Adding flashing around a window is a critical step during installation to protect your home from water damage. It involves preparing the rough opening and applying layers of protective materials before and after the window unit is set in place.
Here are the key steps based on standard practices and the provided reference:
Preparing the Rough Opening
Proper preparation ensures the flashing can create a tight seal. This includes dealing with the existing weather resistive barrier (WRB), often house wrap, around the opening.
- Cut Back WRB: The first step is to carefully cut back the WRB surrounding the window opening. This allows for the proper layering of flashing materials.
Installing Sill Pan Flashing
The sill, or bottom of the window opening, is particularly vulnerable to water entry. Sill pan flashing provides a drainage plane.
- Install Sill Pan Flashing: Install a continuous piece of flashing material, often shaped like a pan, along the bottom of the rough opening. This directs any water that gets behind the window frame outwards, preventing it from pooling and causing rot.
Preparing Side and Head Areas
Before installing the window, you need to prepare the sides of the opening.
- Wrap Side WRB Panels: With the sill pan flashing in place, wrap the side panels of the WRB (which you cut back earlier) around into the interior of the rough opening. Secure them appropriately. This creates a continuous layer around the sides. (Note: Head flashing is typically installed after the window unit, overlapping the side flashing).
Applying Sealant
Sealant acts as a crucial adhesive and barrier to complement the flashing.
- Apply Sealant: Apply a continuous bead of high-quality sealant (compatible with your flashing and window materials) in the appropriate locations on the rough opening before setting the window unit. This typically includes the sill and sometimes up the sides.
Installing the Window Unit
With the opening prepared and sill flashing/sealant in place, the window unit can be installed.
- Install Window Unit: Carefully lift and set the window unit into the prepared opening, pressing it into the bead of sealant on the sill and aligning it correctly. Secure the window according to the manufacturer's instructions.
Post-Installation Steps
After the window is secured, finishing touches are added to ensure energy efficiency and further sealing.
- Insulate Around Window Unit: Fill the gap between the window frame and the rough opening with appropriate insulation material, such as low-expansion spray foam or fiberglass. While insulation isn't flashing itself, it's a vital part of creating a weather-tight and energy-efficient installation.
Summary of Flashing Steps:
| Step | Action | Purpose |
|---|---|---|
| Preparation | Cut back WRB | Prepare opening for flashing layers |
| Sill Protection | Install sill pan flashing | Create drainage plane at bottom |
| Side Preparation | Wrap side WRB panels | Prepare sides for layering |
| Sealing | Apply sealant | Create adhesive and water barrier |
| Window Install | Install window unit | Set window into prepared opening |
| Finishing | Insulate around window unit (post-flashing) | Enhance seal and energy efficiency |
For more detailed information on window flashing best practices, you can refer to resources like the article from Zeeland Lumber which outlines these steps.
