BT01 Index - National Building Index (all trades)

BT01 Index – National Building Index (all trades)

Published on 9 November 2019 at 16:26

Updated on 7 February 2026 at 12:07

By: Pascal FROMAGER

2026 salaries and collective agreements: making the law accessible to everyone

The BT01 Index is France’s national construction index (all trades).

It measures changes in the cost of factors of production in the building industry and is the official reference for updating and revising construction contract prices.

The Index was created by a decree published in the Official Journal on December 20, 2014 (base 100 = 2010 average) and is published monthly by INSEE. It thus succeeds the Index of Building and Public Works (bases 1974 and 1975), which has been discontinued.

BT01: latest index years values — Download the latest official values of the BT01 Index

BT01 Index History

Below are the values of the Index by year with the changes compared to the previous month, the beginning of the year, over 12 months, and over 24 months:

BT01 2024 – National Building Index (all trades)

BT01 2023 – National Building Index (all trades)

BT01 2022 – National Building Index (all trades)

BT01 2021 – National Building Index (all trades)

Use of the BT01 Index:

Rule:

The price of the contract of services will be revised at each expiry of the agreement according to a formula that integrates the evolution of the BT01 Index.

Formula:

[New price] = [old price] X [Known reference index BT01] / [Reference index BT01]

Attention, do not confuse the BT01 Index with the “Construction Index” or the “Rent Reference Index” used to revise rents for private individuals and leases for professionals.

Latest BT01 Index Updates:

Latest values of the building index BT01 – All trades – Base 2010:

BT01 2024 – National Building Index (all trades)

Frequently Asked Questions about the BT01 Index

What is the BT01 index?

The BT01 index, a crucial benchmark in France’s construction and public works (BTP) sector, plays a significant role in reflecting the evolution of construction costs, particularly for single-family homes. This index is instrumental in adjusting specific construction contracts in response to fluctuations in the prices of materials and labor. Published monthly by INSEE, with a typical lag of about two months, it’s a key tool for contract management. For instance, the index for January will be published in March.

How is the BT01 index calculated?

The BT01 index is meticulously calculated, considering several factors, including the construction sector’s cost of materials (such as concrete, wood, and steel) and labor. This precision ensures it is a reliable representative of price variations across the entire building and public works sector.

How do you use the BT01 index to revise a contract?

A revision clause must be included in revising a contract with the BT01 index. This clause specifies that the contract amount may be revised based on changes in the index between the date of signature and a later date (often the end of the project). The price revision uses a formula that considers the index’s evolution between two dates, typically the percentage change in the index multiplied by the original contract amount.

We’re interested in your opinion on BT01 index evolution:

Tell us in the comments. THANKS.