Roofing
What does replacing roof underlayment cost in Phoenix?
On a tile roof — which is most Valley roofs — published Phoenix figures for lifting the tile, replacing the underlayment and relaying run roughly $3 to $12 per square foot, or about $11,550 to $28,900 on a typical house. The page that ranks for this search quotes $2 per square foot, because it is quietly pricing shingle underlayment and never says so.
What moves yours is tile versus shingle, the square footage, how much decking turns out to be bad once the tile is off, and how much tile breaks on the way down.
Vincenzo DiGennaro · Renmark · ROC 364596 · Last updated September 15, 2026
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What underlayment is, and why this is the job that matters
On a tile roof, the tile is not the waterproofing.
The tile is the weather surface. It sheds the bulk of the water, takes the sun and the hail, and shields what is below it. The layer that actually keeps water out of your house is the underlayment — the membrane fastened to the roof deck underneath.
Which means the practical life of a Valley tile roof is the life of its underlayment, not the life of its tile. Concrete and clay commonly outlast it by a wide margin. When the underlayment is finished, the correct job is usually a lift and relay: take the tile off, stack it, strip the old membrane, repair whatever decking is bad, install new underlayment, and put the same tile back.
You keep the tile. You buy the membrane and the labor. That is a fundamentally different purchase from a roof replacement, and it is the purchase a large share of Phoenix homeowners with twenty-year-old tile should actually be pricing.
The page ranking for this search is pricing a different roof
Search "roof underlayment cost Phoenix" and the head result is Angi's Phoenix underlayment page, updated August 2026. It publishes:
- $2 per square foot average, on a $1–$3 range
- $3,409 average project, on a $1,756–$4,339 range
Nothing on that page says "shingle." Nothing on it says "this excludes tile." But those figures describe underlayment replacement on a shingle roof — a job where the covering comes off and goes in a dumpster, not one where several tons of tile are removed by hand, stacked on the roof, and reinstalled piece by piece.
Compare it to every source that actually prices tile:
| Source | Scope | Per square foot | Whole roof |
|---|---|---|---|
| Angi Phoenix underlayment — Aug 4 2026 | Not stated; describes shingle | $2 avg ($1–$3) | $3,409 avg; $1,756–$4,339 |
| TSM Roofing — "underlayment only" | Tile | $3–$6 | Not published; $3–$6 across 2,000 sq ft is $6,000–$12,000, our arithmetic not theirs |
| TSM Roofing — "lift and reset" | Tile | $8–$12; states it "saves 30–40% vs full replacement" | — |
| Roof Repairs Phoenix AZ — "tile-over" (lift, replace underlayment, relay existing tile) | Tile | $5.50–$8.50 | 2,100 sq ft: $11,550–$17,850. 3,400 sq ft: $18,700–$28,900 |
A Phoenix homeowner with a tile roof who budgets from the head-ranking page is working from a number three to five times too low. They then receive a real quote, conclude that every roofer in the Valley is gouging them, and put the job off for another two summers. That is the actual damage.
Angi's Phoenix underlayment page is also the one place the company states its method plainly. It says it takes national average project costs and applies local price index data, drawn from the Bureau of Economic Analysis Regional Price Parities. That is national data with a regional multiplier. It is a legitimate estimating technique and it is not a survey of Phoenix roofs — which is worth knowing, because it also means the figure never had a chance to notice that Phoenix is a tile market.
One local page contradicts itself
TSM Roofing publishes, on a single page, "lift and reset" at $8–$12 per square foot and "underlayment only" at $3–$6 per square foot.
On a tile roof those describe the same job. The tile has to come off to get at the underlayment; there is no third way. Two labels, one operation, priced two to three times apart, in the same document. We are citing both because both are published — but if you are using TSM's numbers to check a quote, you should know you have a choice of two and no stated basis for picking either.
