Roofing Systems and Materials: A Deep Dive for Insurance Claims

Our general roof damage article covers the basics of filing and fighting a roof claim. This companion article goes deeper into the roofing systems themselves — what they are, how they fail, and the specific claim issues each one creates. Understanding the technical differences between roofing materials is critical because insurers exploit policyholder ignorance of these details every day.

Roofing is an enormously broad subject with many rabbit holes. One article cannot cover everything, and this one does not try to. What it does cover are the roofing types you are most likely to encounter on a California property claim, the code issues that complicate replacement, and the specific disputes that arise when the roofing system itself becomes the battleground.

I. Residential Roofing Systems

Asphalt Composition Shingles

Asphalt composition shingles are the most common residential roofing material in the United States. They consist of a fiberglass mat coated with asphalt and surfaced with ceramic granules that provide UV protection and color. Standard architectural (dimensional) shingles carry manufacturer warranties of 25–50 years, though actual lifespan in California’s sun-intensive climate is often shorter.

Common claim issues:

• Granule loss.Wind and hail dislodge the protective granules, exposing the asphalt mat to UV degradation. Insurers frequently argue that granule loss is “cosmetic” and does not affect performance. This is often wrong — once the granules are gone, the exposed asphalt deteriorates rapidly, shortening the roof’s remaining life.
• Wind creasing and lifting. High winds can crease, lift, or tear shingle tabs. Insurers sometimes limit repairs to the visibly damaged shingles while ignoring adjacent shingles whose seal strips have been broken by the same wind event. A broken seal strip means the shingle will lift in the next windstorm, even if it looks fine today.
• Matching. Asphalt shingles change color lots, profiles, and product lines frequently. If half your roof is damaged and the replacement shingles do not match the undamaged half in color, profile, or weathered appearance, you may be entitled to a full roof replacement. See our matching guide for the legal standards.
• Cosmetic damage exclusions.Some policies contain endorsements that exclude “cosmetic” hail or wind damage to roofing. These endorsements are becoming more common and more aggressively applied. If your policy has one, read it carefully — the insurer must still pay for functional damage, and the line between cosmetic and functional is frequently disputed. See our hail damage science article for more on this distinction.

Wood Shake

Wood shake roofing — typically western red cedar — was extremely popular in California for decades. It provides a distinctive natural appearance and good insulation value. However, many California jurisdictions now restrict or prohibit new wood shake installations in wildfire-prone areas due to fire risk, and this creates a significant claim complication: when a wood shake roof is damaged, you often cannot replace it with the same material.

Common claim issues:

• Fire code restrictions. If your jurisdiction no longer allows wood shake and you must switch to a different roofing material, that triggers a code upgrade issue. This is where your ordinance and law coverage and code upgrade coverage become essential.
• Splitting, curling, and moss.Aged wood shakes split, curl, and develop moss growth. Insurers use this to argue that the roof was already at the end of its life and that the covered peril (wind, fallen tree) caused minimal additional damage. The reality is more nuanced — a properly maintained shake roof can last 30–50 years, and the age of the material does not eliminate the insurer’s obligation to pay for the damage caused by the covered peril.
• Matching. Replacing individual shakes to match weathered, decades-old cedar is essentially impossible. New cedar is a completely different color and texture than 20-year-old cedar. This is one of the strongest matching arguments in roofing.

II. Commercial and Flat Roofing Systems

TPO (Thermoplastic Polyolefin)

TPO is one of the most widely used commercial roofing membranes. It is a single-ply, heat-welded membrane available in thicknesses of 45 mil, 60 mil, and 80 mil (a mil is one-thousandth of an inch). TPO is popular because it is relatively inexpensive, reflective (white TPO easily meets cool roof requirements), and straightforward to install. A properly installed TPO system has a useful life of 20–30 years, with thicker membranes lasting longer.

Common claim issues:

• Seam failure. TPO panels are joined by hot-air welding. If the seams are not welded properly during installation, they can separate over time and leak. Insurers will argue this is a workmanship or maintenance issue, not a covered loss. However, if a covered peril (wind, hail, impact) damages a seam that was previously intact, the cause of the failure matters.
• Punctures and tears. TPO membranes are relatively thin. Foot traffic from HVAC technicians, dropped tools, and debris impacts can puncture the membrane. The insurer may argue that punctures are from maintenance activity (not covered) rather than storm debris (covered). Documentation of the timeline is critical.
• Membrane thickness disputes. When replacing a damaged TPO roof, the insurer may price the cheapest available thickness (45 mil) when the existing roof was 60 mil or 80 mil. The replacement should match what was there, or the insurer is under-scoping the claim.
• Accelerated weathering. Early generations of TPO (pre-2010) had formulation issues that caused premature cracking and shrinkage. Insurers will point to this as wear and tear. If a covered peril damaged a roof that was already experiencing accelerated weathering, the claim becomes a dispute over what portion of the damage is attributable to each cause.

EPDM (Ethylene Propylene Diene Monomer)

EPDM is a synthetic rubber membrane that has been used on commercial flat roofs for decades. It is a thermoset material — meaning its molecular structure cross-links during manufacturing, giving it excellent dimensional stability and the ability to recover its shape after temperature fluctuations. EPDM membranes are highly resistant to UV radiation and ozone, and a properly installed, fully adhered EPDM system can last 25–40 years or more.

Common claim issues:

• Shrinkage.EPDM membranes can shrink over time, pulling away from flashings, parapets, and penetrations. Insurers classify this as wear and tear. However, if a wind event tears a membrane that was already under tension from shrinkage, the wind is still a covered peril — the pre-existing condition may affect depreciation but does not eliminate coverage.
• Adhesive failure. Fully adhered EPDM systems rely on adhesive bonding the membrane to the substrate. If the adhesive fails, the membrane can billow and lift in wind, making it vulnerable to tearing. Mechanically fastened systems avoid this problem but have their own vulnerabilities at fastener points.
• Black vs. white.Traditional EPDM is black, which absorbs heat. White EPDM is available but less common and more expensive. California’s Title 24 cool roof requirements (discussed below) may require a white or coated membrane on replacement, adding cost that falls under code upgrade coverage.
• Seam tape vs. adhesive. Older EPDM systems used seam tape rather than liquid adhesive for joining panels. Taped seams have a shorter service life and are more prone to failure. If a storm exploits an aging taped seam, expect the insurer to blame the seam condition rather than the storm.

III. Metal Roofing Systems

Corrugated Metal

Corrugated metal roofing uses wavy or ribbed panels fastened to the roof structure with exposed screws or nails. It is common on agricultural buildings, warehouses, and some residential properties. Corrugated metal is durable against fire and rot but has specific vulnerabilities that create claim disputes.

• Exposed fasteners.The defining weakness of corrugated metal is its reliance on exposed fasteners — screws with rubber washers that penetrate the panel surface. Over time, the rubber washers degrade, the screws loosen or back out, and water infiltrates at every penetration point. In a wind event, panels with compromised fasteners are far more likely to lift and tear away. Insurers will argue the fastener deterioration is maintenance neglect; you will argue the wind caused the panel to fail.
• Hail denting.Corrugated metal dents visibly in hail events. Whether denting is “cosmetic” or “functional” depends on the severity. Severe dents can compromise the panel profile, creating ponding areas and reducing structural rigidity. Even shallow dents can crack paint coatings, leading to rust formation. If your policy has a cosmetic damage exclusion, this becomes a significant battleground.
• Rust and corrosion.Once the protective coating on corrugated metal is compromised — whether by hail impact, scratches from debris, or UV degradation — rust spreads rapidly. The insurer owes for the damage caused by the covered peril, including the accelerated corrosion that results from storm-inflicted coating damage.

Standing Seam Metal

Standing seam metal roofing uses interlocking panels with raised seams and concealed fasteners. It is a premium residential and light commercial system that is significantly more expensive than corrugated metal but dramatically more durable. Standing seam panels are typically lightweight steel or aluminum, and the concealed fastener design eliminates the penetration-point vulnerability that plagues corrugated systems. Standing seam systems are rated for winds of 140–180 mph, compared to 110–140 mph for corrugated panels.

