but equally structuring point concerns the nature of the soil. A geotechnical study (G2 study in the pre-project phase) identifies risks of expansive clay, high groundwater, or unstable fill.
Without this study, the choice of foundations relies on assumptions. Undersized foundations on clay soil can cause structural cracks within a few years. The additional cost of a soil study represents a tiny fraction of the overall budget, while the cost of foundation repairs after damage can reach a significant percentage of the total construction cost.
The soil study determines the type of foundations, thus the actual budget for the structural work. Any construction quote that does not mention the nature of the soil is based on a fragile estimate.
Planning the sequence of work to avoid rework
A house project follows a strict technical order. Ignoring this sequence generates costly rework: laying a floor covering before finishing the second work exposes it to damage, installing plumbing after partitioning requires opening and then closing the partitions.
The basic logic follows this progression:
- The structural work (foundations, load-bearing walls, framework, roofing) must be completed and waterproof before any interior intervention.
- The second work (insulation, partitions, electrical and plumbing networks) follows once the building is airtight.
- Finishes (painting, coverings, interior joinery) come last, when all networks are tested and the coatings are dry.
Each trade intervenes within a precise window. A schedule that does not allow for buffer time between trades accumulates cascading delays. Planning two to three weeks of buffer between each major phase absorbs unforeseen events without delaying the delivery date.
Acceptance of work: the transfer of responsibility
Acceptance is the legal act by which the project owner accepts the completed work. It is from this date that the ten-year warranty begins (Article 1792-6 of the Civil Code). Any visible defect not noted in the acceptance report becomes difficult to assert later.
Three points deserve special attention during this stage: verifying the conformity of the work with the contractual description, noting all reservations (even minor ones) in the report, and only signing the lifting of reservations after effective correction. A rushed acceptance transfers the risk to the owner without covering the defects.
The best-budgeted and best-designed house project often hinges on these last administrative details. The rigor applied to the foundations must extend to the signing of the last document.
