Tile Making

Part of Permanent Shelter

Clay tiles are the most durable roofing material you can produce without metal tools or industrial equipment. A properly fired tile roof lasts 50–100 years — some Roman tile roofs survived for over a millennium. Tiles are fireproof (unlike thatch), resist rot and insects, and improve with age as they harden further. The trade-off is effort: tile production requires finding suitable clay, forming hundreds of individual tiles, drying them carefully, and firing them in a kiln. But once installed, tiles outlast every other primitive roofing option by decades.

Clay Selection and Preparation

Not all clay makes good tiles. The wrong clay produces tiles that crack during drying, shatter during firing, or crumble on the roof.

Finding Good Tile Clay

Look for clay deposits along riverbanks, road cuts, hillside exposures, or anywhere erosion reveals subsoil. Good tile clay has these properties:

Property	Test	Pass Criteria
Plasticity	Roll a pencil-thick coil and bend it into a ring	Should bend without cracking or breaking
Grit content	Rub between fingers	Should feel smooth with fine grit, not chunky or sandy
Color	Visual	Red, brown, grey, or buff — pure white kaolin is too refractory for primitive kilns
Shrinkage	Dry a small flat piece and measure	Should shrink 5–8%. Over 10% means too much clay (add sand). Under 3% means too sandy.

Preparing the Clay

Raw clay from the ground contains stones, roots, organic matter, and inconsistent moisture. It must be processed before forming tiles.

1. Dig and stockpile: Excavate clay and pile it in the open. Exposure to rain, sun, and frost over 2–4 weeks (called “weathering”) breaks down lumps and improves workability.

2. Remove debris: Pick out stones, roots, and organic material by hand. For finer results, slake the clay: soak it in water until it dissolves into a thick slurry, strain through a coarse mesh (woven basket), and let the strained slurry settle. Pour off excess water once the clay settles to a workable consistency.

3. Add temper: Mix in fine sand (10–20% by volume) if the clay is very plastic (high shrinkage). Sand reduces cracking during drying and firing. The target is a clay body that shrinks 5–8% when dried and does not crack.

4. Wedge (knead): Work the clay by hand — fold, press, turn, repeat — for 5–10 minutes per batch. This aligns the clay particles, removes air bubbles, and creates a uniform consistency. Air bubbles trapped inside tiles explode during firing.

Air Bubbles Kill Tiles

A single trapped air pocket in a tile will expand violently during firing, shattering the tile and potentially damaging adjacent tiles in the kiln. Wedge the clay thoroughly. Slam each lump against a hard surface several times before forming. If you hear a pop when you cut a clay lump in half with a wire or string, air bubbles are still present — continue wedging.

Tile Shapes

Three basic tile shapes cover all roofing needs. Start with flat tiles — they are the easiest to make.

Flat Tile

A rectangular slab, typically 25–30 cm long, 15–20 cm wide, and 1–1.5 cm thick. The simplest to produce.

• Pros: Easy to mold, stack for transport, and replace individually
• Cons: Requires good overlap and precise pitch to prevent leaks at the flat joints

Curved Tile (Pan Tile / Imbrex)

A half-cylinder shape formed over a curved mold (a log section or split bamboo). Used in pairs: one concave (channel) and one convex (cover), alternating across the roof.

• Pros: Excellent water channeling, very leak-resistant
• Cons: Heavier, requires more tiles per area, harder to form consistently

Interlocking Tile

A flat tile with a raised lip on one edge and a matching groove on the opposite edge. When laid, each tile locks into its neighbor.

• Pros: Most wind-resistant, minimal overlap needed
• Cons: Complex mold, must be very consistent in size — variations prevent interlocking

Start with Flat Tiles

For your first tile roof, make flat tiles. They forgive inconsistency in size and shape, and a slightly irregular flat tile still works. Curved and interlocking tiles require precision that comes with practice — graduate to them after your first batch of 50–100 flat tiles.

Making Tile Molds

A mold ensures consistent dimensions and speeds production dramatically.

Flat Tile Mold

1. Build a rectangular frame: Four pieces of straight-grained wood (2 cm thick), assembled into a bottomless rectangle matching your tile dimensions (e.g., 28 x 18 cm internal dimensions — slightly oversized to account for 5–8% shrinkage).
2. Base board: Cut a flat board slightly larger than the frame. This is your forming surface.
3. Release agent: Dust the base board and inside of the frame with fine sand or dry ash before each use to prevent sticking.

