When it comes to roofing, one crucial step is to ensure proper insulation and protection against moisture. Roofing felt, also known as tar paper or underlayment, is commonly used for this purpose. However, many people wonder whether it is appropriate to apply roofing felt directly over plywood. In this article, we will discuss the benefits and considerations to keep in mind when deciding to apply roofing felt over plywood.
Benefits of Roofing Felt:
Before delving into whether roofing felt can be applied over plywood, let’s understand the benefits it offers in general. Roofing felt acts as a protective layer between the shingles and the plywood, providing a range of advantages:
- Moisture Barrier: Roofing felt prevents any moisture from penetrating the plywood, thereby preserving its structural integrity.
- Protection Against Ice Dams: In colder climates, ice dams can form on roofs, leading to water backup. Roofing felt helps minimize the risk of water intrusion caused by ice dams.
- Temperature Regulation: Roofing felt can provide insulation, reducing heat transfer between the shingles and the plywood. This helps regulate indoor temperatures, reducing heating and cooling costs.
Considerations for Applying Roofing Felt over Plywood:
While roofing felt can offer several benefits, there are a few considerations to keep in mind when deciding to apply it directly over plywood:
- Roof Pitch: The pitch or slope of the roof is an essential factor to consider. If the pitch is less than 2:12, it is generally not recommended to apply roofing felt directly on plywood. In such cases, an additional layer of sheathing may be required to increase water resistance.
- Climate: The climate in which the roof is located plays a significant role in determining whether applying roofing felt over plywood is appropriate. In areas with high humidity or heavy rainfall, using roofing felt is highly recommended to avoid moisture damage.
- Building Codes: It is crucial to comply with local building codes and regulations. Some areas may have specific requirements for underlayment, including the use of roofing felt.
Steps for Applying Roofing Felt over Plywood:
If you have assessed the aforementioned considerations and decided to move forward with applying roofing felt over plywood, here are the steps to follow:
- Prepare the Plywood: Ensure that the plywood is clean and free of any debris. It should also be structurally sound and properly fastened to the roof deck.
- Start at the Bottom: Begin installing the roofing felt at the bottom edge of the roof, aligning it with the edge and allowing it to extend past the roof’s edge by a few inches.
- Overlap the Felt: As you work your way up the roof, overlap each subsequent row of roofing felt by at least 6 inches. This ensures proper water drainage and prevents any moisture from accumulating.
- Fastening the Felt: Secure the roofing felt to the plywood using roofing nails or staples, following the manufacturer’s guidelines. Ensure that the fasteners penetrate the plywood sufficiently without displacing it.
- Cut and Trim: As you approach any obstructions, such as vents or chimneys, cut and trim the roofing felt to fit around them, ensuring a proper seal.
Applying roofing felt over plywood can provide several benefits, including added protection against moisture and increased insulation. However, it is essential to consider factors such as roof pitch, climate, and building codes before deciding to proceed. Following the proper steps for installation will help ensure a successful roofing project while maximizing the longevity and durability of your roof. Always consult with a professional roofer for expert advice and guidance specific to your roofing needs.