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Underlayment

The water-resistant layer installed directly over the roof deck beneath the shingles — the secondary line of defense that protects your home when the primary roofing material is compromised, and a line item that is frequently underspecified in Colorado insurance estimates.

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What Underlayment Is

Underlayment is the water-resistant or waterproof material installed directly over the roof deck — the OSB or plywood sheathing — beneath the shingles. It is the second line of defense in your roof system. When shingles are compromised by storm damage, age, or mechanical failure, the underlayment beneath them is what stands between the roof deck and water intrusion into your home.

Every asphalt shingle roof installation requires underlayment. It is not optional and it is not cosmetic — it is a structural component of the roof system that affects both waterproofing performance and code compliance. The specific type of underlayment required depends on your roof’s location, pitch, and the applicable building code, which in Colorado Springs is governed by the Pikes Peak Regional Building Department under the 2021 International Residential Code.

Types of Underlayment

Felt Paper (Tar Paper)

Traditional felt underlayment — commonly called tar paper — is made from organic or fiberglass mat saturated with asphalt. It comes in two standard weights: 15-pound and 30-pound, referring to the approximate weight per square. Felt paper has been used as roofing underlayment for decades and remains code-acceptable in many applications. Its limitations are significant, however. Felt paper tears easily when wet, wrinkles and buckles when exposed to moisture before shingles are installed, has limited resistance to wind uplift if the roof is left open during installation, and degrades faster than synthetic alternatives over the life of the roof. Many shingle manufacturers have moved away from recommending felt paper as their preferred underlayment product.

Synthetic Underlayment

Synthetic underlayment is manufactured from woven or non-woven polypropylene or polyethylene. It is significantly stronger than felt paper, more resistant to tearing and moisture, lighter to handle, and more stable when exposed to weather during installation. Synthetic underlayment does not wrinkle or buckle when wet, holds up better under foot traffic during installation, and typically carries longer manufacturer warranties than felt products. Most major shingle manufacturers now specify synthetic underlayment as their preferred or required product for warranty compliance. For Colorado roofs — where installation may span multiple days and afternoon thunderstorms are common — synthetic underlayment’s weather resistance during the installation window is a meaningful practical advantage.

Ice and Water Shield

Ice and water shield is a self-adhering, fully waterproof membrane — not merely water-resistant — used in the most vulnerable areas of the roof. Unlike felt paper and synthetic underlayment, which are mechanically fastened and rely on lapped seams for water resistance, ice and water shield adheres directly to the deck and seals around fasteners, creating a true waterproof barrier. It is required by Colorado building code at eaves in areas subject to ice damming, in valleys, and at other high-risk penetration and transition areas. It is typically used in combination with standard underlayment — ice and water shield in the code-required vulnerable zones, synthetic underlayment across the field of the roof.

Colorado Code Requirements

Under the 2021 IRC as adopted by the Pikes Peak Regional Building Department in Colorado Springs, specific underlayment requirements apply based on roof pitch and location.

For standard asphalt shingle roofs, a minimum of one layer of underlayment is required across the entire roof surface. On roofs with a pitch below 4:12, additional underlayment layers or a fully adhered membrane may be required depending on the specific application. Ice and water shield is required at eaves extending from the eave edge to a point at least 24 inches inside the interior wall line — which in Colorado Springs, at elevations above 7,000 feet in many areas, typically means a wider application than in lower-elevation jurisdictions. Ice and water shield is also required in all valleys.

For homes in Pueblo under the 2009 IBC as adopted by the Pueblo Regional Building Department, similar underlayment requirements apply with some variations in the specific ice and water shield coverage thresholds. Confirming the applicable requirements with your contractor before the permit is pulled ensures the estimate reflects what the inspector will require.

Underlayment and Storm Damage

Underlayment is affected by storm damage in two distinct ways — direct damage from storm impact and accelerated deterioration caused by compromised shingles above it.

Hail Impact Through Compromised Shingles

When hail impact fractures shingle mats and displaces granules, the exposed asphalt and weakened shingle structure no longer provide full protection to the underlayment below. Water that penetrates through bruised or cracked shingles reaches the underlayment layer. On older roofs where the underlayment has already degraded from age and UV exposure through granule-depleted shingles, storm damage to the shingles above accelerates the failure of the underlayment beneath. The combined condition — damaged shingles over deteriorated underlayment — is what makes storm-damaged older roofs so vulnerable to leaks after subsequent rain events.

Wind-Driven Rain

When wind lifts shingles — breaking seal strips and exposing the underlayment beneath — wind-driven rain can penetrate beneath the lifted shingles and saturate the underlayment. If the wind event is severe enough to hold shingles lifted for an extended period, or if the lifting occurs during a rain event, the underlayment absorbs that moisture. Felt paper underlayment that has been saturated loses much of its temporary water-resistance. The damage may not be immediately visible after the storm — but the compromised underlayment becomes an active leak pathway during the next significant rain.

Deteriorated Underlayment as Concealed Damage

On older roofs that have sustained storm damage over their lifespan, underlayment discovered during tear-off is frequently in significantly worse condition than the surface shingles suggested. Brittle, torn, and perforated felt paper that has been under hail-damaged shingles for years is a covered concealed damage item when its deterioration can be connected to storm-related water infiltration through the compromised shingles above. Documenting underlayment condition during tear-off — before it is discarded and replaced — is essential to supporting a supplemental claim for any underlayment-related items not included in the initial estimate.

