Ember Vents ($1,100) vs. Class A Roof ($15K) by County Burn Probability: Payback Period in High-, Moderate-, and Low-Risk Zones
WildFireCost Team
Wildfire Risk Analyst
Your neighbor two counties over just told you a $1,100 vent upgrade cut their insurance bill by $630 a year. You did the same upgrade and your bill barely moved. Or maybe you're wondering whether it's worth doing at all, because your county doesn't look like a wildfire county.
Both can be true. Where your home sits on the county risk map decides how fast a hardening upgrade pays you back. The same retrofit can be a 21-month win in one zone and an 18-year slog in another.
This post breaks that down by county risk tier. It gives payback periods, 10- and 20-year NPV at a 5% discount rate, and an order to do the upgrades in. You'll need your own premium and your own hazard zone to finish the calculation.
Why this week's headlines matter for your county risk score
This week's insurance news is mostly not about wildfire, but it points at the same thing.
Insurance Journal reports that the remnants of Hurricane Polo are driving flood watches stretching from Phoenix to Dallas, with flash flooding already hitting parts of Utah and Nevada. That's a reminder that risk is local and layered. A county that ranks low for fire can rank high for flood. A county with a recent burn scar can rank high for both, because burned slopes shed water fast and can send debris flows downhill.
Insurance Journal also covers the owners of Camp Mystic proposing to sell their riverfront property in a bankruptcy plan after 27 campers and counselors died in a flood. It's a sobering example of a long-run cost of building and operating in a hazard corridor. I won't draw any wildfire parallel beyond one point: geography is the variable that doesn't change when you renovate. You can harden a structure, but you can't move it.
Two more stories say something about how carriers decide. Ascot Group named Mark "Sarge" Pepper president of global underwriting, effective October 1. Fed Vice Chair Michelle Bowman warned banks to prepare for AI-driven threats while noting the benefits of AI. Underwriting is leaning harder on data and models, and the location inputs to those models are county- and parcel-level hazard scores. That's why your county's tier matters.
The three tiers, and how we're using them
WildFireCost's analysis of 66,764 data points across ten sources includes:
- 6,290 records from the CAL FIRE Fire Hazard Severity Zone layer (calfire-fhsz)
- 3,144 county-level records from the USFS Wildfire Hazard Potential dataset (usfs-wildfire-risk)
- 21 rows of California Department of Insurance discount data (ca-cdi-insurance-discounts)
- 7 rows of IBHS hardening measure guidance (ibhs-hardening-measures)
- 290 rows of FAIR Plan data (ca-fair-plan)
One caveat before the math. The dollar amounts below are modeled scenarios, not filed rates. Actual discounts vary by carrier, and the CDI's Safer from Wildfires framework requires carriers to recognize certain mitigation steps but doesn't set one number for everyone. I've built three representative tiers so you can see how the math scales. Plug in your own quote when you have it.
| Tier | Typical setting | Modeled annual premium | Modeled mitigation discount |
|---|---|---|---|
| A: High burn probability | Very High FHSZ, WUI edge, FAIR Plan likely | $4,200 | $630 (15%) for vents + defensible space |
| B: Moderate | High or Moderate FHSZ, mixed WUI | $2,000 | $160 (8%) |
| C: Low | Little WUI, low USFS hazard potential | $1,200 | $60 (5%) |
The $4,200 and $630 figures for Tier A are the same ones we've used in our FAIR Plan mitigation credit analysis. The FAIR Plan is the state's insurer of last resort, and its premiums run high because your county's risk is already priced in.
Worked example: $1,100 ember vents by county tier
The upgrade: replace standard attic and crawlspace vents with ember- and flame-resistant vents. That's about $1,100 installed for a typical home. The defensible space part of the bundle is your own labor, so I'm counting it at $0 in cash.
