On a tile roof, the tile is not what keeps the rain out. The underlayment under the tile does that, and on a lot of Valley homes that are 20 years old or more, the tile still looks fine while the layer underneath is wearing out. If you are buying a home with a concrete or clay tile roof, the question to ask is not “how old is the roof?” It’s “how old is the underlayment, and what shape is it in?”
I’ve written before about how long a concrete tile roof really lasts in Arizona. Short version: the tiles usually outlive the paper under them. This post is about that paper, how I look for trouble with it, and what to do when the inspection points at it.
What the underlayment actually does
Tiles shed most of the water and take the sun. But tiles overlap, they crack, and wind-driven monsoon rain gets under them. The underlayment is the waterproofing barrier. Whatever gets past the tile runs down the underlayment, out to the edge of the roof, and off. If the underlayment is torn, brittle or missing, that water goes into the roof deck instead. Then it’s the same chain I talk about on almost every inspection: water gets in, wood rots, termites come.
On older Arizona roofs that underlayment is usually asphalt-saturated felt. Newer roofs often have a synthetic. For comparison, the University of Arizona’s own construction standards call for a minimum 30-lb asphalt-saturated felt or a synthetic underlayment under clay tile on campus buildings. Slope matters too. InterNACHI’s tile roof training notes that low-slope tile roofs, between 2:12 and 4:12, need a “double layer of underlayment beneath all of the tile”. Low-pitched patio covers and back roof sections are worth a closer look for that reason.
Why Arizona is hard on it
Heat and sun. That’s most of it. Felt is basically paper soaked in asphalt, and years of summer attic and roof-deck temperatures dry it out until it cracks when you bend it. Anywhere a tile has slipped or broken, the sun hits the underlayment directly and it goes even faster. Even the high-temp synthetics have limits. One manufacturer’s self-adhered tile underlayment, for example, is rated “UV resistant for up to 6 months of exposure”. It’s built to sit under tile, not to be the roof.
Then there’s debris. Bird droppings, leaves and dust pile up in valleys and behind flashing. If those channels aren’t wide open, water backs up, sits there wet, and finds its way past the tile. I had a leak at the front of my own house a few years ago from exactly this, so I pay attention to it.
What I look for from the roof and the attic
I can’t peel back the whole roof during a home inspection, and I’m not going to tell you the underlayment has a set number of years left. What I can do is look for the signs that point one way or the other. Here’s what goes in my notes:
- Exposed underlayment. Where a tile is broken or slipped, I look at what’s underneath. Brittle, cracked or torn felt tells me a lot about the rest of the roof.
- Cracks that matter versus cracks that don’t. Cracked tile corners are pretty typical out here. Not the end of the world, because the part protecting the roof is still covered. Once a crack runs up past the section where the tiles overlap, about 3 inches, that’s when I start worrying.
- Valleys and flashing. Packed with debris, covered over with roofing tar, or a cap sheet laid over the flashing so water can’t get down the channel. Water needs a clear path off the roof.
- Painted tiles and patchwork. Painted-over tiles and mismatched replacements usually mean somebody worked on the roof. I wrote up one of these in a roof repair second opinion where the tiles were painted. Painting tiles doesn’t do anything for the underlayment.
- Stains in the attic. Dark water stains on the roof sheathing or rafters, especially below valleys, around vent pipes and along the low edge of the roof. I check these with a moisture meter and a thermal camera when I can.
- Ceiling stains inside. A stain under a valley or a roof penetration is the house telling you where to look first.
One more thing. Not every tile roof should be walked. Old tile breaks underfoot, and every tile I break is a new hole for water. So some of my roof evaluation comes from the edges, from a ladder, from the attic, and from what’s going on inside the house.
What a lift and relay involves
When the underlayment is done, the usual fix on a sound tile roof is called a lift and relay, or an underlayment replacement. The roofer:
- Pulls the tiles and stacks them on the roof or the ground.
- Tears off the old underlayment down to the roof deck.
- Checks the sheathing and replaces any wood that’s rotted or soft.
- Installs new underlayment, plus new flashing at valleys, walls and vents where it’s needed.
- Puts the original tiles back and swaps out the broken ones.
It isn’t cheap, because it’s a lot of labor. But you’re keeping the tile, which is the part that lasts. The catch is matching. If enough tiles break and the profile or color isn’t made anymore, the replacements may not match. That ties into insurance, below.
Ask the roofer to put in writing what they’re replacing: underlayment type, flashing, how they’ll handle broken tile and wood repair. And check their license with the Arizona Registrar of Contractors before you sign anything.
Age and insurance questions to ask
Tile roofs get called “lifetime roofs” a lot. The tile might be. The underlayment isn’t. So during your inspection period, get answers to these:
- When was the underlayment last replaced? Not the tile repairs. The underlayment. If the answer is “never” on an older home, plan for it.
- Is there paperwork? Invoices, a permit, a written roof warranty, and the roofer’s name and license number.
- What did the seller disclose? Read what they wrote about leaks and roof repairs, and compare it to what the inspection found.
- What will your insurance do? Call your insurance agent before your inspection period ends, tell them the roof type and age, and ask how they handle it. Ask about matching too. ABC15 reported that in Arizona a standard policy “is only required to repair the damage, not to make it match”, and that normal wear and tear is on the homeowner. Worn-out underlayment is wear and tear.
What to do if the inspection flags it
Don’t panic, and don’t walk away over a few cracked corners. Do take it seriously when the signs point to the underlayment, because this is a water item. Here’s how I’d handle it:
- Get a licensed roofer out during your inspection period for an evaluation and an estimate. Ask them to lift a few tiles in the areas I flagged and photograph what’s under them.
- Get a real number. Not a guess and not “take a few thousand off.” An estimate in writing.
- Use it in your repair request. You can ask for the work or for a credit. If it were me, on a job this size I’d lean toward the credit so I can pick the roofer. Here’s how the BINSR works in Arizona.
- Keep the roof maintained after you move in. Clear valleys and flashing before monsoon season, replace broken tiles quickly, and keep people who don’t know tile off the roof.
At the end of the day it’s your call. I just want you to know what you’re buying so you can budget for it instead of finding out during the first big storm.
Tile roof inspections in Gilbert and across the Valley
The roof, the attic and the ceilings below are all part of every residential home inspection I do, whether the house is in Gilbert or out in Mesa and Chandler. Every home inspection includes a termite (WDO) inspection at no extra charge, plus a 1-year termite warranty through Firehouse Pest Control in Gilbert if no active termites are found.
Buying a home? Book your inspection online or call 623-399-0079.
Property Inspections Plus is a Gilbert, AZ home inspection company led by Certified Master Inspector Dan Pierce. We inspect homes across the East Valley, the Phoenix metro and the rest of Arizona. See all of our service areas.