Underlayment in Insurance Claims

Underlayment Specification in the Estimate

One of the most common and least-noticed discrepancies in Colorado insurance estimates is the specification of felt paper underlayment rather than synthetic. Xactimate, the software most carriers use to generate estimates, defaults in some configurations to felt paper pricing — which is meaningfully lower than synthetic. If your contractor is installing synthetic underlayment — which is now the industry standard and is required for warranty compliance by most major shingle manufacturers — the estimate should reflect synthetic underlayment pricing, not felt paper. The difference per square can be $10 to $20 or more, which adds up to a meaningful gap on a typical Colorado Springs roof.

Reviewing the underlayment line item in your insurance estimate and confirming it matches what your contractor is actually installing is a simple but worthwhile step before accepting the settlement.

Ice and Water Shield Coverage

Ice and water shield is priced separately from standard underlayment in Xactimate estimates and carries a higher per-square cost. The extent of ice and water shield coverage specified in the estimate should reflect the code requirements for your specific jurisdiction and roof configuration — not a minimal interpretation. At eaves, in valleys, around all penetrations, and at other code-required locations, ice and water shield should appear as a distinct line item at the correct square footage. When it is underspecified — particularly the eave coverage, which varies with jurisdiction and elevation — that is a supplement item worth addressing.

Underlayment as a Supplement Item

When tear-off reveals underlayment in significantly worse condition than expected — brittle, torn, or perforated felt paper rather than intact material — that condition supports a supplement for the uplift to synthetic underlayment if the initial estimate specified felt. It also supports documentation of the concealed damage finding for causation purposes. Photograph the underlayment condition during tear-off before it is removed, note the specific areas of deterioration, and include the condition in the written tear-off documentation that supports any supplement claims.

Common Underlayment Questions

Does my insurance have to pay for synthetic underlayment if my old roof had felt paper?

This depends on your policy’s coverage terms and your carrier’s position on like-kind-and-quality replacement. The strongest argument for synthetic underlayment coverage is that most major shingle manufacturers now require it for full warranty compliance — meaning felt paper underlayment with a manufacturer-warranted shingle system is not actually like-kind-and-quality because it voids the manufacturer warranty. A contractor letter confirming the manufacturer’s underlayment requirement for the specific shingle product being installed is the most effective support for this argument. Many carriers will accept synthetic underlayment pricing when this requirement is documented.

How do I know what underlayment is specified in my insurance estimate?

Look for the underlayment line items in your Xactimate estimate printout. The description will typically reference either felt paper — sometimes listed as “roofing felt” or “15 lb felt” or “30 lb felt” — or synthetic underlayment. A separate line item for ice and water shield should also appear at its own quantity and pricing. If you are not sure how to read your estimate, ask your contractor to review the underlayment specifications specifically and confirm whether they match what is being installed.

What is the difference between underlayment and ice and water shield?

Standard underlayment — whether felt paper or synthetic — is water-resistant, not waterproof. It sheds water effectively under normal conditions but is not designed to stop standing water or prolonged exposure to moisture. Ice and water shield is fully waterproof and self-adhering — it bonds directly to the deck and seals around every fastener penetrating it, creating a true waterproof membrane rather than a water-resistant barrier. Ice and water shield is used in the highest-risk areas of the roof where the standard underlayment’s water resistance is not sufficient.

Can underlayment failure cause interior damage even if the shingles look intact from the ground?

Yes — and this is one of the most common patterns in older Colorado roof claims. Shingles that look acceptable from ground level may have hail-bruised mats and granule displacement that allow water to reach a deteriorated underlayment layer below. The interior damage manifests as ceiling staining or wall moisture that appears to have no obvious source from the exterior. A professional inspection that evaluates both shingle condition and, where possible, underlayment condition provides the documentation needed to connect interior damage to the storm-compromised roof system above it.

How Claim Advocacy Helps With Underlayment Claims

Underlayment discrepancies in insurance estimates are among the most common and easiest to overlook — and correcting them requires knowing what to look for in the estimate before accepting the settlement.

  • Estimate specification review — confirming whether the underlayment line items in the insurance estimate specify felt paper or synthetic and whether the pricing reflects what is actually being installed
  • Ice and water shield verification — confirming that ice and water shield coverage areas in the estimate reflect the applicable code requirements for your jurisdiction and roof configuration
  • Tear-off documentation — photographing underlayment condition during tear-off before removal to document concealed deterioration that supports supplement claims
  • Manufacturer requirement documentation — obtaining contractor or manufacturer confirmation that synthetic underlayment is required for warranty compliance on the specified shingle product
  • Supplement preparation — submitting underlayment upgrade and ice and water shield supplements with supporting documentation at correct local pricing
  • Ice and Water Shield – The fully waterproof self-adhering membrane used in high-risk roof areas alongside standard underlayment
  • Synthetic Underlayment – The current industry standard underlayment that should be specified in any complete Colorado roof replacement estimate
  • Deck / Sheathing – The structural substrate that underlayment is installed over and protects from moisture
  • Concealed Damage – The category underlayment deterioration falls under when discovered during tear-off
  • Supplemental Claim – How underlayment specification discrepancies and concealed deterioration are corrected in the settlement

The underlayment specification in your insurance estimate is one of the easiest line items to overlook and one of the most straightforward to correct before accepting a settlement. A free inspection and estimate review confirms that every component of your replacement scope — including underlayment type and ice and water shield coverage — reflects what code requires and what your contractor is actually installing.

📞 (719) 210-8699
📧 gerald@winik.io

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