Liquid-Flash a Windowsill Pan
Liquid flashing offers a seamless alternative to flashing tape.
Liquid flashing is becoming a popular method for sealing window rough openings because of its ease of installation. Here’s how to do it.
Any good window flashing job starts with a sloped sill, which ensures that any water that might get in around the window will drain to the outside. Adding a piece of beveled siding on top of the rough sill is a simple way to create the slope.
Then, with a tube of liquid flashing in your caulk gun, start by applying a thick bead to visible gaps, like in corners and where the framing meets the sheathing.
Then move on to the sill. In this video, we applied multiple beads to the sill, but you can also lay down a zig-zag bead. After that, apply liquid flashing at least 2 in. onto the face of the wall sheathing, and up the jambs by at least 6 in.
Next, spread the wet flashing to create an even skin without any holes. A plastic spatula, a stiff brush with the bristles cut short, or a putty knife are all good tools for spreading the product around to an even film.
The recommended coating thickness will vary by manufacturer, but no matter which product you choose, it needs to be applied thick enough so you can’t see the wood or sheathing through the flashing.
If framing or sheathing is visible, apply more liquid flashing to the area, and smooth it out.
Once complete, allow the liquid flashing to cure before installing the window. For products that are moisture-curing, the cure time can be shortened by spritzing the flashing with water. Dry times vary by manufacturer.