an exploded view illustration of windowbox construction
Illustration: Gregory Nemec
Download and print the cut list for building a PVC windowbox.

PVC windowbox cut list
We built a 30-inch-wide window box designed to sit beneath a 32-inch-wide window. For boxes longer than 48 inches, add a third bracket at the center of the box.

1x10 PVC front and back pieces: two @ 30 inches
1x10 PVC end pieces: two @ 7¾ inches
1x10 PVC bottom piece: one @ 30 inches
1-by-1 -inch PVC outside-corner molding. Cut to fit.
PVC cap molding. Cut to fit.
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    Tools List

    • 16-foot tape measure
      Tape measure
    • miter saw
      Sliding compound miter saw or a circular saw
    • hand clamps
    • brad nailer
      Brad nailer
    • drill
    • spade bit
      ½-inch spade bit to make the drainage holes
    • 1/4-inch drill bit
      ¼-inch bit to drill pilot holes into a wood-frame house
    • 3/16 masonry bit
      Masonry bit to drill pilot holes into a stone or brick house
    • four-foot level
      4-foot level to make sure the brackets are level

    Shopping List

    1x10 PVC board for the box frame. Get a 12-foot length.

    1-by-1-inch PVC outside-corner molding for the vertical trim. Get an 8-foot length.

    PVC cap molding for the top and bottom. Get two 8-foot lengths.

    1½-inch brads for securing the box frame

    ¾-inch brads for securing the molding

    -by 3-inch lag screws to secure the brackets to the house

    1¼-inch deck screws to secure the window box to the brackets

    1 pair of weight-bearing window-box support brackets

    Masonry anchors for stone or brick walls

    PVC cement