The choice of heating system now determines the entire renovation project. Since September 1, 2026, the rules of MaPrimeRénov’ require the decarbonization of heating and domestic hot water to access the “major renovation” pathway. This change disrupts the technical order of the work: fixing the heating method before sizing the insulation has become a non-negotiable prerequisite for any subsidized project.
Technical sequencing of the work: heating dictates insulation
A renovation project is no longer planned from the roof to the ground floor. The choice of heat generator determines insulation needs, not the other way around. Installing an air-water heat pump before addressing the walls alters the required power, the sizing of the hydraulic network, and the positioning of the outdoor unit.
We recommend completing the thermal study with the target heating system integrated into the calculation. A serious engineering firm will refuse to fix the thicknesses of insulation until the heat source is finalized. Any reversal of this sequence exposes one to oversizing or, worse, to underperformance of the envelope, which forces redoing already completed tasks.
To delve deeper into each technical aspect, Bobo Le Brico’s guides detail the steps by trade with a level of precision rarely achieved on generalist sites.
MaPrimeRénov’ since September 2026: what remains fundable by action
The “by action” pathway has refocused on a few specific operations. Certain heat pumps, connection to a heating network, removal of an oil tank, and the energy audit associated with other work are still eligible. Insulation alone, ventilation alone, or a wood stove installed without further intervention no longer qualify for MaPrimeRénov’ as an isolated action.
This restriction has a direct consequence on financial structuring: a homeowner who intended to insulate their attic and then, the following year, replace their boiler loses the benefit of aid on the first lot. Combining tasks into a single major renovation file becomes the most cost-effective strategy.
France Rénov’ now centralizes requests for MaPrimeRénov’, MaPrimeAdapt’, and Ma Prime Logement Décent since August 17, 2026. Any administrative process must be initiated before the start of the project, or eligibility will be lost.
Decarbonization constraint on major projects
Major renovation projects can no longer retain or install gas or oil heating under conditions that qualify for aid. This rule, effective since September 1, 2026, requires deciding on the energy vector from the design phase.
In practice, this means that a gas-heated home aiming for a subsidized overall renovation must plan for the replacement of the boiler within the project scope. Forgetting this point in the initial estimate blocks the Anah file.
Site scheduling: costly technical errors
An interior-insulated wall before the roof is redone risks water infiltration at the top of the wall. A facade coating applied before replacing the windows requires redoing the frames. These sequencing errors are common on projects managed without oversight.
The logical order remains stable:
- Roofing and framing first, to make the building waterproof and address dew points at the upper part.
- Exterior joinery next, to ensure airtightness before installing interior insulation or cladding.
- Insulation of opaque walls (walls, floors), then heating and ventilation networks, which depend on the volumes and flows calculated on the final envelope.
- Finishing work and details last, once the networks are pressure tested and the VMC balanced.
An intermediate air tightness test before finishing allows for detecting leaks at the level of electrical ducts and floor crossings. Correcting these defects after drywall installation costs much more than addressing them when exposed.
Materials and implementation: balancing quality and budget on a home project
The materials item represents a variable share of the budget depending on the level of service aimed for. We observe that the price gaps between bio-sourced insulation (wood fiber, cellulose wadding) and mineral insulation (glass wool, rock wool) have narrowed in recent years, making the choice more technical than economic.
The target thermal resistance, not the thickness, should guide the choice of insulation. A thicker wood fiber panel than glass wool can provide better thermal lag in summer, which is as important as winter performance in regions subject to repeated heatwaves.
On old stone or rammed earth walls, the permeability to water vapor of the insulation conditions the durability of the structure. Installing an inappropriate vapor barrier on a breathing wall causes internal condensation that degrades the structure within a few years. A moisture diagnosis before work avoids this trap.
Tools and safety on a self-renovation site
Work at height remains the leading cause of serious domestic accidents on private sites. For any elevation work, prefer a rolling scaffold over a simple ladder.
- Personal protective equipment: anti-splash goggles, FFP2 mask for cutting fibrous insulation, cut-resistant gloves for handling metal or glass.
- Collective protections: marking of openings, temporary guardrails on floors being removed, cutting off the electrical panel before any work on the network.
- Waste management: sorting on site (plaster, wood, metals, inert debris) conditions access to professional waste disposal sites and the cost of removal by truck.
A well-prepared site in advance costs less than a site salvaged mid-course. The study phase, often perceived as an unnecessary expense, rarely absorbs more than a modest fraction of the overall budget, but prevents rework whose cost can represent several times that amount.
