I Have a Rain Leak Around My Replacement Window

Damage Risks

• Water leaking into your house, whether it's through the window or any other source, can severely damage your home. Even if the water leak is small, over time the accumulation of water can ruin the drywall near the window, soak the flooring and warp the wall studs. The water can also help promote mold growth behind the wall and in the house’s subfloor, weakening the house’s structure and creating a potential health hazard.

Water Resistance

• A replacement window may appear to be keeping rain from entering the house, only to leak water during a different rainstorm. Rainstorms that involve water falling straight down provide a curtain of water hitting the window from above. If a rainstorm involves high winds, the rain suddenly can come at the window from the side. This different angle can lead to rain water penetration when the window normally would stay dry.

Installation Preparation

• Since a window cutout is a hole in the side of your house, you need to properly prepare for the installation of the window to prevent water leaks. Even though the old window may not have leaked, failure to perform the necessary preparation work can leave gaps for the water to flow through. If the house has siding, house wrap must be applied immediately around the window cutouts and under the siding so water that makes its way through the siding cannot leak through the window. Flashing must also be installed around a replacement window to provide another barrier against future water leaks.

Caulk

• Before you install your replacement window, apply a thick layer or caulk around the entire perimeter of the window cutout. The new window likely will not fit 100 percent perfectly within the cutout, leaving some gaps around the window frame and the wall. The caulk closes such gaps. Since the window is sitting on the exterior of the house and is exposed to rain, use silicone caulk for a watertight seal. If after finishing the window installation you find gaps between the window frame and the wall, apply more silicone caulk until the gaps are completely sealed.