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 our 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 15 to 25 years in 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.

What a relay involves

1. Lift and stack. We remove the tile course by course and stack 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 we price replacement per tile.
2. Tear-off. Old felt, battens (if any), old valley metal, jacks and flashings come off to the bare deck. We inspect the deck and replace soft or delaminated sheathing per sheet.
3. New underlayment. Two layers of SBS-modified bitumen, or a synthetic underlayment specifically rated for tile and high heat, 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. Scottsdale requires a permit for underlayment replacement, and the inspector wants to see the underlayment before the tile goes back on. We schedule around it.

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. Tile roof underlayment replacement Scottsdale-wide 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 we will say so.

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

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; we do them in summer with dawn starts. Three to five working days on an average home. The house is dried in every night — we never leave more deck exposed than we can cover before we stop.