The “25% Rule” for Roofing: What It Is, Where It Applies, and What Washington Actually Requires

Short answer: the “25% rule” is a Florida building-code provision, and it does not apply in Washington. It says that if more than 25% of a roof section is repaired or replaced within a 12-month period, the whole section has to be brought up to current code. It became famous because it forced Florida insurers into paying for full replacements after storms, and it was rolled back for hurricane-mitigated roofs in 2022. Homeowners in Spokane and the Tri-Cities see it in Google’s “People also ask” boxes because roofing questions travel nationally, not because it governs anything here.

What does govern a roof repair or replacement in Washington is a different set of rules: the state residential code’s reroofing section, your city’s permit requirements, and the terms of your own insurance policy. This guide covers each, in plain language, for Spokane, Spokane Valley, Richland, Kennewick and Pasco.

Where the 25% rule came from

The Florida Building Code’s roofing chapter said that when more than 25 percent of a roof or roof section was repaired, replaced or recovered within any 12-month period, the whole roof or section had to be made to conform to the current code. After the 2004 and 2005 hurricane seasons that meant tens of thousands of partial storm claims turned into full replacements, and the rule became a fixture of Florida insurance disputes. In 2022 Florida’s legislature (Senate Bill 4-D) removed the requirement for roofs built or replaced to the 2007 code or later, which is why articles about it read as both current and out of date. None of that ever crossed into Washington’s code, but the phrase spread nationally through insurance forums and roofing marketing, so the question now appears in Google’s “People also ask” boxes for Spokane and Tri-Cities roofing searches.

What Washington’s code says instead

Washington adopts the International Residential Code with state amendments, and its reroofing section (R908) is what your building inspector works from. The rules that matter to a homeowner:

• No more than two layers. A new roof cannot go over a roof that already has two or more layers of shingles; the old roofing has to come off. In practice, most Spokane and Tri-Cities contractors tear off regardless, because a roof-over hides the decking and caps the manufacturer warranty.
• Water-damaged or deteriorated roofing has to be removed, not covered. Rotten decking gets replaced (Alpine charges $95 per 4×8 sheet, agreed before it goes on).
• Ice barrier at the eaves in areas with a history of ice dams, which is all of eastern Washington. The City of Spokane inspects the ice-and-water shield before shingles go on.
• Repairs are exempt from a permit when they are minor (a handful of shingles, a pipe boot, flashing). Anything touching the decking or framing, and any full replacement, needs a permit in the City of Spokane, Spokane Valley, Spokane County, Richland, Kennewick, West Richland and Pasco. Each runs its own building department.

There is no percentage threshold in Washington that converts a repair into a mandatory replacement. Whether you repair or replace is a judgment about the roof, not a code trigger. Details by jurisdiction are in our Spokane roof permit guide and Richland roof permit guide.

What your insurer actually looks at in Washington

Because there is no 25% rule here, a Washington storm claim comes down to the policy language rather than the code. Three things decide what you get paid:

• Replacement cost vs actual cash value. Many eastern Washington policies now pay actual cash value on roofs past a certain age (often 15 to 20 years), which means the payout is depreciated. Check the roof endorsement on your declarations page before you file.
• Sudden damage vs wear. Wind, hail, falling trees and ice-dam damage are covered events. Granule loss, curling and age are not. The adjuster’s photos decide which bucket your roof lands in, so document the damage the day it happens.
• Matching. Washington has no matching statute, so an insurer can pay to repair one slope even if the new shingles will not match the rest. Whether they pay for the whole roof is a negotiation, and a contractor’s written scope showing why a partial repair will not perform is the strongest argument you can bring.

Alpine documents storm damage with photos, meets the adjuster on site and provides a line-item scope, and will tell you honestly when a claim is not worth filing (a denied claim can still count against you). Our roof insurance claim guide walks through the filing steps.

Repair or replace: the rule of thumb that does apply

Repair when the damage is in one area, the decking is sound and the roof is under about 15 years old. Replace when the roof is past 20 years, has two layers, needs a third patch in as many winters, or the damage spans several slopes. Most Spokane and Tri-Cities repairs run $200 to $1,500; a replacement runs $499 to $800 per square at published rates, or roughly $9,000 to $22,000 for a typical home. See Spokane roof repair pricing and the roof replacement cost calculator.

Frequently asked questions

What is the 25% rule for roofing?

A Florida Building Code provision: if more than 25% of a roof section is repaired or replaced within 12 months, the entire section must be brought up to current code, which in practice meant full replacement. Florida rolled it back for hurricane-mitigated roofs in 2022. It has never been part of Washington’s code.

Does the 25% roof rule apply in Washington State?

No. Washington follows the International Residential Code’s reroofing section: a two-layer maximum, removal of water-damaged roofing, ice barrier at the eaves, and a permit for full replacements and structural repairs. There is no percentage threshold that forces a replacement.

Will insurance replace my whole roof if part of it is damaged?

In Washington that depends on the policy, not the code. Insurers can pay to repair a single slope. A contractor’s written scope showing why a partial repair will not perform, plus photo documentation of the damage, is what moves a claim toward full replacement.

Can a new roof be installed over the old one in Washington?

Only if there is a single existing layer and it is not water-damaged. Most contractors tear off anyway, because a roof-over hides decking problems and limits the manufacturer warranty; CertainTeed’s 160 mph wind rating, for example, requires a tear-off.