Searching for roofing felt for sale can bring up rolls with different weights, standards, widths, and intended uses. The right choice depends on the roof covering, roof slope, local building code, and installation conditions—not just the lowest price. This guide explains how roofing felt works, how to compare products, and what to check before buying for a U.S. roofing project.
What Roofing Felt Is
Roofing felt is a sheet underlayment installed over roof decking and beneath shingles or other approved roof coverings. Traditional felt is made by saturating a fiber base with asphalt. It provides a secondary layer that can help protect the roof deck from water during construction and from limited moisture intrusion after installation.
Roofing felt is also commonly called felt underlayment, asphalt-saturated felt, roofing paper, or tar paper. “Tar paper” is a familiar informal name, but modern products are generally asphalt-based; buyers should rely on the product label and technical data sheet rather than the nickname.
Felt is not a substitute for shingles, flashing, or a properly designed water-shedding roof. It is not intended to make an improperly installed roof waterproof. Its performance depends on suitable materials, correct fastening, proper laps, and compliance with the roofing-system instructions and applicable code.
Types of Roofing Felt for Sale
15-Pound and 30-Pound Felt
Traditional products are often marketed as 15-pound or 30-pound felt. These names reflect historical product categories, not necessarily the exact weight of a current roll. Product construction and actual coverage can vary, so compare the manufacturer’s specifications, standard designation, roll dimensions, and coverage instead of assuming that a “30-pound” label guarantees a particular performance level.
In general, heavier traditional felt is thicker and may be more resistant to handling damage than lighter felt. That does not make it automatically suitable for every roof. The roof covering manufacturer’s instructions and local code determine what underlayment is acceptable for a particular assembly.
ASTM-Specified Asphalt-Saturated Felt
Labels may reference standards such as ASTM D226 or ASTM D4869. These standards identify requirements for particular types of asphalt-saturated roofing felt. A product’s compliance claim should be confirmed on its packaging or technical documentation. Standards are useful for comparing products, but they do not replace the roofing-system requirements or local code provisions.
When a project specification calls for a particular ASTM standard or felt type, match that language carefully. A product that looks similar or has a familiar weight designation may not meet the specified requirement. Contractors and homeowners can ask the supplier for the product data sheet if the package does not clearly state the standard.
Synthetic Underlayment
Synthetic underlayment is a separate category, commonly made with woven or nonwoven polymer materials. Many synthetic products are lighter per unit of coverage, resist tearing during handling, and have printed installation guides. Their grip, exposure limits, fastening methods, and weather resistance vary by product.
Synthetic material is not roofing felt in the traditional asphalt-saturated sense. It may be a suitable alternative where the roof covering manufacturer and code allow it, but it should not be substituted automatically when a specification calls for asphalt felt. Compare approved uses, not just the product name or roll price.
How to Choose the Right Roofing Felt
Start With the Roof Covering
The roof covering affects the underlayment choice. Asphalt shingles, metal panels, tile, and other materials can have different installation requirements. Some manufacturers specify a particular underlayment, fastening pattern, or additional layer for certain roof designs. A product approved beneath one covering may not be approved beneath another.
Check the covering manufacturer’s installation instructions before purchasing. The underlayment may also need to be compatible with special components such as ice-barrier membranes, valleys, low-slope areas, or metal roofing systems. If the roof is part of a manufacturer-backed system or warranty, use the listed materials and follow the stated installation conditions.
Confirm Roof Slope and Local Code
Roof slope can affect the required underlayment arrangement. The International Residential Code includes underlayment provisions for various roof coverings, but the code edition adopted—and any local amendments—can differ by jurisdiction. A building department may also apply requirements based on the project location, roof design, or permitting conditions.
For example, cold-climate areas may require an ice barrier at eaves under adopted code provisions, while other locations may have different rules. That barrier is a separate product from ordinary roofing felt. Before buying, verify the current local requirements with the building department or a qualified roofing professional, especially for a permitted reroof or new construction project.
Consider Weather and Installation Conditions
Felt can wrinkle, tear, or become slippery when wet, and it should not be left exposed beyond the product’s stated exposure limit. Installation timing matters: underlayment is typically part of a layered roof system, not a long-term finished surface. If rain is likely during construction, discuss temporary protection and sequencing with the installer.
Temperature can affect how easily some materials unroll and lie flat. Wind exposure also matters because loose sheets can lift before the roof covering is installed. Use the specified fasteners and fastening pattern, and avoid walking on wet or loose underlayment. Roofing work carries serious fall risks; appropriate fall protection and safe access are essential.
How Much Roofing Felt to Buy
Estimate the roof area rather than using the home’s interior floor area. Roof area changes with slope, overhangs, dormers, valleys, and other features. A contractor can measure the roof directly or calculate an estimate from building dimensions and roof geometry.