Curved Tile Mold

1. Find a curved form: A log section 15–20 cm in diameter works. Split it in half — one flat side down, curved side up.
2. Cover with fabric: Wrap the curved surface with a piece of cloth or animal skin. This prevents the clay from sticking and makes release easy.
3. Form over the curve: Drape a flat slab of clay over the covered form, trim to size, and let it stiffen before removing.

Production Rate

Method	Tiles per Person per Day	Tiles Needed (3 x 4 m roof)
Flat tile with mold	40–60	250–350
Curved tile (pan + cover)	20–30 pairs	200–250 pairs
Interlocking tile	25–40	200–300

Plan for 10–15% breakage during drying and firing. Make extras.

Forming Tiles

Flat Tile Step-by-Step

1. Prepare a clay slab: Cut a lump of wedged clay and flatten it with your palms or a flat stick to approximately 1.5 cm thick. Use two guide sticks (1.5 cm thick) on either side and roll a straight stick across them to achieve uniform thickness.

2. Fill the mold: Place the frame on the sanded base board. Lay the clay slab into the frame, pressing it firmly into all corners.

3. Strike off: Run a straight edge (stick or board) across the top of the frame to remove excess clay and create a flat, even surface.

4. Add hanging nibs: On the underside of one short edge, press two small clay knobs (1.5 cm wide, 1 cm tall) about 5 cm from each corner. These nibs will hook over the roof battens to hold the tile in place. Alternatively, press a pointed stick through the tile near the top edge to create a peg hole for fastening.

5. Release: Carefully lift the frame straight up. The tile should remain on the base board.

6. Transfer to drying area: Slide the tile (on its base board or on a sand-dusted surface) to the drying area. Do not pick up wet tiles — they deform under their own weight.

Curved Tile Step-by-Step

1. Roll a flat slab: 1–1.5 cm thick, slightly larger than needed.
2. Drape over the mold: Lay the slab over the fabric-covered log section. Press gently to conform to the curve. Trim excess with a sharp edge.
3. Let stiffen: Leave on the mold for 30–60 minutes until the clay firms enough to hold its shape.
4. Remove: Lift carefully using the fabric as a sling. Set the tile curved-side-up on a flat, sanded drying surface.

Drying Process

Drying is the stage where most tiles are lost to cracking. The key is even, slow drying.

Stage	Duration	Action
Initial set	12–24 hours	Leave flat on drying surface. Do not move or touch.
Slow dry	3–5 days	Move tiles to a shaded, ventilated area. Direct sun causes uneven drying and cracking. Turn tiles once daily for even air exposure.
Final dry	5–10 days	Tiles can tolerate direct sun once the surface is no longer cool to the touch. Fully dry tiles are lighter in color and feel warm, not cool, when held against your cheek.
Ready test	—	Break a test tile in half. The interior should be the same color as the surface — no dark, damp core.

Never Fire Damp Tiles

Steam from residual moisture expands explosively in a hot kiln. Every tile must be bone-dry before firing. If you can feel any coolness at the center (moisture evaporating), dry longer. Firing damp tiles wastes fuel, shatters tiles, and can damage the kiln.

Firing Temperatures

Firing transforms fragile dried clay into hard, weather-resistant ceramic. The higher the temperature, the harder and more waterproof the tile.

Temperature	Result	Method to Achieve
600–700°C	”Biscuit” fired — hard but porous, absorbs some water	Open bonfire or simple pit kiln
800–900°C	Standard fired — hard, low porosity, adequate for roofing	Basic updraft kiln (clay or stone chamber)
1000–1100°C	High-fired — very hard, nearly waterproof, rings when tapped	Well-built kiln with forced draft or bellows

Building a Simple Updraft Kiln

1. Dig a pit 1 m wide, 1.5 m long, 60 cm deep with a trench (fire channel) leading to one end.
2. Build walls from adobe or stacked stone around the pit edges, rising 60–80 cm above ground.
3. Create a grate: Lay a grid of greenwood poles or flat stones across the pit, 30 cm above the fire channel. This separates tiles from the fuel and allows heat to rise through.
4. Stack tiles: Place tiles on the grate, standing on edge with 2–3 cm gaps between each tile for heat circulation. Do not stack flat — airflow is critical.
5. Cover: Place broken tiles or flat stones over the top, leaving gaps for exhaust.
6. Fire: Start with a small fire in the channel, building slowly over 4–6 hours. Rushing the temperature cracks tiles. Maintain peak temperature for 2–4 hours. Let the kiln cool completely (12–24 hours) before opening.