Simple payback = cost ÷ annual savings
- Tier A: $1,100 ÷ $630 = 1.75 years (about 21 months)
- Tier B: $1,100 ÷ $160 = 6.9 years
- Tier C: $1,100 ÷ $60 = 18.3 years
NPV at 5%. The 10-year annuity factor is 7.7217, and the 20-year factor is 12.4622.
| Tier | Annual savings | PV of savings, 10 yrs | NPV after $1,100 | PV of savings, 20 yrs | NPV after $1,100 |
|---|---|---|---|---|---|
| A | $630 | $4,865 | +$3,765 | $7,851 | +$6,751 |
| B | $160 | $1,235 | +$135 | $1,994 | +$894 |
| C | $60 | $463 | –$637 | $748 | –$352 |
The takeaway is that ember vents are a clear win in Tier A, a marginal win in Tier B, and a poor insurance play in Tier C. In Tier C the vents may still be worth doing for safety. Just don't expect the insurance discount to pay for them.
This is the kind of analysis WildFireCost runs for you. It applies your zone and your premium, so you don't have to build the spreadsheet yourself.
The $15K Class A roof: same tiers, much slower
A Class A roof is the most fire-resistant roof rating, and it's often the most expensive item on a hardening list. Here I assume $15,000 for a full replacement and an incremental discount on top of the vent and defensible space credit. Those increments are $430 in Tier A, $190 in Tier B, and $70 in Tier C.
| Tier | Incremental savings | Simple payback | 10-yr NPV | 20-yr NPV |
|---|---|---|---|---|
| A | $430 | 34.9 years | –$11,680 | –$9,641 |
| B | $190 | 78.9 years | –$13,533 | –$12,632 |
| C | $70 | 214 years | –$14,459 | –$14,128 |
On insurance savings alone, the roof loses in every tier. That doesn't make it a bad purchase. Consider the situation where your roof is at end of life anyway. Then the relevant cost is the premium over a standard replacement, often $2,000 to $5,000 depending on material and region. At a $3,500 upgrade cost in Tier A, payback drops to 3,500 ÷ 430 = 8.1 years. That's a decent deal if you'll be in the home a decade.
The rule I'd use: don't replace a working roof to chase a discount. When the roof needs replacing anyway, pay the difference for Class A.
For more on this comparison, see our ember vents vs. Class A roof payback breakdown at a $4,200 premium.
Where does your home land? Reading the risk map
You need three inputs to place yourself in a tier.
1. Your fire hazard severity zone. CAL FIRE classifies California land as Moderate, High, or Very High. The calfire-fhsz layer we analyze has 6,290 records, and a parcel-level lookup is free on CAL FIRE's map. Outside California, look up your state forestry agency's WUI or hazard map.
2. Your county's burn probability. The USFS Wildfire Hazard Potential layer scores every U.S. county (our usfs-wildfire-risk dataset has 3,144 rows). It's a broad indicator. It tells you how your county compares to others, not whether your street will burn.
3. Your WUI status. The wildland-urban interface is where homes meet vegetation. Being inside the WUI often triggers building code requirements, such as California's Chapter 7A for newer construction, and it flags you to underwriting models. For the code side, see our guide to which Chapter 7A retrofits are mandatory vs. optional.
A quick self-test:
- Very High FHSZ, in the WUI, and quoted $3,000 or more or stuck on the FAIR Plan: you're likely Tier A.
- High or Moderate zone, some vegetation nearby, premium of $1,500 to $3,000: probably Tier B.
- No hazard zone designation and a premium under $1,500: likely Tier C.
Also, county averages hide a lot. Two homes in the same county can be in different tiers if one backs onto a canyon and the other sits in a subdivision. Use the parcel-level map, not the county headline.
The flood footnote: check this if you live downstream of a burn scar
Because of the Polo flood watches, one item deserves a place on your list. Standard homeowners policies exclude flood. Rain on a recent burn scar can cause flash flooding and debris flows, sometimes from storms that wouldn't have caused trouble before the fire.
If your property is downslope of a burn scar or sits in a drainage path, ask your agent about flood coverage. The National Flood Insurance Program typically has a 30-day waiting period, so it doesn't help if you buy it after the storm is in the forecast. Wildfire hardening doesn't change your flood exposure. The two risks are separate line items on your budget.
The prioritized action plan
Here's the order I'd follow, ranked by payback in a Tier A or upper Tier B county.
