Tile roof underlayment replacement in Scottsdale

Why the felt fails and the tile doesn't

Concrete and clay tile is essentially permanent in Arizona. It does not rot, UV does not bother it, and a properly laid tile roof sheds nearly all the water before it reaches the deck. What reaches the deck is stopped by the underlayment, and the underlayment on most Scottsdale tile roofs built from the late 1980s through the mid-2000s is one layer of 30-pound asphalt felt, or a 40-pound where the builder was generous.

Felt is organic paper saturated with asphalt. Under tile in this climate the air space between tile and deck runs 140–160°F on summer afternoons for four months a year. The asphalt oils cook off, the paper goes brittle, and at 15 to 25 years it cracks along every batten and every fastener. On the roof it looks like gray cardboard. Fold it and it snaps. The first monsoon with wind from the right direction finds a crack, and that is the leak.

Homeowners call the fix a relay, a re-felt or roof felt replacement; on a quote it usually reads as roof underlayment replacement. They are the same job.

What a relay involves

1. Lift and stack. The crew removes the tile course by course and stacks it on the roof or on pallets, sorted by condition. Broken tile is counted; typical breakage on a lift is 5–10% on concrete, more on old clay, and replacement is usually priced per tile.
2. Tear-off. Old felt, battens (if any), old valley metal, jacks and flashings come off to the bare deck. The deck gets inspected, and soft or delaminated sheathing is replaced per sheet.
3. New underlayment. Two layers of SBS-modified bitumen, or a synthetic underlayment specifically rated for tile and high heat (a self-adhered tile seal underlayment is one type), with a 20–30 year manufacturer rating. Not another single layer of 30-pound felt. This is the line to check on any quote.
4. New metal. Valley metal, headwall and sidewall flashing, pipe jacks, eave riser or drip edge, and new bird stops at the eave so pigeons stop nesting under the first course.
5. Battens and relay. New battens where the pitch requires them, elevated battens on low slopes so water drains under the tile, and the tile relaid with eave, rake and ridge courses secured. Broken tile replaced with matching profile from stock or salvage.
6. Ridge and hips. Reset with new mortar or foam adhesive and a vented ridge where the attic needs the air.
7. Permit and inspection. Check with the City of Scottsdale (or the Town of Paradise Valley, Town of Fountain Hills or Maricopa County, depending on the address) whether your job needs a permit and an inspection before the tile goes back on; most roofers pull it as part of the job.

What it costs

$8,000–$15,000 for most Scottsdale homes — a 2,000–2,800 square foot single-story with a 25–35 square roof. Larger two-story or custom homes in Paradise Valley and Troon with 50–70 squares, multiple levels and lots of valleys run higher. What moves the number: roof size, pitch and complexity, tile breakage (old clay two-piece mission tile breaks more than flat concrete), number of valleys and penetrations, and deck condition. A relay is typically 40–50% of the cost of a new tile roof, and the cost page shows both side by side.

When it's the right job — and when it isn't

Right when the tile is sound, the profile is available or the breakage is low, and the felt has failed or is about to. That is most tile roofs in Scottsdale between 15 and 30 years old.

Not right when more than 10–15% of the tile is cracked, the profile is discontinued and cannot be salvaged, or you want a different look — then a full replacement is the honest answer. Also not right when the felt is still good: a 12-year-old roof with a valley leak needs a repair, not a relay, and a good roofer will say so.

Signs your Scottsdale roof is near the end covers how to tell from the ground, and ten common roof problems puts the relay in context with everything else.

Common relay mistakes

• Reusing the old valley metal. It saves a few hundred dollars, it is hidden once the tile is back, and it is often where the next leak starts.
• Single-layer felt again. A quote that relays tile over one layer of 30-pound felt puts back the material that just failed.
• No bird stops. Without them, pigeons move back under the first course within a season.
• Breakage left vague. If the quote doesn't say how cracked tile is priced and matched, the job can stall on day two while someone hunts for a profile.
• Skipping the attic. Old stains on the underside of the deck predict how many sheets will need replacing; looking first keeps the deck allowance honest.

Getting the house ready

Clear patio furniture, grills and potted plants from under the eaves, because tile and debris come down along the edges. Move cars away from where the dumpster or tile pallets will sit. Take pictures off the walls on the side of the house being worked on; the hammering carries. If pool equipment or AC units sit near the eave, ask how they will be protected. Pets do better away from the noise on the tear-off days. Ask the crew lead for a short daily check-in so you know which slope is open each night.

Timing and the HOA

A relay does not change the look of the roof, so in almost every Scottsdale HOA there is nothing to submit. Best season is October through May; summer relays happen with dawn starts. Three to five working days on an average home. Ask the roofer to dry the house in every night, so no more deck is left exposed than can be covered before they stop.