This structure was designed to be more solid when used on longer spans and with heavier loads.[3] This type of structure, because of its rigidity, is recommended for buildings that require minimal vibration, like laboratories and manufacturing facilities.[3] It is also used in buildings that require big open spaces, like theatres or train stations.[2] Waffle slabs are composed by intricate formwork, and may be more expensive than other types of slabs, but depending on the project and the quantity of concrete needed it may be cheaper to build.