DIY Sill Pan
A sill pan is a three-dimensional structure that is placed on a roughed-out window opening before the window is installed. It prevents any moisture arising from window failure from seeping into the walls of the structure. In the past sill pans were metal and constructed off site. Then prefabricated lengths of PVC or plastic pan material were introduced. Now, with modern materials, this process of sealing a window opening can be done on site in minutes. Multidirectional and stretchable window flashing has made rigid sill pans a thing of the past. Quickly build a sill pan with these new window flashing materials. Does this Spark an idea?
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Things You'll Need
- Level
- Compass
- Stretchable window flashing material
- Tape measure
- Framing Square
- Heavy scissors
- Permanent marker
- Heavy cloth gloves
- Utility knife
- Light construction stapler
Instructions
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1
Check the window opening for finish status before you begin the sill installation. It should be fully framed, with a 10- to 15-degree down-and-out slant to the sill. There must be no nail heads or other protruding metal or wood that could penetrate the window flashing material.
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2
Measure and cut a piece of flexible window flashing material that is as long as the sill plus 12 inches. This provides a 6-inch run-up on each side. (This material comes in varying widths; pick one that is 4 inches wider than the opening.) Mark the center of its length with a bold marker.
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3
Wipe the sill thoroughly with a damp rag and allow it to dry for 2 minutes.
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4
Pull off the inside-facing strip of backing on the material. These materials have a split adhesive cover strip on the backside, permitting them to be rough-placed before the other strip is removed. Carefully place the flashing material on the sill, touching the center first and smoothing it onto the sill in a double-outbound movement. Remove the other cover strip. Tuck the material into the corners and up the sides of the frame. At this point the material will be jutting out of the frame at right angles to outside lines of the opening.
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From inside the structure, using both hands, drive the material out, over and around the vertical and horizontal outside edges of the opening corners in a single movement. This is the keystone operation of the installation process, allowing a two-dimensional fabric to be stretched over a three-dimensional corner. Smooth the fabric repeatedly until there are no bubbles or ridges in the material.
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6
Use a utility knife to trim the outside edges of the material to a 2-inch width. Use a light-duty construction stapler to drive ½-inch staples all around the outside surfaces of the opening.
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7
Finish the inside edges of the fit by folding the material back onto itself, flush with the inside edges of the window frame. (Note: there is no inside tacking or stapling of the material. It is sealed by the adhesive and will be anchored when the window is set in the opening.)
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Tips & Warnings
Practice the hand-smoothing operation several times without removing the adhesive cover strip.
References
- "The Definitive Guide to Windows Installer"; Phil Wilson; 2009
Resources
- Photo Credit Brand X Pictures/Brand X Pictures/Getty Images
