What Goes Under Shingles on a Roof? A Comprehensive Guide
A roof is more than just its attractive outer layer of shingles. Understanding the components beneath is crucial for ensuring a durable, weather-resistant, and long-lasting roof. This comprehensive guide will detail the layers found under your shingles, answering common questions homeowners have about this often-overlooked aspect of roofing.
What is the purpose of the underlayment?
The primary purpose of underlayment is to provide an extra layer of protection against water damage. It acts as a secondary water barrier, safeguarding your home even if your shingles are compromised by wind, hail, or other damage. Without it, water could easily penetrate the sheathing and cause significant structural issues. There are various types of underlayment, each with its own properties and benefits.
What are the different types of underlayment?
Several types of underlayment exist, each serving a unique purpose:
- Felt Paper (Organic Underlayment): This traditional, asphalt-saturated material is relatively inexpensive but less durable and water-resistant than synthetic options. It’s still used, particularly in budget-conscious projects.
- Synthetic Underlayment: Made from polypropylene or other polymers, this offers superior water resistance, tear strength, and longevity compared to felt. It often comes with a self-adhesive backing for easier installation. Many consider this a better investment in the long run, despite its higher initial cost.
- Rubberized Asphalt Underlayment: This blends asphalt with rubber to enhance durability and water resistance, offering a good balance between cost and performance.
What is the role of roof sheathing?
Beneath the underlayment lies the roof sheathing, which provides structural support for the entire roofing system. This is usually made of plywood or oriented strand board (OSB), forming a continuous surface that distributes the weight of the roof and protects the home’s interior. The sheathing must be properly installed and secured to ensure the roof's structural integrity. Any gaps or damage here can compromise the entire roof’s performance.
Is there anything else under the sheathing?
Yes, under the sheathing, you'll typically find the roof trusses or rafters, which form the actual structural framework of the roof. These are the load-bearing members that support the weight of the sheathing, underlayment, shingles, and any other roofing materials. Inspecting these members for damage is critical during a roof inspection.
What about ice and water shield?
Ice and water shield is a specialized underlayment often installed in vulnerable areas like valleys, chimneys, and along the eaves. This highly waterproof membrane protects against ice dams and leaks in these areas prone to water accumulation.
How do I know what's under my shingles?
If you're unsure about the specific materials used on your roof, a qualified roofing professional can perform a thorough inspection. They can identify the types of underlayment, sheathing, and other components, helping you assess the condition of your roof and plan for any necessary repairs or replacements. This inspection is invaluable for understanding your roof’s composition and ensuring its longevity.
By understanding the layers beneath your shingles – from the underlayment and sheathing to the structural framework – you'll gain a deeper appreciation for the complexity and importance of a well-constructed roof. Remember, a properly installed and maintained roofing system is essential for protecting your home from the elements.
