Tile Roof Underlayment Replacement (Re-Felt) Explained

Many Arizona homeowners are surprised to learn that their tile is not what keeps the rain out. Concrete and clay tiles shed most water and shield what is underneath from sun, but some water always gets beneath them during heavy storms. The underlayment, a waterproof layer installed over the roof deck, is what stops that water from reaching your home.

Tile can last 50 years or more. Underlayment does not. Even though it is shaded, it is exposed to extreme attic and roof-surface heat year after year. Over time it dries out, becomes brittle, cracks and tears, especially around nails, valleys and edges. Once that happens, water that slips under the tile has a path into the deck and the house.

This is why a tile roof can look nearly perfect from the street and still leak. The failure is hidden. Often the first sign is a ceiling stain after a heavy monsoon storm, by which point water may have been reaching the deck for some time.

Not every aging tile roof needs the whole underlayment replaced at once. The right scope depends on what an inspection finds:

• Spot repair: one leak with a clear cause, such as a cracked tile or failed pipe flashing, on underlayment that is otherwise flexible and sound.
• Partial re-felt: one slope or section is worn, often the side that takes the most sun, while other areas still have useful life.
• Full re-felt: the underlayment is brittle or failing across the roof. At that point, doing everything at once avoids repeated tear-offs and gives you one consistent system.

An honest roofer will explain which category your roof falls into and why, ideally with photos of what is under the tile.

The term comes from the felt paper traditionally used as underlayment. Today, a re-felt may use felt or a modern synthetic or self-adhered underlayment depending on the roof and specifications. The idea is the same: renew the waterproofing layer, keep the good tile.

A re-felt is different from a tile repair. A repair might replace a few cracked tiles or patch a small area of underlayment. A re-felt replaces the underlayment across a section or the entire roof.

• The roof is around 20–30 years old or older and has never had its underlayment replaced.
• Leaks or ceiling stains appear after monsoon storms even though the tiles look fine from the ground.
• Repairs keep happening in different spots.
• A roofer lifting tiles finds underlayment that is brittle, cracked, torn or crumbling.
• Debris, dust or bird nesting material has built up under the tile, blocking water channels.
• Slipped or broken tiles have left underlayment exposed to direct sun.

Because you cannot see underlayment from the ground, a roof inspection is the way to know. An inspector can lift a few tiles in key areas to check its condition. Please do not try this yourself. Tile cracks easily under foot.

Every roof is different, but most re-felts follow a similar sequence:

1. Tile removal and staging. Tiles are carefully removed and stacked on the roof or ground. Ridge and hip tiles are removed too.
2. Old underlayment removal. The worn layer is stripped down to the deck.
3. Deck inspection. With the deck exposed, the crew checks for soft or damaged wood and replaces sections as needed.
4. New underlayment. Fresh underlayment is installed and lapped correctly so water flows down and out.
5. Flashings and battens. Valley metal, pipe flashings, wall flashings and battens are installed or replaced as needed. This is a good moment to address bird stops at the eaves.
6. Tile reinstallation. The original tiles go back on, and broken tiles are swapped with matching replacements where available.
7. Cleanup and final check. Debris and old fasteners are cleaned up and the roof is walked for a final inspection.

Some tiles will break

Older tile can be brittle, and a certain amount of breakage during removal is normal. Ask how replacement tiles will be matched. Some older profiles and colors are discontinued, so contractors may use salvaged tile or place newer tiles in less visible areas.

Check your HOA

If your tiles are going back on, the look of your home usually does not change, but some HOAs still want to be notified or approve roofing work. See our guide to HOA roofing rules.

Timing

Because the roof is opened up in sections, many homeowners prefer to schedule a re-felt outside of monsoon season. A good crew protects open areas whenever weather is a risk.

For many Arizona homes, yes. A re-felt keeps durable, attractive tile in place and renews the layer that actually fails. It also gives you a chance to fix decking, update flashings and deal with bird problems in one project.

Payne Roofing has worked on tile roofs across the Phoenix area and East Valley since 1984, and complete re-roofs include 10, 15 or 20-year warranty options. If your tile roof is getting older, an inspection is the best first step. You can also read more about the benefits of tile roofs.