When it comes to protecting a building from moisture, air leakage, and other external elements, house wrap plays a crucial role. It acts as a barrier, preventing water from infiltrating the walls, while also allowing moisture vapor to escape, ensuring proper insulation. One common question that arises is whether roofing felt can be used as a substitute for house wrap. In this article, we will explore this topic in detail and help you gain a clear understanding of the differences between house wrap and roofing felt and whether they can be interchangeable.
Understanding House Wrap
House wrap, also known as building wrap or weather-resistive barrier (WRB), is a material typically made of woven or non-woven polyethylene or other synthetic materials. It is installed on the exterior walls of a building before siding or other cladding materials are attached. House wrap acts as an additional layer of protection against air infiltration, water intrusion, and condensation inside the walls.
House wrap is designed with specific properties to fulfill its purpose effectively. It is typically vapor-permeable, meaning it allows moisture vapor to pass through while preventing liquid water from entering. Additionally, it serves as an air barrier, preventing air leaks that can decrease energy efficiency. House wrap is also UV resistant to protect against exposure from the sun.
An Overview of Roofing Felt
Roofing felt, also known as tar paper or underlayment, is a rolled material made of asphalt-saturated felt. It is primarily used as a water barrier beneath roofing materials, such as shingles or metal panels. Roofing felt helps prevent water from seeping through the roof and damaging the underlying structure. It also provides an additional layer of insulation and acts as a temporary protection during the installation process.
Differences Between House Wrap and Roofing Felt
While house wrap and roofing felt may have some similar characteristics, they serve different purposes and are not interchangeable. Here are some key differences between the two:
- Water Resistance: House wrap is designed to provide superior water resistance. It is specifically engineered to prevent liquid water from infiltrating the walls while allowing vapor to escape. On the other hand, roofing felt is not intended to provide the same level of protection against water intrusion. While it can shed water, it is not designed to be a primary moisture barrier.
- Vapor Permeability: House wrap is vapor-permeable, which means it allows moisture vapor to escape from the walls. This property is essential in preventing condensation and avoiding moisture-related issues. Roofing felt, however, is generally not vapor-permeable, as its primary function is to act as a water barrier.
- UV Resistance: Another significant difference is the UV resistance feature. House wrap is designed to withstand prolonged exposure to sunlight without degrading, as it is typically installed before the final cladding material is applied. In contrast, roofing felt is primarily installed beneath roofing materials and not exposed to UV rays once the roof has been completed.
While house wrap and roofing felt may have some similarities, they are not interchangeable. House wrap serves as a water-resistant and vapor-permeable barrier installed on the exterior walls, protecting against air and moisture infiltration. Roofing felt, on the other hand, acts as a water barrier beneath roofing materials and is not designed to provide the same level of water resistance or vapor permeability as house wrap. It is crucial to choose the right material for each specific application to ensure optimal protection and performance for your building.