The same passage does not survive its own arithmetic either. It says lifting and resetting saves "30–40%" against full replacement at $10–$18 per square foot. At $8–$12 against $10–$18, the saving is roughly 20% to 33% at the midpoints, and 20% at the low end. The page's own numbers do not reach its own claim.
Check yours
$2 or $12 a square foot is not an answer. Get the number for your roof.
Nobody publishes how long underlayment lasts. Not one manufacturer.
If a storm is what prompted this, read what monsoon season actually does to a roof first — monsoon rarely causes underlayment failure. It reveals it.
The full version of this finding — all five manufacturers, what each one actually publishes, and how to judge your own roof without a figure nobody has — is on how long tile roof underlayment actually lasts in Phoenix heat.
This is the finding that changed how we talk about this job, and we want to be precise about it, because it is a negative finding and negative findings get overstated.
We went to the manufacturers — Polyglass, GAF, Owens Corning and Tarco — and read the published product data sheets for the underlayments commonly specified on Valley roofs, looking for a service life. None of them publishes one.
What they publish instead is a warranty, a maximum exposure window, and a temperature rating. Those are three different things, and none of them is a service life.
| Product | Warranty | Max UV exposure | Temperature rating |
|---|---|---|---|
| Polyglass Polystick MTS PLUS (SBS modified bitumen) | 1 year | "Max 180 days exposure" | "Approved up to 265°F" |
| Polyglass Polystick TU PLUS (tile-specific) | 2 years | "up to 180 days" | "Approved up to 265°F" |
| GAF Tiger Paw (synthetic) | "up to a Lifetime Limited Warranty" — conditional on GAF Lifetime shingles plus two qualifying GAF accessories | "resists UV degradation for up to 180 days" | Not given |
| Tarco asphalt-saturated organic felt (#15/#30) | "free from manufacturer's defects" only, with a disclaimer that statements are made "without guaranty, warranty or responsibility of any kind" | Not stated | Not given |
| Owens Corning DeckDefense | No term stated on the product page — it links a separate warranty document rather than publishing a duration | — | — |
Read the first two rows again. A one-year warranty. A two-year warranty. On the tile-specific product, two years — for a membrane that is about to be buried under several tons of concrete tile and expected to perform for decades.
That is not an accusation of a bad product. Polyglass publishes clear, specific, well-documented data sheets, which is why we can quote them at all. It is a statement about what the industry is willing to commit to in writing, and the answer is: far less than the homeowner assumes.
The 265°F rating is not a service life. It is a survivability figure — the temperature the product is approved up to. It says nothing about how many years of Valley sun cycling the membrane accumulates before it fails, and anyone who quotes 265°F at you as evidence of durability is either confused or hoping you are.
And this is a genuine blank, not a gap in our research: we could not find any published hot-climate or high-UV degradation rate for roofing underlayment, and no Arizona-specific service life from anyone. Not from a manufacturer, not from a trade body, not from a testing house. If someone quotes you "underlayment lasts X years in Arizona," ask where the figure comes from. We looked, and there is nothing to cite.
The only technical guidance that exists is twenty-one years old
The nearest thing to an authoritative statement on underlayment longevity comes from the National Roofing Contractors Association, and it is a principle rather than a number: the underlayment should match the primary roof covering's anticipated service life. Lighter products for shorter-life coverings; heavier products for durable coverings such as slate and tile.
That is Joan P. Crowe, AIA, then NRCA Manager of Technical Services, writing in Professional Roofing — "Underlayment considerations" — in May 2005. Twenty-one years ago. We are flagging the age because everyone should, and because nobody else quoting it does.
The same article notes that self-adhered modified bitumen is "more resistant to wrinkling and distortion and exhibit[s] better water-shedding properties than traditional asphalt-saturated felts."
The practical version: if your tile has decades left in it, the NRCA principle says the membrane under it should be specified accordingly — and that is a specification decision made on your quote, by product name, not an assumption you can make from the word "underlayment." Ask which product, which weight, and which manufacturer's data sheet it comes from.
