How to DIY Removing Old Windows

Using common carpentry tools, you can install a sash kit or window insert from inside your home without destroying the surrounding interior molding or exterior casing.

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Project Overview
  • Working Time: 5 hours
  • Total Time: 5 hours
  • Skill Level: Intermediate

If you have the right tools and tips, installing a window yourself can be a weekend project. Whether replacing a damaged window or just wanting a new look, we'll show you how to get the desired results without needing help from a professional. Check out our steps below and get started today.

Removing old windows and installing new ones as a DIY project will only work when the new one is the same size and shape as the old one and the existing one is square. To determine if your window opening is square, measure diagonally one way (from the upper left corner to the lower right corner) and then the other (from the upper right corner to the lower left corner). If the opening is square, the two measurements will be the same, give or take 1/8 inch. The slightest deviation from square can prevent the sash from closing and the weather stripping from sealing properly. You'll be stuck with drafts, condensation, and high utility bills if that happens.

What You'll Need

Equipment / Tools

  • 1 Utility knife
  • 1 Pry bar
  • 1 Pliers
  • 1 Hammer
  • 1 Level
  • 1 Caulking gun
  • 1 Paintbrush
  • 1 Drill and drill bit
  • 1 Slip-joint pliers
  • 1 Reciprocating saw
  • 1 Handsaw

Materials

  • 1 Sash replacement window
  • 1 Nails
  • 1 Caulk
  • 1 Wood putty or filler
  • 1 Paint

Instructions

  1. Measure Window

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    Successful replacements depend on good measurements of the existing opening to determine the size of your new window. Start by measuring between the left and right jambs at the top, middle, and bottom; the shortest of these three measurements is the window width. After that, measure the distance between the head jamb and sill at the far left, middle, and far right side; the shortest of these three measurements is the window height.

  2. Removing Old Window Trim and Head Stop

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    Score the paint where each piece of trim meets the existing window casing. Scoring the seams prevents the wood from splitting when you remove the trim pieces. Slide a flat pry bar behind the inside stops and remove the pieces.

    Next, score head stop and gently pull it loose with pliers. Set aside for later use.

    If you wish to remove the surrounding trim, use a utility knife to slice through any paint or caulk between the interior casing and the wall. Use a flat pry bar and a scrap piece of wood to remove the casing. If you'll reuse the casing, use slip-joint pliers to remove the screws.

    Tip: After removing a stop or other trim pieces, use pliers to pull the nails through the back of the piece. Doing so reduces the odds that it will split or fracture.

  3. Remove Jamb Liner

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    Raise the lower sash 6 to 8 inches, then pry back the old jamb liner. Repeat with the upper sash.

    Fold the jamb liner at a 90-degree angle underneath the sash. Repeat with the upper sash, folding the jamb liner across the top of the sash.

  4. Remove Window

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    Remove the old sashes and jamb liner as a single unit. You may need a helper for assistance with larger windows. With a helper standing outside to catch the window, start prying outward. You may need to tap the jambs with a hammer. Once the window is loose and ready to fall, go outside to help with removing the old window. Use proper lifting techniques to avoid back injuries.

  5. Insert New Jamb Liner

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    Install a liner bracket every 4 to 5 inches along each jamb. Make sure each bracket is level before you nail it on.

    Attach the jamb liners to the liner brackets. Each liner should pop into place.

  6. Install Sashes

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    Insert the upper sash in the exterior track of the jamb liner. Open and close the sash to make sure it slides smoothly. Insert the lower sash in the interior track and check that it operates.

  7. Install Head and Side Stops

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    Reattach the head stop. Set the nails below the wood surface. Fill the holes with wood putty and touch up with paint.

    Reattach the inside stops. Set the nails and fill the holes with wood putty. Caulk the seams and touch up with paint.

  8. Remove Casing

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    Use a utility knife to slice through any paint or caulk between the interior casing and the wall. Use a flat pry bar and a scrap piece of wood to remove the casing. If you'll reuse the casing, use slip-joint pliers to remove the screws.

  9. Remove Sash Weights

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    If you have an older wood window with sash weights, pull back the cords or chains and cut the ones that attach to the weights for the lower sash. Pull down the upper sash and do the same. Remove the sash weights.

  10. Remove Molding

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    On the exterior cut through any caulk and pry out the molding all around the window.

  11. Remove Stool and Apron

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    Inside the house, pry out the stool (inside sill). It may be easiest to cut through the nails first (see next step). Also, remove the apron, which is attached to the wall directly below the stool.

  12. Cut Through Nails

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    Cut through the nails that attach the jamb to the house's framing. A reciprocating saw works best for this, but you can also use a hacksaw. Or slip the notch of a flat pry bar onto the nail's shank and bang hard with a hammer to break the nail.

  13. Remove Insulation and Sashes

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    Pull out any insulation and other obstructions, and check that all the nails have been removed. Remove one or both sashes.

  14. Pull Out the Window

    With a helper standing outside to catch the window, start prying outward. You may need to tap the jambs with a hammer. Once the window is loose and ready to fall, go outside to help pull it out.

    Removing Old Windows from the Exterior

    A metal or vinyl window may have a flange nailed to the sheathing and covered with siding; in that case, you must cut back the siding. Molding that rests on top of the siding is the easiest to remove.

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