Test Fire First

Fire 10–15 test tiles before committing to a full batch of 200+. Check the results: do they ring when tapped? Can you scratch them with a fingernail (if yes, underfired)? Do they absorb water when soaked for an hour (weigh before and after — more than 10% weight gain means underfired)? Adjust kiln design, fuel, and firing time based on results.

Laying Tiles on Roof Battens

Once fired, tiles are installed on the roof frame.

Prepare the Roof

1. Install battens: Nail or peg horizontal battens (5–8 cm diameter poles) across the rafters. Spacing equals the tile exposure — typically the tile length minus the overlap. For a 28 cm tile with 8 cm overlap, batten spacing is 20 cm.

2. Start at the eaves: The first row of tiles sits at the bottom edge of the roof. Overhang the eaves by 5–8 cm so water drips clear of the wall.

Laying Pattern

1. Hook or peg each tile: Hang tiles from the batten using the nibs on the underside, or thread a wooden peg through the hole and hook it over the batten.

2. Overlap side-to-side: Each tile overlaps its neighbor by 3–5 cm. This prevents wind-driven rain from entering lateral joints.

3. Overlap top-to-bottom: Each course overlaps the course below by one-third to one-half the tile length. Water running down a tile drops onto the course below, not into the joint.

4. Stagger joints: Offset each course by half a tile width so vertical joints never align between courses. This is the same principle as bricklaying — aligned joints create a direct leak path.

5. Work from eaves to ridge: After the bottom course, add courses moving upward. At the ridge, cap with purpose-made ridge tiles (see Ridge Capping).

Fastening Methods

Method	Materials	Wind Resistance	Notes
Hanging nibs	Clay (built into tile)	Moderate	Tiles hook over battens by gravity — adequate in sheltered locations
Peg-and-hole	Wooden pegs	Good	Peg through tile hole, hooked over batten — positive fastening
Mortar bedding	Clay or lime mortar	Excellent	Tiles set in mortar at eaves, ridge, and edges — most wind-resistant
Wire tie	Twisted wire (if available)	Excellent	Wire through hole, twisted around batten — modern method

Secure the Vulnerable Zones

Even if most tiles rely on gravity (hanging nibs), always positively fasten tiles at the eaves (bottom edge), verges (side edges), and ridge. These are where wind uplift is strongest. A few pegs or mortar dabs at these critical points prevent the most common tile failure — edge tiles lifting in wind and cascading down the roof.

Advantages Over Thatch

Factor	Clay Tiles	Thatch
Lifespan	50–100+ years	15–30 years
Fire resistance	Fireproof	Highly flammable
Pest resistance	Immune	Attracts rodents and insects
Maintenance	Minimal	Annual inspection and patching
Minimum pitch	30°	45°
Weight	Heavy (40–60 kg/m2)	Light (15–25 kg/m2)
Insulation	Poor — requires underlay	Excellent
Production effort	High (forming + firing)	Low (harvesting + bundling)

Tiles win on durability and safety. Thatch wins on speed, insulation, and simplicity. In practice, many historical buildings used thatch initially and upgraded to tiles once the settlement had the labor and kiln capacity to produce them.

Key Takeaways

• Good tile clay is plastic, smooth, and shrinks 5–8% when dried. Add 10–20% sand to high-shrinkage clay. Wedge thoroughly to remove air bubbles.
• Start with flat tiles (easiest): 25–30 cm long, 15–20 cm wide, 1–1.5 cm thick. One person can produce 40–60 per day with a mold.
• Dry slowly in shade for 3–5 days before moving to sun. Tiles must be bone-dry before firing — cool center means moisture remains.
• Fire in an updraft kiln to 800–900°C for standard tiles. Test-fire a small batch first; check hardness, ring, and water absorption.
• Lay on battens from eaves to ridge. Overlap one-third vertically, 3–5 cm laterally, stagger joints. Fasten edges, eaves, and ridge positively.
• Tiles outlast thatch by decades and are fireproof, but require more production effort and a stronger roof frame to support their weight.
• Plan for 250–350 flat tiles for a small building (3 x 4 m), plus 10–15% extra for breakage.