Repair or Replace? The Arizona Roof Decision Tree (With 3 Real Scenarios)

The repair vs replace question comes up on almost every inspection. We answer it the same way every time: look at four numbers, then look at the roof. Below is the framework plus three real 2026 jobs where the numbers told different stories.

The four numbers

1. Age of the underlayment (not the tile, not the shingle, the underlayment)
2. Cost of the repair as a percentage of the full replacement
3. Number of separate leak points in the last 3 years
4. How long you plan to own the home

The rules that fall out of it

• Underlayment older than 18 years + repair cost above 20 percent of replacement = replace
• Underlayment younger than 12 years + single leak point = repair
• 3+ leak points in 3 years = replace regardless of age
• Selling in under 3 years = repair unless a full replacement is required for inspection or insurance

Scenario 1: Chandler tract home, 22 years old

Single leak at a pipe boot. Repair quote $475. Full underlayment replacement quote $17,800. Owner staying 10+ years. Called it: replace. Why? Underlayment was 22 years old, past the 18-year threshold. The $475 repair would buy 6 months before the next boot or valley failed.

Scenario 2: Mesa home, 9 years old

Storm damage, 4 broken tiles, one boot cracked. Repair quote $685. Full underlayment replacement quote $16,200. Owner staying long term. Called it: repair. Underlayment is 9 years old, well inside the safe window. Repair for $685 plus a scheduled monsoon inspection every year.

Scenario 3: Ahwatukee foothills, 15 years old, selling in 18 months

3 separate leak repairs in the last 2 years, most recent one active. Owner listing in Spring. Called it: replace. The multiple leak points overrode the short ownership window. Buyer inspection was going to flag the felt anyway. Full replacement priced into the listing at $19,500, house sold in 11 days over ask.

How we present the numbers

Every inspection ends with a two-column report: cost of repair now plus expected life, versus cost of replacement plus expected life. You get both numbers. You decide. That is the standard.