Tar paper siding, also called asphalt felt, is a flexible, paper-based sheet material saturated with asphalt and mineral granules. It is commonly installed under vinyl siding, wood clapboard, or cedar shingles to provide an extra layer of moisture protection.
As a weather resistant barrier, tar paper helps control condensation and prevents water from reaching sheathing and framing. Understanding how it works, how to install and maintain it, and how it compares to modern alternatives supports long lasting exterior performance.
Material Composition and Performance Characteristics
How Tar Paper Is Built and Why It Matters
The core of tar paper is a base of either fiberglass or organic paper mat, coated with asphalt to provide flexibility and water shedding capabilities. A top layer of small mineral granules reflects ultraviolet light, reduces surface temperature, and adds a slip resistant texture.
Because the material is relatively thin and flexible, it conforms well to framing, corners, and fastener paths. Proper overlap and detailing at edges, penetrations, and seams are essential to maintain its effectiveness as a continuous water control layer.
Side by Side Specification Comparison
Key Product Options and Typical Use Cases
| Product | Weight | Typical Use | Notable Features |
|---|---|---|---|
| 15 lb Standard Felt | 15 lb per 100 sq ft | Staple under siding, under lap siding | Lightweight, cost effective, easy to handle |
| 30 lb Heavy Duty Felt | 30 lb per 100 sq ft | Commercial walls, high wind areas, steep roof decks | Greater tear resistance, better moisture buffering |
| Modified Bitumen Membrane | Varied, often heavier | Modern exterior assemblies, below grade protection | Self adhering options, improved low temperature flexibility |
| Synthetic Housewrap | Varied, lighter than felt | New builds and retrofit weather resist barriers | Higher tear strength, breathability, longer handling life |
Historical Use in Residential and Commercial Construction
From Early Building Practices to Modern Code Requirements
Tar paper has been used in North American construction for more than a century, evolving from basic black felt to standardized products with defined weight classes and performance metrics. It gained popularity as builders sought a cost effective way to reduce air and water infiltration while meeting regional code expectations.
Over time, the industry shifted toward synthetic housewraps, but asphalt felt remains common in many markets, especially as a required underlayment for certain claddings. Today, building codes often specify minimum requirements for drainage planes, and tar paper can still satisfy those requirements when installed correctly.
Installation Techniques and Best Practices
Sealing, Overlap, and Fastening Details
Successful tar paper siding installations start with a continuous layer over the sheathing, carefully lapped horizontally so that water flows downward. Each course should overlap the one below by the distance recommended by the manufacturer and local code, typically several inches depending on exposure and wind conditions.
Use corrosion resistant fasteners designed for exterior use, spacing them appropriately to secure the material without overdriving into the sheathing. Sealant or flashing materials at windows, doors, roof lines, and other penetrations help maintain the intended drainage plane and reduce the risk of hidden moisture intrusion.
Maintenance, Lifespan, and Common Failure Signs
Inspection Routines and Long Term Care
Tar paper siding performs best when the building envelope is regularly inspected, especially after severe storms or during seasonal transitions. Look for lifted seams, missing granules, brittleness, and visible tears that could allow water to bypass the intended barrier path.
Addressing small issues early, such as replacing damaged sections or improving perimeter sealing, helps protect framing, insulation, and interior finishes. When combined with proper flashing and drainage details, well maintained tar paper can remain a reliable component of the wall system for many years.
Key Takeaways for Planning and Specification
- Confirm local code requirements for underlayment, overlap, and fastening details before specifying tar paper.
- Choose the appropriate weight and type based on exposure, climate, and the intended cladding material.
- Verify proper flashing, drainage planes, and moisture control measures during installation.
- Schedule periodic inspections to identify torn or displaced sections and address issues promptly.
- Combine tar paper with compatible sealants and flashing components for a durable, integrated water management strategy.
FAQ
Reader questions
Is tar paper siding suitable for exterior use in climates with high humidity?
Yes, when installed correctly with proper overlap and flashing, it acts as an effective water resistant barrier in humid climates, but it should be paired with drainage and ventilation strategies to reduce long term moisture buildup.
How does tar paper compare to modern synthetic housewrap in terms of durability?
Synthetic housewraps generally offer higher tear strength, longer UV resistance, and better breathability, while tar paper remains a cost effective option that still meets many code requirements when installed per manufacturer guidance.
What fasteners and underlayment methods are recommended for tar paper siding?
Use corrosion resistant nails or screws designed for exterior sheathing, spacing them according to manufacturer recommendations, and combine tar paper with proper flashing, sealants, and drainage planes for best results.
Can tar paper siding be painted directly, or does it require a specific finish treatment?
Tar paper is typically not painted directly; it is either left as is under other cladding or capped with a finish layer, because asphalt content can interfere with paint adhesion and long term appearance stability.