• Higher replacement cost.Standing seam roofing costs significantly more than corrugated metal or asphalt shingles. If a standing seam roof is damaged, the insurer owes for a standing seam replacement — not a cheaper material. Watch for adjusters who price the replacement at corrugated metal rates or who try to substitute a lower-grade panel profile.
• Panel oil canning.Standing seam panels can exhibit “oil canning” — a wavy distortion in the flat area of the panel. This is generally a manufacturing or installation characteristic, not damage. Insurers sometimes cite pre-existing oil canning to argue that storm-caused panel distortion was already present.
• Matching and finish.Standing seam panels come in specific colors with factory-applied finishes (often Kynar/PVDF coatings). These finishes weather over time, and matching new panels to existing weathered panels can be difficult or impossible — creating a strong matching argument for broader replacement.
• Insurance premium benefits.Standing seam metal roofs often qualify for insurance premium discounts of 15–35% due to their superior wind and fire resistance. If an insurer tries to replace your standing seam roof with a lesser material, point out that doing so would also affect your future insurability and premium costs.

IV. California Title 24 Cool Roof Requirements

California’s Building Energy Efficiency Standards (Title 24, Part 6) require that roofing materials meet minimum solar reflectance and thermal emittance standards. The current standards — effective January 1, 2026 — are the most rigorous the industry has ever seen. These requirements apply to new construction and to re-roofing projects where 50% or more of the existing roof surface is being replaced.

The specific requirements vary by roof slope:

• Low-slope roofs (≤ 2:12 pitch): Aged solar reflectance of at least 0.63 and thermal emittance of at least 0.75.
• Steep-slope roofs (> 2:12 pitch): Aged solar reflectance of at least 0.20 and thermal emittance of at least 0.75.

Alternative compliance paths exist — for example, a home with at least R-38 ceiling insulation, a radiant barrier in the attic, or additional roof deck insulation of at least R-2 may be exempt. But the default requirement is a cool roof, and this has a direct impact on insurance claims.

V. Multiple Roof Layers

California building code limits the total number of roof covering layers to two. Building departments will allow a second layer of roofing to be installed over an existing layer, but will not allow a third layer. If your roof already has two layers and it needs to be re-roofed, all existing layers must be stripped down to the roof deck before new roofing can be installed.

This matters for your claim in several ways:

• Tear-off cost. Stripping two layers of roofing to the deck is significantly more labor-intensive and expensive than a simple overlay. The insurer must include the full tear-off cost in the estimate if a third layer is not permitted. If the adjuster prices a simple overlay when a full tear-off is required, the estimate is wrong and you should dispute it immediately.
• Deck inspection and repair. Once the existing roofing is stripped, the condition of the roof deck is exposed. Damaged, rotted, or deteriorated sheathing that was hidden under two layers of roofing will need to be replaced. This is additional cost that the insurer owes if the deck damage is related to the covered loss or was concealed by the roofing that had to be removed because of the covered loss. See our scope of loss guide for strategies on capturing these costs.
• Weight considerations.Two layers of asphalt shingles weigh approximately 5–7 pounds per square foot. Some older roof structures were not designed for this load. If the building department requires a structural evaluation after a tear-off reveals concerns, that additional engineering cost is part of the claim.
• Disposal costs.Removing two layers generates significantly more waste than one. The insurer’s estimate should reflect the actual volume of material being removed and disposed of, not a generic single-layer tear-off figure.

VI. Solar Panels and Roof Claims

Solar panels on a damaged roof create a unique set of complications that can significantly increase both the cost and the complexity of a roof claim. Here are the issues you need to understand:

Ownership and Coverage

Many residential solar systems are leased from a solar company rather than owned by the homeowner. When a storm damages the roof and the solar panels, the insurance company will often refuse to pay for the solar panel damage because the panels are owned by a third party — the solar leasing company. The insurer’s position is that the homeowner has no insurable interest in equipment they do not own.

This same principle applies in commercial settings. Restaurants, for example, often lease soda machines, ice makers, and other kitchen equipment. When a covered loss damages this leased equipment, the insurer may deny coverage for the same reason — the policyholder does not own it.

Detach and Reset: The Cost the Insurer Does Owe

Even when the insurer will not pay for damage to leased solar panels themselves, the cost of detaching and reattaching the panels to access the roof for covered repairs is typically a covered expense. The logic is straightforward: the insurer owes for roof repairs, and the panels must be removed to perform those repairs. The removal and reinstallation of the panels is part of the cost of repairing the roof, not a separate claim for the panels. Detach-and-reset costs typically range from $2,500 to $6,000 or more depending on the system size and complexity.