No phone call
The 2026 Phoenix Door, Window & Roof Cost Guide
Every table on this page plus the tile, foam and replacement-cost equivalents, as a PDF.
How a relay actually works, and the two allowances that decide your final price
The sequence is simple and the money is in two line items nobody puts on a website.
- Tile is removed by hand and stacked, on the roof or on the ground.
- Old underlayment and fasteners are stripped off the deck.
- The deck is inspected — this is the first time anyone can see it.
- Damaged sheathing is replaced.
- New underlayment is installed, along with flashings, valley metal and any penetration details.
- The original tile is reinstalled, with new tile substituted for whatever broke.
Allowance one: deck repair. Nobody can price this from the ground and no honest quote pretends to. What a good quote does is state a rate per sheet of plywood and a quantity included in the base price, so that finding damage is a known unit cost rather than an open-ended change order negotiated while your roof is open.
Allowance two: tile breakage. Tile breaks coming down and going back on. This is normal, not negligence. One Phoenix source that prices the relay — Roof Repairs Phoenix AZ, on its "tile-over" page — expects 5% to 10% breakage. On a 3,000-tile roof that is 150 to 300 tiles that need replacing with matching stock.
So the two questions that actually separate relay quotes are: what breakage percentage is included, and what happens if your tile profile is no longer available. Ask both before anything comes off the roof. A bidder who has already checked availability for your specific profile and color has done work the others have not.
Permits: this is the job where Scottsdale differs
Most Valley jurisdictions exempt a same-material reroof from permit — seven of the eight we checked publish that exemption in their own adopted code, each traceable to a §105.2 exemption list.
Scottsdale is the exception, and a relay is precisely where its trigger fires. Scottsdale requires a permit "if any part of the roof sheathing or structural framing is either repaired and/or replaced," with three inspections: roof sheathing; flashing and felt; and final. On a lift and relay, replacing some deteriorated decking is routine. So an identical job can be permit-exempt in Phoenix and permitted with three inspections a few miles away.
Full code language for each jurisdiction, with the .gov sources, is on the Arizona roof replacement cost guide. We publish no permit fee figures anywhere on this site — we could not verify a fee schedule against a primary city document, and the fee numbers we found on roofing company pages carried no source at all.
Common questions
Frequently asked
- How do I know if I need underlayment replaced or a whole new roof?
- Tile condition and underlayment condition are assessed separately. Intact tile over finished underlayment is the classic relay case. Widespread cracked or spalling tile, an unobtainable profile, or badly deteriorated decking pushes it toward a full replacement — we cover those cases on the tile roof guide.
- How long does roof underlayment last in Phoenix?
- Nobody publishes a figure. We checked Polyglass, GAF, Owens Corning and Tarco: not one publishes a service life for underlayment. What they publish is a warranty — one year on Polyglass MTS PLUS, two on the tile-specific TU PLUS — a 180-day maximum UV exposure window, and a 265°F approval rating, which is a survivability rating rather than a lifespan. The only technical guidance available is NRCA's 2005 principle that the underlayment should match the covering's anticipated service life.
- Can I reuse my existing tile?
- That is the whole point of a relay, and normally yes. Expect some breakage — one Phoenix source that prices this work expects 5% to 10% — and confirm that matching replacement tile exists for your profile and color before the job starts.
- Why is one quote $2 a square foot and another $10?
- Usually because they are not pricing the same roof. The lower figures in circulation describe shingle underlayment, where the covering is torn off and thrown away. On tile, the covering is removed by hand, stacked, and reinstalled — that is the labor the low figures do not contain.
- Does new underlayment come with a warranty?
- The manufacturer's warranty is short and specific, and it is not the same as your contractor's workmanship warranty. Ask for both documents, by name, and ask how long each runs — they are almost never the same length, and the manufacturer's does not cover labor.
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