The construction cost index (CCI) published by Insee stands at 2,084 points in the first quarter of 2026, down 2.89% year-on-year. This figure marks a clear turning point after several years of continuous increases. Understanding the mechanisms behind this decline requires distinguishing between the prices charged to project owners and the actual costs borne by construction companies.
Margin compression in construction: the hidden driver of price decline
Most analyses focus on material prices to explain the evolution of construction costs. The most revealing angle in 2026 lies elsewhere: in the growing gap between charged prices and production costs.
The CCI, which measures the prices actually charged for new residential buildings, is declining. At the same time, the construction production cost index (CPI-F) continues to rise slightly, with an increase of 1.4% over the quarter and 2.1% year-on-year in the first quarter of 2026. Energy, certain materials, and labor still push this index upward.
This discrepancy means that construction companies are absorbing part of the increase in their expenses by reducing their margins. Order books, considered to be more depleted than in the previous quarter according to economic surveys, create competitive pressure that drives quotes down. Major European construction firms report solid overall revenue results, but their margins on pure construction are eroding, as noted in several semi-annual reports published in mid-2026.
In practical terms, an individual starting a construction project in 2026 benefits from this increased competition among companies, even if material prices have not significantly decreased. To follow this dynamic, the forecasts from Projet Immobilier detail the scenarios of evolution item by item.
BT01 index and CCI: two indicators not to be confused when reading quotes
Talking about a decline in construction prices without specifying which indicator is being used amounts to comparing incompatible data. Two indices coexist and do not measure the same thing.
The CCI reflects the selling price of new buildings, as charged to the end customer. It incorporates margins, productivity, and market conditions. Its decline of 2.89% year-on-year reflects a market adjustment.
The national building index BT01 (all trades) measures the cost of production factors: materials, wages, overheads, energy. It remains moderately upward-oriented, confirming that the decline in the CCI does not stem from a drop in inputs.
- The CCI serves as a reference for the revision of commercial rents and certain promotion contracts. Its decline has a direct impact on rental charges and exit prices of new programs.
- The BT01 is used for price revision in work contracts. A stable or slightly rising BT01 means that quotes signed with a revision clause will not mechanically decrease.
- The CPI-F, less known, measures actual production costs. Its discrepancy with the CCI reveals the pressure on builders’ margins.
Before negotiating a quote, checking which index serves as the basis for the revision clause allows for anticipating adjustments during the project.
Energy and construction materials: a partial calm in 2026
The price of energy remains a major determinant for cement, glass, steel, and insulation materials, all of which are energy-intensive in thermal processes. In 2026, oil and gas prices are below their peaks from the 2022-2023 period, which slows the rise in production costs without causing a significant drop.
Construction steel stabilizes after the strong fluctuations of previous years. Wood has seen a relative calm since the shock of 2021, although demand related to bio-sourced construction maintains structural tension.
The weight of environmental regulation on costs
The RE2020, applicable to permits filed since 2022, imposes increasingly strict carbon thresholds. The adjustments planned for permits filed after July 2025 further strengthen these requirements. The use of low-carbon materials (wood, decarbonized concrete, bio-sourced insulation) increases costs in certain areas.
This regulatory pressure prevents a return to pre-crisis price levels. Prices are falling due to competition, not due to a decrease in inputs. The RE2020 acts as a structural floor on the production cost of new buildings.
Construction market situation in 2026: depleted order books and reduced activity
The first quarter of 2026 confirms a slowdown in activity in construction. Economic surveys report order books considered to be more depleted than in the previous quarter. The number of building permits issued remains below the volumes observed before 2022.
This context of underactivity produces a direct effect on prices. Companies, to maintain their workload, accept lower margin levels. Fewer projects mean more competition for each tender, which drives quotes down.
Large groups partially compensate through diversification (concessions, energy), but artisans and SMEs in construction feel this pressure more directly. For a project owner, the balance of power temporarily shifts: the negotiating capacity on a new construction or renovation quote is more favorable than it was in 2023 or 2024.
The question of how long this window will last remains open. A potential construction stimulus plan or a revival of mortgage credit could refill order books and reduce competitive pressure. The CCI for the second quarter of 2026, expected in the fall, will provide an indication of the persistence – or not – of this downward trend.