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Window Sills

Window Sills by SFI, Inc.

At SFI, Inc. we can supply you with window sills that fit your needs.
Our sills can be made and ordered at almost any depth. The
standard depths are 4″, 6″, 8″, and 10″. The maximum length of a 1-
piece sill is 10” or 120″. Window sill molds are 3/4″ thick, and
finished products are 5/8″ to 3/4″ thick.

Sill pricing is per square foot (rounded to the next 1/2 square foot).
To calculate square footage: length of piece x depth of piece,
divided by 144 and round to the next 1/2 square foot.

  • Example: 59″ x 6 = 354. Divide by 144 = 2.458, round to 2.5
    square feet.
  • Example: 64 x 7 1/2″ = 480. Divide by 144 = 3.333, round to 3.5
    square feet.
  • Sills deeper than 10″ are a higher price per square foot.

Ordering Options

Cut to Length

  • Sills are run in lengths up to 10” and cut to size on the order.
  • Length should be true to specification on order.
  • The final product will have the front edge finished, but the ends will be cut. The exposed portion of the ends (the inch or 3/4″ that sticks out past the wall after installation) will be raw/cut. The color of the back pour will show, but the end will not be gel-coated.

Made to Length

Each sill is made individually, and to accommodate shrink, is set up slightly longer than the length specified. The amount a sill shrinks can vary. Factors that affect shrink are the following:

  • Air temperature
  • Humidity
  • Resin batch, resin temperature
  • Catalyst percentage
  • Temperature of mold
  • Size of batch being poured

Because of the shrink, length of sills cannot be guaranteed to exact
measurements of the order. The finished product will have the front edge and the front 2″ of each end finished. This option is more labor intensive.

Colors and Finishes

Window sills are available in all SFI colors, and sills can have either a matte or gloss finish.


SFI, Inc. expressly warrants each of its manufactured window sill products for a period of either five (5) years or one (1) year. The warranty length depends on which color is chosen for the window sill: