When should you replace roof tiles, and how is it done?

Tile roofs are two roofs in one

The tiles shed most of the water and protect against sun, but the underlayment below is what keeps the house dry when wind-driven rain gets past them. Tiles can last 50 years or more. The underlayment, battens and flashing usually give out first, which is why a tile roof can leak with every tile intact.

When to replace individual tiles

• Cracked or broken tiles, often from foot traffic or falling limbs.
• Slipped tiles whose fasteners or clips have failed.
• Pieces chipped by hail. Concrete and clay tiles can crack in a hailstorm, and damaged tiles let water reach the underlayment.

How a broken tile is replaced

1. Lift or slide the overlapping tiles above the broken one, supporting them so they do not crack.
2. Break out the damaged tile carefully and cut or remove its fastener.
3. Set the new tile, matching profile and color, and secure it with a clip, hook or approved adhesive as the tile maker specifies.
4. Lower the surrounding tiles back into place.

Matching can be hard on older roofs because tile profiles get discontinued and colors weather. Salvaged tiles from a hidden area are sometimes used.

When to lift and relay

If leaks keep appearing with no broken tiles, or the roof is past 20 to 30 years, the fix is often to remove the tiles, replace underlayment and flashing, and reinstall the good tiles. Leak sources are covered in common causes of roof leaks, and underlayment options in synthetic underlayment vs felt.