How much does it cost to replace underlayment on a tile roof?
Short answer. Replacing underlayment on a tile roof is a labor-heavy job: every tile is lifted and stacked, the old underlayment and often the battens are removed, new underlayment and flashing go down, and the tiles are relaid, with broken ones replaced. It often costs as much as or more than a full shingle replacement on the same area, and the price depends mainly on roof size, tile type, breakage and how hard matching replacement tiles are to find.
Why the underlayment fails first
Clay and concrete tiles can last for many decades, but the underlayment beneath them is the real waterproofing layer, and it ages much faster. Heat under tiles, especially in Georgia summers, dries out felt underlayment until it cracks. Leaks then show up at valleys, around penetrations and at the eaves while the tiles still look fine.
How the job is done
- Tiles are removed carefully and stacked on the roof or ground, sorted by type.
- Old underlayment, battens and failed flashing are torn off.
- Decking is inspected and repaired.
- New underlayment goes down, often a high-temperature synthetic or self-adhered membrane rated for tile.
- New battens and flashing are installed at valleys, walls, chimneys and penetrations.
- Tiles are relaid and fastened to current requirements, with broken tiles replaced.
What drives the cost
- Roof area and complexity. Hips, valleys and penetrations slow the work.
- Tile type. Clay is more brittle than concrete; more breakage means more replacements.
- Matching tiles. Discontinued profiles or colors can be hard to find and may require salvaged tiles.
- Weight and access. Heavy tiles take time to move safely.
- Decking repairs found once the roof is open.
Choosing a contractor
Tile requires specific experience, and walking on tile wrong breaks it. Ask how many tile relays a contractor has done and how they handle breakage. Get two opinions on whether a targeted repair at valleys and penetrations could buy time. See synthetic underlayment vs felt and common causes of roof leaks.