Roll coverage is listed by the manufacturer, but the net installed coverage is lower than the sheet’s raw dimensions because courses overlap and details create waste. The amount needed also depends on the roof layout and installation method. Use the product’s coverage information and allow for the project’s actual overlaps, cuts, and damaged material.
A basic planning approach is:
- Determine the roof surface area, including relevant overhangs and separate roof sections.
- Check the selected roll’s stated coverage and required lap dimensions.
- Account for valleys, hips, ridges, penetrations, and cuts that reduce usable coverage.
- Ask the supplier or installer to confirm the order quantity before purchase.
Buying too little can delay work and create color or product-lot differences if a later replacement roll is needed. Buying substantially more than necessary can leave unused material that may be difficult to return, particularly if opened or weather-damaged. Confirm return policies and storage requirements before ordering.
Comparing Roofing Felt Prices
The price of roofing felt for sale varies with product type, roll size, thickness, brand, certification, and region. A low price per roll is not always the best value if the roll covers less area or does not meet the project specification. Compare cost per usable square—a roofing square is 100 square feet—using the manufacturer’s stated coverage and installation overlaps.
When comparing quotes, check whether the price includes delivery, sales tax, or other materials. Roof underlayment is often purchased alongside cap nails or other specified fasteners, flashing, and ice-barrier membrane. These are not interchangeable items, and a quote that includes only felt may not represent the full material cost.
| What to Compare | Why It Matters |
|---|---|
| Product type and standard | Confirms the material matches the roof specification. |
| Roll dimensions and coverage | Shows how much roof area the purchase can cover after laps. |
| Exposure and weather limits | Helps determine how the material can be staged during installation. |
| Fastening instructions | Ensures the chosen fasteners and pattern suit the product. |
| Delivery and return terms | Clarifies total cost and options for unused or damaged rolls. |
Where to Buy Roofing Felt
Roofing felt is commonly available through roofing-material distributors, building-supply stores, and home-improvement retailers. Online suppliers may offer a wider selection, but buyers should verify shipping charges, roll dimensions, delivery access, and whether the product is sold by the roll, bundle, or pallet.
Local roofing suppliers can be useful when a project has a specification to meet. They may help identify compatible products and arrange delivery to a job site. For a small repair, retailers may carry convenient quantities, but the repair still needs to match the existing roof system and manufacturer guidance.
Before placing an order, confirm the exact product name, standard, roll size, quantity, and condition. Ask whether the rolls have been stored dry and protected from damage. Keep receipts and product documentation, particularly for permitted work or a roof installation covered by a manufacturer’s warranty.
Installation and Storage Basics
Roofing felt should be installed over a clean, sound roof deck, following the product instructions and applicable roofing requirements. Courses are generally arranged to shed water, with the required overlaps and fastening details specified by the manufacturer or project documents. Openings, edges, valleys, and transitions need careful detailing; felt alone does not replace flashing.
Do not assume every felt product uses the same fasteners or exposure limits. Some instructions may call for roofing nails or cap fasteners, while other systems specify different details. Follow the printed instructions for the selected roll, including how to handle laps and whether the material may be temporarily exposed.
Store rolls in a dry, protected location and handle them as directed. Avoid leaving materials exposed to rain, standing water, or conditions that could cause damage before installation. If a roll is torn, soaked, contaminated, or has unclear labeling, consult the supplier or manufacturer rather than installing it by guesswork.
Common Buying Mistakes to Avoid
- Choosing by price alone: A cheaper roll may not meet the required standard or provide the expected coverage.
- Confusing felt with ice-barrier membrane: These products serve different roles and are not automatically interchangeable.
- Ignoring the roof-covering instructions: The shingle or panel manufacturer may set specific underlayment requirements.
- Assuming weight names are exact specifications: Check the actual standard, product data, and roll coverage.
- Ordering based only on house size: Roof slope, overhangs, and layout affect the quantity needed.
- Leaving underlayment exposed too long: Follow the product’s stated exposure and weather limitations.
Reliable Sources for Product and Code Checks
For a specific project, the most useful references are the underlayment manufacturer’s technical data sheet, the roof-covering manufacturer’s installation instructions, and the locally adopted building code. The International Code Council publishes model codes, but local jurisdictions determine which editions and amendments apply. Product standards such as ASTM specifications should be checked against the exact product documentation.
Roofing-industry guidance from organizations such as the National Roofing Contractors Association can provide broader context, while a qualified local roofer can evaluate the roof’s condition and installation requirements. If the project involves structural damage, extensive leaks, or complex roof details, professional assessment is safer than selecting materials by search result alone.