Sovereignty Module: Crown the Roof
Complete Clay Tile Roofing: From Clay to Weatherproof
Clay roof tiles have protected buildings for 5,000 years. This campaign covers tile making, kiln firing, roof structure, and installation.
Chapter 1: Tile Types
| Type | Shape | Overlap Method | Weight (per sq ft) | Difficulty |
|---|---|---|---|---|
| Flat tile (plain) | Flat rectangle with nibs | Double overlap | 8-12 lbs | Low |
| Pan and cover (mission) | Half-cylinder alternating | Concave/convex pairs | 10-15 lbs | Moderate |
| S-tile (Spanish) | S-curve profile | Interlocking S-curves | 8-12 lbs | Moderate |
| Roman tile (tegula and imbrex) | Flat pan + half-round cover | Cover caps pan joints | 12-16 lbs | Moderate |
| Interlocking tile | Complex profile with channels | Mechanical interlock | 8-12 lbs | High |
Chapter 2: Tile Making
Flat tile production: 1) Prepare clay body (same as brick clay: clay + sand, 70:30 ratio). 2) Wedge clay thoroughly (remove air bubbles). 3) Roll clay slab to uniform thickness (1/2-3/4 inch). 4) Cut to size using template (typically 6x10 inches or 8x12 inches). 5) Form hanging nibs: press small clay bumps on back near top edge. 6) Nibs hook over roof battens (hold tile in place). 7) Smooth surfaces with damp sponge. 8) Dry slowly on flat surface (1-2 weeks). 9) Fire in kiln to cone 06-1 (1800-2100°F). 10) Higher firing = more waterproof and durable.
Pan and cover (mission tile): 1) Prepare clay slab (1/2-3/4 inch thick). 2) Drape slab over half-round form (log or pipe, 4-6 inch diameter). 3) Trim edges to length (14-18 inches). 4) Remove from form when leather-hard. 5) Make equal numbers of concave (pan) and convex (cover) tiles. 6) Pan tiles lay concave-up (channels for water). 7) Cover tiles lay convex-down over pan joints. 8) Dry and fire same as flat tiles.
Chapter 3: Roof Structure for Tile
| Component | Material | Size | Spacing | Purpose |
|---|---|---|---|---|
| Rafters | Timber | 2x6 or 4x4 minimum | 16-24 inches | Primary roof structure |
| Purlins | Timber | 2x4 or 3x3 | 24-36 inches | Support battens |
| Battens (lath) | Wood strips | 1x2 inch | Tile gauge (exposure) | Tile hanging surface |
| Ridge beam | Timber | 2x6 or larger | One at peak | Top of roof |
| Underlayment (optional) | Bark, thatch, or felt | Continuous | Full coverage | Secondary waterproofing |
Roof pitch requirements: 1) Flat tiles: minimum 35-40 degree pitch (steep). 2) Pan and cover: minimum 25-30 degree pitch. 3) Interlocking tiles: minimum 20-25 degree pitch. 4) Steeper pitch = better water shedding = longer tile life. 5) Tile roofs are heavy (800-1,500 lbs per 100 square feet). 6) Roof structure must be sized for tile weight plus snow load.
Chapter 4: Installation
Flat tile installation: 1) Install battens horizontally across rafters. 2) Batten spacing = tile length minus overlap (typically 3-4 inch overlap). 3) Start at bottom edge of roof (eaves). 4) First course: hang tiles on batten with nibs. 5) Tiles overlap side-to-side by 1-1.5 inches. 6) Second course: offset tiles by half-width (stagger joints). 7) Each tile overlaps the one below by 3-4 inches. 8) Continue up roof, course by course. 9) Cut tiles to fit at edges (score and snap or use tile cutter). 10) Cap ridge with special ridge tiles (half-round, mortared in place).
Chapter 5: Durability and Maintenance
| Factor | Effect | Maintenance |
|---|---|---|
| Frost damage | Porous tiles absorb water, freeze, crack | Use well-fired tiles, replace cracked ones |
| Wind uplift | Tiles can be lifted by strong wind | Nail or wire every 3rd-4th tile, all edge tiles |
| Moss/lichen growth | Holds moisture, can lift tiles | Remove periodically, improve sun exposure |
| Broken tiles | Leak at break point | Replace individual tiles (advantage of tile roofing) |
| Ridge mortar | Cracks and falls out over time | Re-point every 10-20 years |
Reference Card
- Clay tiles last centuries (properly fired clay roof tiles have survived 500+ years on buildings in Europe and Asia; they are the most durable roofing material). 2. Tile roofs are heavy (plan the roof structure for 10-15 pounds per square foot of tile plus snow load; undersized rafters sag and fail). 3. Overlap prevents leaks (each tile overlaps the one below and the one beside it; water runs down the overlapping surfaces and never reaches the interior). 4. Stagger the joints (offsetting each course by half a tile width ensures that no vertical joint aligns with the one below; aligned joints create leak paths). 5. Start at the eaves (tile installation always begins at the bottom edge and works upward; each course covers the top of the course below). 6. Nibs hold the tile (small clay bumps on the back of each tile hook over the batten; gravity and friction do the rest). 7. Individual tiles are replaceable (unlike sheet roofing, a single broken tile can be removed and replaced without disturbing the rest of the roof). 8. Higher firing means longer life (tiles fired to higher temperatures are denser, less porous, and more resistant to frost damage; invest the extra fuel in proper firing).