Window Flashing Tape
Leaks happen!! The best method to ensure that water leaks do not get in and under windows is to use window flashing tape. When combined with a sloped sill, a self-adhered, rubberized window flashing tape can create a continuious water barrier.
One of the better flashing materials is DuPonts FelxWrap. As a carpenter I like this flashing because it efficiently conforms around custom shapes, bridging the interface between the rough opening and the building envelope.
How It Works:
The DuPont FlexWrap window flashing tape is an expendable flashing material made with 100% a butyl-based adhesive layer. It allows you to flash a window or door opening with one seamless piece of material. no seams – no leaks. The product is also very effective for flashing round top windows or custom shape areas.
Read more on Flashing Issues