Building overlays can be classified into wooden formwork, bamboo plywood and steel film board.

1. Wooden template: wooden mould used for concrete casting and forming, including poplar, pine, press wood and other kinds of wood.

2. Bamboo plywood: used as a bamboo mould for concrete pouring and forming. Nanzhu is commonly used as the main material in the market.

3. Steel template: this should be well understood, it is the traditional steel products made of abrasive tools.