Map the changing geometry
Mark cones, rounded bays, curved eaves, dormers and changes in roof plane on the design drawings. For an existing roof, record the pattern on each form rather than assuming that every slope uses the same pieces. NPS notes that towers and turrets can use graduated sizes, while valleys, corners and other transitions may have purpose-made tiles.
Record rows as well as individual tiles
A representative loose tile may not describe a graduated roof. Measure and photograph the relationship between rows, including changes in tile width, length or visible exposure. NPS documents historic patterns that account for perspective as well as roof shape. Keep the row sequence intact in the survey so a replacement order does not erase an intentional progression.
Use a manufacturer’s geometry review
Ludowici describes field-measured graduated tiles that become smaller toward the top of a curved roof, and separate tower-tile options. These are product-specific approaches, not a universal solution for every curve. Provide measured geometry and ask which forms can be made for the chosen profile, then obtain confirmation of the proposed pattern before ordering standard pieces.
Resolve unusual pieces with the complete design
Custom profiles may help reproduce a shape unavailable in a standard family. Ludowici offers replication from samples and drawings. Connect custom pieces to the surrounding layout: identify their locations, their appearance from below and the evidence supporting their form on a historic building.
Review the transition at useful scale
Examine a physical sample arrangement or detailed drawing of the most visually demanding transition, such as a turret meeting a straight roof. Include the finishing piece at the top or edge. For historic work, GSA’s mockup approach helps establish a shared reference. Document the accepted arrangement so later substitutions are evaluated against the same visual and material intent.
Related questions
Further reading & technical sources
- National Park Service · Preservation Brief 30 ↗
- Ludowici · Graduated and tapered tile ↗
- Ludowici · Customization and historic matching ↗
- GSA · Clay roof tile repair and reattachment ↗
Consult the current product documentation and local requirements for your project. These introductions are not installation specifications.
Tile Roofing USA editorial guide · Published October 26, 2026.