A concrete or clay tile roof is two systems stacked together. The tile sheds most of the rain and blocks the sun. The underlayment beneath it is what keeps water that gets past the tile off the roof deck.
Why does the underlayment matter more than the tile?
The tile is rarely the weak point. The Tile Roofing Industry Alliance (TRIA) FAQ says tile roofs can last 50 to 100 years or more. The underlayment ages under the tile, where you cannot see it.
TRIA's technical brief on repairing storm-damaged tile says the underlayment acts as the secondary water barrier in most cases. It adds that underlayment not exposed to the weather will likely keep shedding water regardless of age. TRIA recommends a qualified contractor inspect the underlayment before any tile repair, and says new or harvested tiles should not go over compromised underlayment.
How do I know the underlayment is failing?
You usually find out from the inside first.
| Sign | What it can mean |
|---|---|
| Ceiling stains with no broken tiles visible | Water is getting past the tile and through the underlayment |
| Leaks at valleys, walls or skylights | Flashing or underlayment has failed at a transition |
| Brittle, cracked or torn underlayment where a tile is lifted | The layer has aged out in that area |
| Rotten or soft decking seen from the attic | Water has been reaching the deck for a while |
| Broken or slipped tiles after a storm | Underlayment below is now exposed to sun and rain |
A roofer can lift a few tiles in different areas to check. One bad spot may be a local repair. Brittle underlayment across several slopes points to full replacement.
What does the code require under the tile?
Section R905.3.3 of the Florida Building Code, Residential requires tile underlayment to follow the underlayment manufacturer's instructions in accordance with the FRSA/TRI Florida High Wind Concrete and Clay Roof Tile Installation Manual, Seventh Edition. Sections R905.3.6 and R905.3.7 point to the same manual for fasteners and tile application.
The Florida Building Commission describes the 7th Edition as a referenced standard in the Florida Building Code 8th Edition (2023). Its training on the manual covers underlayment, including self-adhered membranes.
Underlayment products carry Florida product approvals with their own installation limits. Ask your roofer which approved underlayment system they plan to use.
Does a tile reroof need a secondary water barrier and deck nailing?
Florida Statutes section 553.844 says a roof replacement must include secondary water barriers and strengthening or correcting roof deck attachment. The code's reroofing section, R908.7, carries that out for wood decks.
For tile, section R908.7.2 says clay and concrete tile roof systems installed as the Florida Building Code requires are deemed to comply with the secondary water barrier requirement. A correctly installed tile underlayment system is what satisfies it. Deck attachment still has to be checked and corrected where the tile and underlayment come off.
Can the old tiles go back on?
Often. Section R908.5 permits existing or salvaged slate, clay or concrete tile to be reinstalled. Salvaged tile must be of like kind in material and profile. Damaged, cracked or broken tile cannot be reinstalled, and rusted or deteriorated metal flashings, collars and edgings cannot go back either.
Reuse works best when:
- The tiles are sound and still made, or spares are on hand.
- There is space on the roof or ground to stack tile safely during the work.
- You accept that some tiles may break during removal and need matching replacements.
If your tile profile is discontinued, TRIA's brief describes a "harvest and repair" approach, taking tiles from less visible slopes to fix street-facing ones. New tile on those back slopes can look different up close. Discuss replacements before the job starts so there are no surprises.
Repair or full underlayment replacement?
| Situation | Usual approach |
|---|---|
| One leak at a valley, wall or penetration, underlayment elsewhere sound | Local repair, lift tile, replace underlayment and flashing, relay tile |
| Several slopes with brittle or torn underlayment | Full underlayment replacement with tile reinstalled |
| Many broken tiles or a discontinued profile | Full replacement with new tile |
| Planned work over 25 percent of a roof laid before the 2007 code took effect, in 12 months | Check the 25 percent rule before splitting the job |
Patching underlayment at a valley or one slope sits in our major repair range of $1,500 to $5,000. Doing the whole roof with new concrete tile is $28,000 to $50,000; the roof replacement cost page lists the house size and scope behind that figure.
Will a new underlayment affect insurance?
It can. A reroof permit, a sealed deck and documented deck nailing are items insurers and wind mitigation inspectors look for. See our wind mitigation inspection guide, the Florida 25 percent roof rule, and how long a roof lasts in Florida. Skylights on a tile roof are a common leak point, covered in our skylight leak guide.
Not sure what is under your tile? During a free roof inspection we lift a few tiles on different slopes and show you photos of the layer beneath. Our tile roofing service page covers the full job.
Sources
- 2023 Florida Building Code, Residential, 8th Edition, Chapter 9, Sections R905.3 tile and R908 reroofing
- Florida Building Commission, advanced course on FBC 8th Edition (2023) and the FRSA-TRI 7th Edition tile manual
- Florida Statutes s. 553.844, roof replacement requirements
- Tile Roofing Industry Alliance, frequently asked questions
- Tile Roofing Industry Alliance Technical Brief 2022-001, post-storm tile repair considerations
