What Is Clay Tile Roofing?

What clay tile roofing is

Clay tile is one of the oldest roof coverings in the world. The National Park Service explains that clay tiles were first shaped by hand and later pushed through machines, then textured or glazed with color and fired in hot kilns ³. The heat turns soft clay into a hard, stone-like piece.

The classic color is the reddish brown known as terracotta. But clay tile also comes in buff, brown, black, green, blue and many glazed colors ³. Shapes vary too. Rounded barrel tiles, S-shaped tiles, and flat tiles that look like shingles are all common.

Concrete tile came along later as a stand-in for clay. The NPS describes it as a dense mix of portland cement, sand and pigment, pressed out by high-pressure machines ³. It copies the general look of clay.

The code handles both in section R905.3 and calls them clay and concrete tile ¹. So when this page says tile, it means both unless it says otherwise.

How a tile roof keeps water out

Tiles overlap, and many have curved shapes or locking edges. Rain runs over the tops and down into the channels between them. But tiles are not sealed to each other. Wind-driven rain can get between them, and some water does reach the layer below.

That layer is the underlayment, a waterproof sheet over the deck. The NPS notes that tile roofs have always needed some form of sub-roof or waterproof layer under the tiles ³.

This is why roofers often say the underlayment is the real roof on a tile job. If it fails, the house can leak even when every tile looks fine.

The code sets the underlayment by slope. Tile may go on roofs from 2½:12 up, but from 2½:12 to 4:12 the code asks for two layers of underlayment, since water moves more slowly there ¹. Learn more on our underlayment guide.

Tiles are held with corrosion-resistant nails, battens (wood strips the tiles hook onto), clips or approved adhesives.

The code asks for nails of at least 11 gauge with a 5/16 inch head, set at least 3/4 inch into the deck or through it ¹.

The number of fasteners per tile depends on slope and deck type, under Table R905.3.7 ¹.

Common tile shapes

Tile comes in many profiles. The names below are common trade names, not code terms.

Special pieces finish the roof: ridge and hip tiles, eave closures, and clay plugs called birdstops that keep rain, snow and birds out of the gaps under the first row ³.

Sources: [3]

Clay vs concrete tile

Clay and concrete tile look alike from the street, but they are made differently and age differently.

Weight differs by product and profile. Ask for the maker's weight per square for the exact tile on your quote, and have the frame checked against it.

Worked example: what does the code ask for on three roofs?

Take three illustrative homes and match them to the 2021 IRC tile rules ¹. A patio roof at 2:12 cannot take tile at all, because it is below the 2½:12 minimum; it needs a low-slope covering instead.

A ranch home at 3:12 can take tile, but it falls in the 2½:12 to 4:12 band, so the code calls for two layers of underlayment. A Mediterranean-style home at 5:12 can take tile with a single underlayment layer under R905.1.1.

On all three, the valleys need metal flashing of at least 26-gauge galvanized or an equal, reaching at least 11 inches each way from the valley center ¹. Check your own slope with the roof pitch calculator, then compare it with the tile maker's minimum, which can be higher than the code's.

Where tile roofing is used

Tile is common across the Sunbelt: Florida, the Southwest and California, on Spanish, Mission and Mediterranean homes. It is also found on older homes far from there. The NPS notes that tile was made in the New York and New Jersey area around the time of the American Revolution ³.

Tile suits hot, sunny places and areas with wildfire risk, because clay and concrete tile on a noncombustible deck are Class A ². It can also work in cold places, but only with the right tile.

The NPS warns that tile made for hot, dry climates may not stand up to wet weather or freeze-thaw cycles ³. In cold climates, ask for Grade 1 tile, which the TRI Alliance says is made for severe frost ⁵.

Benefits of tile roofing

• Long life. The NPS says clay tile has one of the longest life spans of historic roofing materials, generally about 100 years ³. The TRI Alliance says most makers offer warranties of 50 years or more ⁴.
• Fire resistance. Clay and concrete tile on a noncombustible deck are Class A, the highest class ².
• Low water uptake. The TRI Alliance gives an average moisture absorption under 1% ⁵.
• Hail. The TRI Alliance says many tiles resist up to 2-inch hail in the FM 4473 test ⁵.
• Wind. The TRI Alliance says tile systems can be designed for winds up to 200 mph ⁵. That depends on how the tiles are fastened.
• Low upkeep. The TRI Alliance calls glazed or matte clay essentially maintenance-free ⁴.

Limitations of tile roofing

• Weight. Tile is heavy. The TRI Alliance says many homes need little or no added reinforcement ⁴, but that is for an engineer to confirm, not assume.
• Breakage. The NPS says roofers walking carelessly, falling limbs and heavy hail can break clay tile, and high-profile tiles are very fragile ³.
• Underlayment life. The tiles can outlast the underlayment under them, so a tile roof may need its tiles lifted and relaid on new underlayment.
• Slope floor. Not allowed below 2½:12, and extra underlayment is needed up to 4:12 ¹.
• Matching. The NPS notes that old colors and glazes can be hard to match on repairs ³.
• Concrete color. Concrete tile tends to fade over time, per the NPS ³.

What drives the cost of a tile roof

We do not quote prices here. These are the things that move a tile quote up or down. Get a starting range for your home with the cost calculator.

• Clay or concrete. The NPS notes concrete tile reproduces the look of clay at a somewhat lower cost ³.
• Profile. Barrel and S tiles need more pieces and trim than flat tile.
• Glaze and color. Custom glazes and color matches cost more.
• Underlayment. Two layers on slopes from 2½:12 to 4:12 ¹, and upgraded underlayments add cost.
• Fastening. High-wind areas need more fasteners, clips or adhesive.
• Frame work. Any reinforcement an engineer calls for.
• Roof shape. Valleys, hips and chimneys need cut tiles and flashing.
• Reuse. Lifting and relaying sound tiles on new underlayment can cost less than all-new tile.

