Laying Sand and Cement Screeds to Levels and/or Falls in the Workplace

"Laying (...) screeds to levels", в принципе, ясно. Но что такое "laying (...) screeds to falls"?

Вот весь контекст:
I) Screeding to Falls:
a) Minimum screed cover: Maintain at the lowest point.
b) Falls: Gradual and consistent.

Заранее благодарен за помощь!