Step 1: Defensible space, starting with Zone 0 (0–5 feet). Cost: $0 to $300. Clear dead vegetation, remove combustible mulch next to the house, and move firewood and stored items away from walls. This is what IBHS Wildfire Prepared Home guidance and CAL FIRE both stress first, because embers ignite what's right next to the structure. It's also the item most homeowners skip. Then work outward to the 30- and 100-foot zones. Our defensible space maintenance checklist walks through it.
Step 2: Ember-resistant vents. Cost: about $1,100. In Tier A, this is the best-paying upgrade on the list, at 21 months and a 10-year NPV of about $3,765. Ask the contractor for documentation of the product rating and keep the invoice with photos. See our step-by-step vent guide for how to document it.
Step 3: Call your insurer and claim the discount. This step gets skipped constantly. Mitigation discounts generally aren't automatic. Send the documentation, ask the carrier or your agent which measures they credit, and get the new premium in writing. If you're on the FAIR Plan, ask about its mitigation credit.
Step 4: Small fixes. Cost: $200 to $1,500. Add 1/8-inch noncombustible mesh where needed, replace damaged roof edge gaps and flashing, and seal gaps in siding. These are cheap and address the same ember pathways.
Step 5: Class A roof, only at replacement time. If the roof has 3 to 5 years left, start collecting quotes. Compare the Class A upgrade premium, not the total cost.
Step 6 (Tier B and C): Re-run the numbers before spending. In Tier C, do the free items and skip the paid ones unless you want them for safety. In Tier B, vents are close to breakeven on savings, so decide based on your risk tolerance and how long you'll stay.
What could change your numbers
Three things move these tables.
Your actual discount. If your carrier gives 5% for vents, Tier A payback goes from 21 months to about 5.2 years. If it gives 20%, it's under 16 months. Get the number.
Your time horizon. If you plan to sell in 3 years, only Tier A vents clearly pay back. Buyers and their insurers may value the hardening, but don't count on a price premium.
Rate changes. Premiums have been rising in many fire-exposed markets. That helps payback if a fixed percentage discount applies to a larger premium. It can also mean discounts get renegotiated. That's another reason to lock in documented mitigation now.
Also, this whole analysis is about insurance savings. Hardening also reduces the probability that your home is lost. That value doesn't show up in the premium math, but it's real, and for many homeowners it's the main reason to do it.
The bottom line
- Tier A (high burn probability): ember vents pay back in about 21 months. Roofs don't pay back on insurance alone unless you were replacing anyway.
- Tier B (moderate): vents pay back in about 7 years. Do free steps first, then decide.
- Tier C (low): do free defensible space. Paid upgrades are for safety, not savings.
- Everywhere: the order is Zone 0 first, vents second, documentation third, roof last.
The math depends on your own premium and your own parcel's zone, and that's where a generic guide stops being useful. You can model your specific county, premium, and upgrade list at WildFireCost. Start with what you pay now and what your zone is, and see which upgrade comes out ahead for your home.
Data behind this post
The figures above are computed from the product's own reference tables, last refreshed 2026-03-29:
- 2 rows from bls-cpi-insurance
- 21 rows from ca-cdi-insurance-discounts
- 290 rows from ca-fair-plan
- 6,290 rows from calfire-fhsz
- 44,703 rows from census-zip-crosswalk
- 2 rows from fred-treasury-yield
- 7 rows from ibhs-hardening-measures
- 23 rows from icc-building-codes
- 12,282 rows from nifc-fire-perimeters
- 3,144 rows from usfs-wildfire-risk
Sources
- Flood Watches Stretch From Phoenix to Dallas on Polo Remnants — Insurance Journal
- People Moves: Brown & Riding Adds Moraru to Property Practice — Insurance Journal
- Camp Mystic Owners Seek to Sell Property as Legal Troubles Grow — Insurance Journal
- People Moves: Ascot Makes Executive Leader Moves, Organizational Updates — Insurance Journal
- Fed’s Bowman Touts AI Benefits, Risks for Bank Cybersecurity — Insurance Journal