A reserved hole can be left in the roof of the civil air defense basement for the production of materials.

A facility hole can be left at the top of the civil air defense basement to facilitate the transportation of basement materials; However, it is necessary to avoid the parts with large stress, and reserve water-stop steel plate or rubber water-stop tank to meet the waterproof requirements. If the opening size is large, hole reinforcement should be added as required.

Civil air defense basement: a kind of civil air defense works, including external walls, buffer walls, explosion doors, closed walls, protective partitions, etc. , mainly used for civil air defense temporary bunkers, wartime air defense command centers, communication centers, hidden places, etc. Some permanent fortifications also have the function of three defenses.

Function: to ensure the needs of civil air defense command, communication and shelter. There is a predetermined protective function in the basement, and it also has the function of storing food and fresh water in an emergency.