How a tile roof is installed

This is what you should see happen. It is not a do-it-yourself guide. Roof work is a fall risk, and a licensed roofer who installs tile should do it.

1. An engineer or the roofer confirms the frame can carry the tile chosen.
2. The crew checks the slope is at least 2½:12 and plans for double underlayment up to 4:12 ¹.
3. The deck is made solid, unless the job falls under the code's spaced-lumber exception in Seismic Design Categories A, B or C ¹.
4. Underlayment goes down, plus an ice barrier where the local code requires one.
5. Valley and wall flashings go in. See our valley flashing page for how valleys are built.
6. Battens are set if the system uses them, then tiles go on with the fasteners Table R905.3.7 calls for ¹.
7. Eave closures or birdstops, ridge and hip tiles finish the roof ³.

Caring for a tile roof

• Have a tile roofer check the roof after big storms and every few years.
• Ask them to look for cracked, slipped or missing tiles and for gaps at ridges and hips.
• Keep valleys and gutters clear, since debris dams water against the underlayment.
• Trim tree limbs; the NPS lists falling limbs among common causes of broken tile ³.
• Concrete tile can be gently washed by a pro at low pressure if wanted, per the TRI Alliance ⁴.
• Keep foot traffic off the roof; tell solar and dish installers to use a tile crew.

Warning signs and problems to watch

• Ceiling stains with no broken tile in sight, a sign the underlayment is wearing out
• Cracked tiles along paths where people have walked
• Slipped tiles, often from failed nails or battens
• Flaking or spalling faces on porous tiles after freeze-thaw cycles ³
• Missing birdstops at the eaves, which let birds nest under the tiles ³
• Rusted or open valley flashing

Each row is a likely cause to ask about, not a finding.

What the building code says about tile

These rules come from the 2021 International Residential Code, read as adopted in Maryland. Most states adopt the IRC, sometimes with changes, so your building department's edition is the one that applies.

Sources: [1] [2]

Tile vs other roof coverings

Slopes come from the same chapter of the 2021 IRC; fire classes from R902.1 ^{1 2}. See more side by side on the materials guide.

Common misconceptions

Myth If the tiles look fine, the roof is fine.

Reality Tiles shed most water, but the underlayment beneath them keeps the house dry, and it can wear out while the tiles still look new.

Myth Clay and concrete tile are the same.

Reality They are made differently, meet different standards (ASTM C1167 vs C1492), and the NPS notes concrete tends to fade ^{1 3}.

Myth Tile only works in hot places.

Reality Grade 1 tile is made for harsh winters and freeze-thaw, per the TRI Alliance ⁵. Tile made for dry heat may not last in the cold ³.

Myth White bloom on concrete tile is damage.

Reality That is often efflorescence, which the TRI Alliance calls temporary and harmless to the roof ⁴.

Myth Any house can take tile.

Reality Tile is heavy. Many homes need little added support, but an engineer should confirm it ⁴.

Local codes and climate

The rules on this page come from the 2021 International Residential Code. States, counties and cities adopt the code on their own schedule and often add their own tile rules, especially in high-wind and earthquake areas.

The spaced-lumber exception, for example, applies only in Seismic Design Categories A, B and C ¹. Your building department decides which edition applies and what wind and attachment rules govern your roof.

Climate is the other half. In freeze-thaw areas, ask for Grade 1 tile ⁵. In wildfire areas, tile on a noncombustible deck meets a Class A rating ².

In hurricane areas, the fastening method matters as much as the tile, so ask which tested attachment your roofer will use. In historic districts, a review board may require you to match the original tile.

Is tile roofing right for you?

• Tile is worth a look if your slope is at least 2½:12, your frame can carry it, and you want a long-life, fire-resistant roof.
• Pick clay for lasting color and a historic match; pick concrete for a similar look at a somewhat lower cost, knowing it can fade.
• In cold climates, ask for Grade 1 tile in writing.
• If your tile roof leaks but the tiles are sound, ask about lifting and relaying them on new underlayment.
• Weigh tile against lighter options with the material selector.

Keep going

• Roof replacementWhat a full reroof involves
• Roof repairFixing broken tiles and leaks
• Roof inspectionWhat a full roof check covers
• Choosing a rooferQuestions to ask before you hire

Related terms

Concrete Tile Roofing

Roof tiles cast from sand, cement and water, often colored to look like clay. They are heavy and need a frame rated for the load.

Slate Roofing

Slate roofing is a roof covering made of thin pieces of natural stone, split from quarried slate rock and nailed to a solid roof deck in overlapping rows.

Roof Underlayment

Roof underlayment is a sheet laid over the whole roof deck before the shingles or other roof covering go on.

Roof Pitch

Roof pitch is the steepness of a roof, written as the inches it rises for every 12 inches it runs horizontally, so a 6/12 roof climbs 6 inches per foot.

Valley Flashing

Valley flashing is the lining installed in a roof valley, the inside corner where two roof slopes meet, so the water both slopes send into that one line runs down to the eave instead of into the deck.

Roof Sheathing

Roof sheathing is the layer of plywood, OSB or wood boards nailed across the rafters or trusses.

Metal Roofing

Metal roofing is a roof covering made of metal sheets, panels or shingles, most often steel, aluminum, copper or zinc, fastened to the roof deck to shed water, snow and sun.

Asphalt Shingles

Asphalt shingles are roofing pieces made from a fiberglass mat coated with asphalt and topped with mineral granules, laid in overlapping rows so water runs off the roof.

Also referenced from: Slate Roofing, Wood Shakes