House wrap, also known as weather-resistant barrier or WRB, is an essential component of a building’s exterior system. It provides an additional layer of protection against moisture and air infiltration. Many homeowners wonder if house wrap can be installed directly over old siding, as it may seem like a convenient solution. In this article, we will explore whether installing house wrap over old siding is a viable option and the potential implications of doing so.
Understanding House Wrap:
House wrap is intended to be installed on the sheathing of a building, which is typically made of plywood or oriented strand board (OSB). Its purpose is to prevent water from penetrating the exterior walls while allowing moisture vapor to escape, thereby protecting the building from mold, mildew, and rot. House wrap is usually made of a synthetic material, such as polyethylene or polypropylene, with microscopic pores that allow moisture to pass through while blocking bulk water.
The Importance of Proper Installation:
Before considering installing house wrap over old siding, it is crucial to understand that proper installation is key to its effectiveness. House wrap should be installed with meticulous attention to detail, ensuring that seams are properly sealed, and overlaps are correctly aligned. Failure to install house wrap correctly can result in the ineffective control of moisture and air infiltration, leading to potential damage to the building and reduced energy efficiency.
The Potential Issues:
While it may be tempting to skip the step of removing old siding and installing house wrap directly, there are potential issues that should be considered.
- Reduced effectiveness of house wrap: Installing house wrap over old siding can compromise its ability to control moisture and air infiltration effectively. The existing siding may already have some level of protection against moisture, but it is not designed to perform the same functions as house wrap. The extra layer of old siding can impede the proper functioning of the house wrap, potentially resulting in mold growth, rot, and reduced energy efficiency of the building.
- Trapped moisture: If there is already moisture trapped between the old siding and the house wrap, installing new house wrap over it can exacerbate the problem. Moisture trapped within the wall assembly can lead to extensive damage over time, such as wood rot, mold growth, and the deterioration of the structural integrity of the building.
- Structural concerns: Another issue to consider is the structural integrity of the building. If the old siding is damaged or deteriorated, covering it up with house wrap will only mask the underlying problem. It is necessary to address any issues with the old siding before installing house wrap to ensure the building’s structural stability.
The Recommended Approach:
To ensure the optimal performance of the house wrap and the longevity of the building, it is recommended to follow the proper installation procedures. The recommended approach is as follows:
- Removal of old siding: Before installing house wrap, it is advisable to remove the existing siding. This step allows for a thorough inspection of the sheathing, enabling any necessary repairs to be made and ensuring that the wall assembly is in good condition.
- Repairs and maintenance: While the old siding is removed, inspect the sheathing for any signs of damage or deterioration. Replace any damaged or rotted sections of the sheathing and address any other maintenance needs, such as caulking gaps and ensuring proper flashing installation.
- Installation of house wrap: Once the sheathing is in good condition, properly install the house wrap according to the manufacturer’s guidelines. Pay attention to overlapping seams, ensuring they are correctly aligned and securely sealed. Use an appropriate tape to seal the seams and around any penetrations, such as windows and doors.
- Reinstalling siding: After the house wrap is installed, the final step is to reinstall the siding. This could involve reusing the old siding if it is still in good condition or installing new siding. Follow the manufacturer’s recommendations for siding installation to ensure a proper fit and adequate ventilation.
While it may seem convenient to install house wrap over old siding, it is not recommended due to potential issues that can arise. Proper installation of house wrap requires removing the old siding, inspecting and repairing the sheathing, and following manufacturer guidelines. By taking the recommended approach, homeowners can ensure the optimal performance of their house wrap and protect their building from moisture intrusion, air infiltration, and other potential issues.