Tar PaperEdit
Tar paper, commonly called roofing felt, is an asphalt-saturated sheet used to shield buildings from water where roofing and siding systems meet. It has long been a workhorse of construction, prized for its low cost, availability, and straightforward installation. The product comes in several forms, from traditional paper-backed felts to fiberglass-reinforced and self-adhesive variants, and it remains part of a broader system of moisture control in both roofing and wall assemblies.
The history and purpose of tar paper lie in simplicity and practicality. Early builders used tar or pitch-coated papers as a basic moisture barrier beneath shingles, tiles, or siding. Over time, manufacturers refined the product, introducing asphalt-saturated paper and then reinforcing materials such as fiberglass to improve tear resistance. In many parts of the world, tar paper is still chosen for its affordability and familiar performance, especially on projects where speed and economy matter. While the traditional form is often called roofing felt, the term can also cover newer, reinforced products designed for longer life and easier installation. In some older installations, asbestos-containing felts were used, a fact that matters for handling and abatement today; today’s felts are designed to be asbestos-free, but historical records and legacy homes may still raise questions about safety and materials history. See asbestos for context on historical building practices.
Composition and History
Tar paper is made by coating or saturating a base substrate with asphalt or bitumen. The base can be plain paper or a fiberglass mat, and the asphalt provides a waterproof barrier that remains flexible enough to bend with roof pitches and wall contours. The common nomenclature of felts is tied to weight, typically expressed as pounds per 100 square feet (for example, 15-lb, 30-lb, or 60-lb felts). A heavier felt generally offers greater tear resistance and longer potential life under the roof or wall assemblage, though the overall performance also depends on correct installation and shelter from weather exposure.
Modern tar paper products diversify beyond the classic paper-backed version. There are:
- Paper-backed felts (basic, often in 15-lb or 30-lb varieties) for traditional installations. See roofing felt.
- Fiberglass-reinforced felts (higher tear strength and puncture resistance) that come in comparable or greater weight classes.
- Self-adhesive underlayments (peel-and-stick) that provide an easier, weather-tight seal in some conditions.
- Synthetic or synthetic-reinforced felts that are designed to combine ease of handling with enhanced durability.
For roof applications, tar paper functions as an initial moisture barrier beneath the final roof covering, such as asphalt shingles; for wall systems, it has historically served as a weather-resistant barrier behind siding and underlayment. The shift toward house wraps and other modern barriers in many markets has led to a spectrum of choices, but tar paper remains a familiar option in many builds. See roofing felt, house wrap and construction for related concepts.
Types and Installation
- Traditional paper-backed felts: Installed with overlaps that shed water toward the lower edge and with fasteners that secure the layer to roof decking or wall sheathing. The weight designation (15-lb to 30-lb) helps builders gauge tear resistance and handling characteristics.
- Fiberglass-reinforced felts: These provide greater rupture strength, which is beneficial on steeper roofs or harsher climates.
- Self-adhesive underlayments: These employ a pressure-sensitive adhesive surface covered by a release liner; installation usually requires clean, dry surfaces and proper temperature conditions to ensure adhesion.
Weather considerations: Tar paper should be installed according to manufacturer instructions and local codes. In roofing, installation typically proceeds from the bottom edge up, with appropriate overlaps to protect against wind-driven rain. In some zones, longer exposure of the bare underlayment is avoided by promptly installing the final roof covering, which reduces the risk of UV degradation.
Weather and surface prep: A clean, dry surface is essential for proper adhesion (for self-adhesive types) and for secure nailing or stapling in non-adhesive varieties. In cold weather, installation considerations may shift toward products rated for lower temperatures, as adhesives and some underlayments perform differently in the cold. See installation and roof for broader guidance.
While tar paper is straightforward to work with, it is not a universal solution. Some builders now favor synthetic or rubberized underlayments for higher tear resistance, quicker installation, and improved performance in wet conditions. See synthetic underlayment and underlayment for comparisons.
Performance, Durability, and Practical Considerations
Tar paper is designed to provide a passive moisture barrier that works in concert with a roof or wall system. Its effectiveness depends on proper installation, integration with other layers, and protection from prolonged UV exposure before top coverings are complete. Once covered by shingles or siding, the underlayment is largely shielded from direct weather, which helps extend its functional life.
Durability varies by product type and climate. Heavier felts and fiberglass-reinforced varieties tend to resist tearing and punctures better than lighter, plain-paper felts. However, all underlayment products have finite lifespans, and performance hinges on correct installation and maintenance. Over time, moisture intrusion, heat, and aging can degrade any barrier, which is why many building codes and manufacturers emphasize proper installation details and timely roof or siding replacements.
Asbestos-related concerns come up with older structures. Some vintage tar-paper products used in the past contained asbestos fibers as part of their reinforcement. While modern felts are formulated to be asbestos-free, awareness about potential legacy materials is prudent in restoration projects. See asbestos for more background.
Environmental and economic considerations also shape discussions about tar paper. It is a petroleum-derived product, so proponents of traditional methods often argue that it offers a cost-effective, locally available option that can be repaired or replaced with familiar tools and practices. Critics point to alternatives with improved tear resistance, reduced weight, or greater long-term performance in extreme conditions, leading to ongoing debates about the best balance of price, performance, and labor. See construction, asphalt and bitumen for related context, and consider green building perspectives if evaluating environmental factors.
Contemporary Debates
- Traditional vs. modern underlayments: Advocates of traditional tar paper emphasize cost, familiarity, and the track record of performance when used correctly. Proponents of newer synthetics argue that higher tear resistance, longer lifespans, lighter weights, and easier handling justify the switch in many projects. See underlayment and synthetic underlayment for side-by-side comparisons.
- Moisture management vs. cost: Tar paper offers a straightforward moisture barrier at a low price point, which suits many budget-conscious builds. Critics contend that advanced barriers can improve long-term performance in areas with heavy rainfall, humidity, or wind-driven rain.
- Environmental and health considerations: The shift away from asbestos-containing felts in older homes reflects health concerns and modern safety standards. Contemporary tar papers emphasize minimal environmental impact relative to their function, but debates continue about embodied energy, recyclability, and the trade-offs between cost and sustainability. See asbestos for historical context and environmental impact discussions in building materials.