The building (BT) indices are cost indices for different construction activity, apprehended from 6 positions in a cost accounting approach : "labour costs" once called "salaries and expenses", "materials" , "material", "energy", "transport", "miscellaneous expenses", similar to the productivity economists' approach called "KLEMS"(K = capital for "equipment", L = "Labour" ," E = "energy", M = "materials", S = "Services" for miscellaneous expenses) and which is added the position T (= transport) for "transport". Each position is it-self treated from elementary indices.

The structure and weights of the building (BT) indices have been reviewed on the occasion of the change in base and reference 2010.

Weights are constructed following, in particular, structural sources Insee and the work carried out with professional unions which rely on building site data returns.

BT indices are chained Laspeyres indices of elementary indices from public statistics, in particular the all employees-revised index of hourly labour cost (ICHTrev-TS) , the Industrial Producer and Import Price Indices (IPPI) and consumer price index (IPC).