Time-to-build and the capital structure

•Calibrating time-to-build exogenous and endogenous growth models: the main issue.•Heterogeneous gestation lags in a model with N capital goods.•Long run dynamics: conditions under which a time-to-build model with one capital good and its counterpart with N capital goods are equivalent.•Illustrative numerical examples.

Calibrating the time-to-build parameter in one-sector models is non-trivial because capital includes plant, equipment, etc. having different gestation lags. This issue is clarified by explaining when the long-run dynamics of these models matches that of a more realistic multi-sector counterpart.