A construction or home renovation project is largely determined before the first blow of the hammer. The technical choices made during the design phase, the sequencing of trades, and regulatory compliance condition the final cost much more than the choice of tiles or paint.
Ban on gas boilers and impact on the thermal lot in renovation
Since the implementing decree of April 3, 2024, of law n°2023-175 of March 10, 2023, the installation of new gas boilers is gradually prohibited. In renovations, this constraint disrupts the sizing of the thermal lot: air-water heat pumps, biomass boilers, or hybrid systems now replace gas in most projects.
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We are observing a temporary shortage of qualified labor in thermodynamic plumbing on the ground. The direct consequence: installation delays are increasing, and quotes are rising. Anticipating the choice of heating system from the preliminary project allows for reserving a certified installer several months in advance and adapting the existing hydraulic network without costly modifications.
For houses built before the 1980s, switching from a gas boiler to a heat pump often requires strengthening thermal insulation. Without this step, the efficiency of the heat pump drops, and the energy bill remains high.
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We recommend systematically coupling the replacement of the generator with an independent energy audit, which identifies the priority losses to address. For more information about Pôle Conseil Habitat, the platform centralizes construction and renovation sectors with support tailored to each technical configuration.
Building permit timelines: dense urban areas vs. rural digital counter
The processing of urban planning permits shows major territorial disparities. According to the economic note from the DHUP (Direction of Housing, Urban Planning, and Landscapes) from February 2026, the timelines for obtaining building permits for major renovations have skyrocketed in dense urban areas since 2025. The overload of municipal processing services extends procedures well beyond the theoretical regulatory timelines.
In rural areas, the digital single window accelerates the processing of files. The gap between the two contexts can represent several months of delay on a construction site.
Adapting the project schedule to the territory
A project owner planning an extension or elevation in the city center must submit their file as early as possible, ideally even before finalizing the execution plans. In rural areas, the submission can fit into a tighter schedule without compromising the start date of the construction site.
The common mistake is to launch the consultation of companies before obtaining the permit cleared of any appeals. In case of refusal or modification imposed by the architect of the buildings of France, the signed quotes become void, and the deposits paid are rarely recoverable.
Independent diagnostics before work: avoiding repairs on damp structures
Post-flood experience from 2024 shows an increase in disputes related to defects in wet renovations. Companies intervene on walls still laden with residual moisture, install linings or coatings that trap water, and issues appear a few months later.
An independent diagnostic before work protects against costly repairs. This diagnostic is not limited to the energy performance diagnosis (DPE): it includes a hygrometric measurement of the walls, an analysis of capillary rise, and, if necessary, a structural survey. The decree of July 26, 2024, amending decree n°2021-19 of January 11, 2021, has also strengthened the requirements of the DPE, but it remains insufficient to characterize the state of an old structure exposed to water damage.
- Hygrometric measurement of load-bearing walls and ground floors before any insulation intervention
- Search for capillary rise through test injection or passive electro-osmosis, depending on the nature of the foundation
- Verification of the condition of buried networks (drainage, peripheral drainage) to rule out external water input
- Analysis of existing ventilation: a renovated damp structure without suitable mechanical ventilation develops mold in less than a year
Sequencing of trades and site coordination in new construction
The order of intervention of trades determines the final quality of the work. In new construction, the classic sequencing (structural work, framework-roofing, exterior carpentry, then finishing work) seems obvious. In practice, delays concentrate on the interfaces between trades.
The passage of electrical conduits and plumbing networks must be validated before the closure of partitions. A lack of coordination at this stage generates chases in new walls, unplanned thermal bridges, and additional costs for corrections.
Role of the project manager in managing interfaces
We recommend entrusting coordination to an independent project manager, distinct from the builder. Their role is not limited to schedule monitoring: they validate reservations in the slabs, check the compliance of ceiling heights before installing false ceilings, and verify drainage slopes before pouring screeds.
Without this supervision, non-conformities are discovered at reception, when corrections are most costly. The reception report with reservations remains the last contractual lever for the project owner, but it comes too late to avoid technical compromises.
- Plan a weekly site meeting with all trades present on site
- Require an execution detail book validated by the project manager before each change of trade
- Systematically photograph embedded networks before closing walls, to create a usable executed works file
The success of a construction or renovation project relies on decisions made upstream: choosing a thermal system compliant with current regulations, early submission of the permit adapted to the territorial context, structural diagnostics before any intervention on old structures, and rigorous coordination of trades by an independent project manager. It is these technical choices, rarely visible in the final result, that separate a well-managed site from a financial pitfall.