Design guide · Guide 45 of 101

Diminishing-course slate roof design

Diminishing courses create perspective and refinement by using progressively smaller slate toward the ridge. The effect depends on exact mathematics and disciplined course control.

01

Design the sequence to fit the slope

The schedule assigns slate lengths and exposures to defined roof zones. Course totals must equal the available roof run while maintaining headlap at every change in size.

02

Coordinate width and thickness

Length is not the only variable. Widths and thickness can also transition to keep proportions convincing and courses stable. The material order should follow the approved schedule, not a general mixed-size allowance.

03

Resolve interruptions on paper

Dormers, valleys, hips and roof breaks interrupt the sequence. Draw course lines through these areas so corresponding elevations align and the diminution does not restart awkwardly.

Further technical reading

Recognized sources behind this guide

Slate Boss writing is original. These links provide additional standards, preservation guidance and industry reference material.

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