Choosing the right underlayment for your roof is crucial for its longevity and protection against leaks. While shingles form the visible, weather-resistant outer layer, a robust underlayment system sits beneath, providing an essential secondary defense against water damage. This comprehensive guide explores the different layers and materials found under shingles, helping homeowners understand the importance of each component.
What is Roof Underlayment?
Roof underlayment is a waterproof or water-resistant membrane installed directly on the roof deck before the shingles are applied. Its primary function is to act as a secondary water barrier, protecting your home's interior in the event of shingle failure or wind-driven rain. It also offers protection during the roofing process itself.
Types of Roof Underlayment
Several types of underlayment materials are available, each with its own advantages and disadvantages:
1. Felt Underlayment (Organic Felt)
This traditional option is made from asphalt-saturated organic fibers. It's relatively inexpensive, but it's less durable and susceptible to tearing and water absorption compared to newer materials. It's generally considered a less premium option.
2. Synthetic Underlayment
This modern alternative is made from polyethylene or polypropylene. It offers superior durability, tear resistance, and water resistance compared to organic felt. Synthetic underlayment is also lighter and easier to handle, making installation faster. Several types exist, including those designed for added strength and those with a self-adhesive backing.
3. Rubberized Asphalt Underlayment
This type combines the water resistance of asphalt with the durability of synthetic materials. It often provides superior protection against wind-driven rain and offers excellent tear resistance.
What is the Order of Layers Under Shingles?
The typical layering under shingles from the roof deck upwards is:
- Roof Deck: This is the structural base of your roof, usually plywood or OSB (Oriented Strand Board).
- Ice and Water Shield: In cold climates prone to ice dams, this is a crucial first layer, protecting vulnerable areas like valleys, eaves, and chimneys from ice buildup and water penetration. It’s a self-adhesive membrane.
- Underlayment: This is the primary waterproof layer, placed over the ice and water shield (if present) or directly onto the roof deck.
- Shingles: The final outer layer, providing weather protection and aesthetic appeal.
Why is Underlayment Important?
Investing in high-quality underlayment is crucial for several reasons:
- Secondary Water Barrier: It protects against leaks in case of shingle damage or failure.
- Wind Protection: It helps prevent wind-driven rain from penetrating the roof.
- Protection During Installation: It safeguards the roof deck during the roofing process.
- Increased Roof Lifespan: A good underlayment can contribute to the longevity of your roof.
How Long Does Roof Underlayment Last?
The lifespan of roof underlayment varies depending on the type. Synthetic underlayment generally lasts longer than organic felt. Check the manufacturer's specifications for specific durability information.
What are the Different Types of Shingles?
While not directly under the shingles, understanding shingle types is crucial for the complete picture of roof construction. Common types include asphalt shingles (3-tab or architectural), wood shingles, and tile. The type of shingle influences the necessary underlayment choices.
Is it Necessary to Use Underlayment?
While building codes may vary by region, using underlayment is highly recommended. It’s an essential element for a long-lasting, well-protected roof. Skipping this step significantly increases the risk of costly water damage.
How Much Does Roof Underlayment Cost?
The cost varies depending on the type and amount of underlayment needed. Consult with a roofing professional for accurate pricing based on your specific roof size and requirements. Remember that the cost of underlayment is a small fraction of the overall roofing project cost and the protection it provides is invaluable.
This guide provides a comprehensive overview of what lies beneath your shingles. Remember, consulting with a qualified roofing professional is crucial to ensure the correct materials and installation techniques are used for your specific roofing project and geographic location. They can assess your roof's condition and recommend the best underlayment for optimal protection and longevity.
