how to calculate tributary area: The area that it supports equals the tributary width times the unit length.

A parapet is a barrier that is an extension of the wall at the edge of a roof, terrace, balcony, walkway or other structure. 

A salt finish is a simple and inexpensive way to dress up what would otherwise be plain concrete flatwork.

what is a well point system: Wellpoint systems are used to lower groundwater levels to provide stable working conditions.