If the insurer refuses to include detach-and-reset costs in the roof repair estimate, push back. They cannot authorize a roof repair that is physically impossible to perform without removing the panels and then refuse to pay for removing the panels.

Additional Solar Panel Complications

• Matching under panels. Solar panels shade the roofing material beneath them, causing the covered and uncovered portions of the roof to weather differently. When the panels are removed for roof work, the color difference between the shaded and sun-exposed areas can create a matching dispute — the area under the panels may look significantly different from the rest of the roof.
• Ventilation. Solar panels affect roof ventilation by covering large areas of the roof surface and altering airflow patterns. After a roof replacement, the ventilation system may need to be reconfigured to account for the panels.
• Warranty issues.Both the roofing manufacturer and the solar panel installer may have warranties that are affected by the other’s work. A roofing contractor who reinstalls solar panels may void the solar warranty, and solar panel installation may void the roofing warranty. Coordinating these warranties adds complexity and cost to the project.
• Roof penetrations. Solar panel mounting systems require penetrations through the roofing material into the structural members below. These penetrations are potential leak points. When re-roofing, the penetrations from the old mounting system must be properly sealed or the deck repaired, and new penetrations made for the reinstallation. Insurers sometimes omit these costs from their estimates.

VII. Carrier Engineer Reports on Roofing

Insurers frequently retain forensic engineers to inspect damaged roofs and issue reports on the cause and extent of damage. These reports carry significant weight in the claims process, and unfortunately, many of them are written with the goal of minimizing the insurer’s exposure. Our guide to defeating carrier engineer reports covers this in depth.

Common problems with insurer-retained engineering reports on roofing:

• Attributing storm damage to “pre-existing wear and tear” or “manufacturing defects” without adequate testing or analysis to support the conclusion.
• Inspecting only a limited area of the roof and extrapolating conclusions about the entire surface.
• Using test methods or standards that are not appropriate for the roofing material in question.
• Minimizing the significance of damage — for example, characterizing functional damage as “cosmetic” or describing significant granule loss as “within normal parameters.”

VIII. Educational Resources

Roofing is a field where technical knowledge directly translates to claim outcomes. Two resources worth knowing about:

• Mathew Mulholland and the Building Experts Institute. Mulholland is a former roofing contractor turned Public Adjuster turned educator. He has purposely placed himself in the path of seven hurricanes with cameras and sensors to study how roofing systems fail, and he has designed and built his own hail cannon apparatus used in peer-reviewed research on hail damage to roofing and siding materials. His training programs through the Building Experts Institute are among the most technically rigorous available for understanding storm damage to roofing systems.
• Haag Engineering and Haag Education.Haag is a forensic engineering firm founded in 1924 that specializes in failure analysis of roofing and building materials. Haag’s education arm offers the Haag Certified Inspector (HCI) designation, which is widely recognized in the industry. A word of caution: Haag’s engineering reports and educational materials tend to favor insurance company positions. Their inspectors are well-trained, but the conclusions in Haag-affiliated reports often lean toward minimizing damage findings. Understanding Haag’s methodology is valuable precisely because you are likely to encounter their reports on the other side of your claim.

IX. Key Takeaways

• Every roofing system has specific vulnerabilities, and insurers exploit the technical details of each one. Know what type of roof you have and how it fails.
• California’s Title 24 cool roof requirements can force a material upgrade on re-roofing. This is an ordinance and law issue, and the increased cost should be covered under your code upgrade coverage.
• If your roof already has two layers, a full tear-off to deck is required before re-roofing. The insurer must pay for the full tear-off, not just an overlay.
• Wood shake over space decking requires new solid sheathing when converting to asphalt shingles — this cost is owed even without code upgrade coverage because it is physically necessary.
• Solar panel detach-and-reset costs are typically covered as part of the roof repair, even if the panels themselves are leased and not covered.
• Get your own roofing contractor’s inspection and estimate. Do not rely solely on the insurer’s adjuster or engineer, especially when the roofing system involves technical complexities they may not understand — or may choose to ignore.