What is Wythe?

Definition of Wythe in Construction

A single course of masonry. In years gone by , the installation of several wythes of brick or block made up the exterior facades of structures. When the only method available to construct a building of several stories, besides wood, was masonry construction, the number of masonry wythes was maximized at the bottom elevations and decreased as the structure rose. This construction was based on the structural concept ,that the most strength was required at the base of the structure where the loading was the highest, and as the building rose in height, the actual forces on the exterior walls were reduced, therefore the number of wythes of masonry could be reduced. This method of construction is why many of the brownstones of NYC or Boston have a lower structure that may entail a width of several feet, where the masonry wythes are numerous, tapering away as the building rises in height. With the development of the cast iron structures and then the steel structures, the need for thick masonry walls was eliminated. There are very few construction details that are commonly used that require numerous courses of masonry. The only reason for multiple whythes of masonry, would be to obtain a fire rating of several hours. The majority of construction is one wythe of block as a backup block system for one wythe of brick veneer.