How to Install a Bay Window

Get the reading nook you've always wanted with a picture-perfect bay window. After a bit of labor, you'll love the results!

Mini Farmhouse Makeovers
Project Overview
  • Total Time: 2 days
  • Skill Level: Advanced

What is a home without a picturesque window to gaze out of? Whether it's used as a reading nook, a breakfast seat, or a picture display, a bay window looks lovely in any home. Make this dreamy feature yours this season by installing one yourself! Homeowners with previous handiwork experience can feel confident following the steps provided below. Beginners may want to enlist help from friends or professionals with basic construction knowledge. This task should take one to two days, so it's the perfect weekend project!

What You'll Need

Equipment / Tools

  • Measuring tape
  • Drill
  • Hammer
  • Level
  • Stapler
  • Caulking gun
  • Screwdriver
  • Flat pry bar
  • Circular saw


  • Bay window
  • Exterior casing
  • 2x4s
  • Shims
  • Caulk
  • Roofing felt or building paper
  • Drip cap
  • Flashing
  • Plywood
  • Roofing
  • Finishing nails
  • Staples
  • Roofing nails
  • Interior trim
  • Casing nails
  • Insulation


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    Frame and Support Cables

    Before you begin, read the window's instructions carefully and be sure to install the required cable support. In one arrangement the cables are attached to an overhanging eaves structure. Cable attached to a header or studs must be at an angle no flatter than 30 degrees. Whichever method you choose, plan how you will cover the cables with a roof or a short wall up to the eaves. Some units have cables preinstalled; with others, you have to add the hardware for the cable yourself.

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    Prep the Opening

    Your opening should already be cut and framed. Flash the opening. The jambs of the window shown fasten directly to framing members. Some other bay windows have flanges; with such units you'll need to set the window in temporarily, shim it square, mark for cutting the siding to accommodate the casing, and cut the siding.

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    Mark Fasteners and Drill

    Following the manufacturer's instructions, mark the fastener locations. Drill four or so holes in the unit to allow you to firmly fasten it in place for shimming and leveling.

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    Temporarily Fit Window

    Cut a pair of temporary supports. With a helper or two, raise the window into place and temporarily support it. Check for level and plumb all around and shim as needed. Drive screws at the top and sides to temporarily hold the window in place. Check that operable windows open smoothly.

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    Construct Roof

    Make a template or carefully measure so you can prefab the roof. It is much easier to fine-tune the angled cuts and install the pieces while working at ground level. Drill large holes for the support cables. Measure and cut the final sheathing pieces.

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    Install Roof

    Set the roof in place and mark where you'll cut the siding to allow for the flashing. Use a spacer to mark for adequate flashing space. If needed mark the siding for cutting, remove the window, and cut the siding.

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