How to Replace a Window

Open Windows

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After an unusually high estimate for replacing windows, some homeowners may consider a do-it-yourself window replacement. The process of replacing your own windows is largely the same as professional window companies do, but with fewer bells and whistles and a lot more uncertainty. At the same time, hiring a professional company to replace your windows adds more cost to the project. But the job goes faster and you likely can expect better results.

New-Construction vs. Replacement Windows

New-Construction Windows

New-construction windows have nailing fins attached to the window perimeter that allow the window to be nailed flat against the outside of the house.

New-construction windows are meant for new homes or for extensive remodels that involve radical exterior changes.

The windows that are readily available on the shelves of home centers and builder's supply houses are usually new-construction windows.

Replacement Windows

Replacement windows are sometimes called pocket windows or insert windows. This window has no nailing fins and is meant to fit into an existing frame.

Replacement windows are meant for retrofits only. Using replacement windows minimizes the construction since the window frame does not need to be rebuilt.

DIY Window Replacement

Replacing windows is a generally safe project made even safer with the help of a competent work partner. Sash weights from old windows often contain lead, so they need to be handled safely and disposed of properly.


Replacing windows is not a project for beginners. Our experts strongly recommend hiring a professional to make sure the project is completed properly and safely. If you are a competent home improvement veteran, you may be able to complete this project, but work carefully.

While professional builders and window companies have ready access to replacement window supply chains, the windows can be more difficult for do-it-yourselfers to find and purchase. If only because of this difficulty, most homeowners opt to have professionals install their replacement windows. Additionally, it can be a challenge to precisely measure window frames for the new windows.

  • Saves on labor costs

  • Replace windows on piecemeal basis

  • Windows not easy to obtain

  • Sizing is difficult

  • Tough to install weathertight windows

Overview of Replacing Your Own Windows

Because there is a significant learning curve, you may spend several hours on the first window or two. After that, each window may take about an hour or so. You'll need dry, warm weather, and it always helps to start early in the day. This is just an overview—if you are replacing your windows yourself, do thorough research and follow manufacturer or installation instructions to the letter.

Basic tools are required, such as a circular saw, cordless drill, level, hammer, caulking gun, and a tape measure, plus a few others. Materials are limited to the replacement window itself, nails, shims, caulk, and some window trim.

  1. Measure the Window Space: Measure from the inside of one window jamb to the inside of the opposite jamb at the bottom, middle, and top. Choose the smallest measurement. Keep the smallest measurements so that the replacement window you order will fit in the opening. Gaps will be filled in later.
  2. Remove the Trim and Window Stops: When removing the old window, you avoid damaging surrounding materials. You'll need to delicately remove the stops and trim. Set them aside for possible later use.
  3. Remove Sash Weights, Cords, and Pulleys: Cut sash cords or chains. Remove the sash weights, if possible. Remove the parting beads, those vertical strips that keep the sashes on track. Remove the window sash.
  4. Dry-Fit the Window and Shims: Place the replacement window in the window opening. Gauge how it fits with the shims in place. Shimming is always required. If the gaps are too wide and the shimming too extensive, you may need to order a new window.
  5. Fit the Window in Place: Caulk the sill, then place the window in the opening. Use a square to check all four corners for square. Tap in the shims, leaving about an inch protruding. Screw in the provided mounting screws at the top and bottom of each side jamb. Do not over-tighten the screws. Move the header up until it closes any gaps between the replacement window and the window frame. Use the provided screws to fix the header in place.
  6. Test the Window: Test both sashes for smooth sliding. If the sashes are tight, use the adjustment screws to adjust the operation. If this does not fix the issue, you may need to remove the shims and try thinner shims. If the window now fits, saw off the protruding ends.
  7. Apply Caulk and Trim: Caulk inside of the window. Install window trim around the window.

Replacing Your Own Windows by Hiring Pros

Hiring a window company to replace your windows is usually faster and more efficient than replacing windows by yourself.

Window companies know how to measure window openings to account for minute variations that do-it-yourselfers may miss. Companies, too, are experienced at ordering the right kind of window for each opening. Installation typically is completed within a day or two for most homes. Installers can push the installation season into fall and winter since they are able to quickly remove old windows and replace them.

Labor charges are the main cost to the homeowner. Expect to pay between $150 and $800 per window for labor.

  • Fast installation

  • Precise work

  • Installs in four season

  • Labor costs

  • Time spent researching window companies

Overview of Pros Replacing Your Windows

  1. Estimate: Most homeowners solicit window replacement estimates from multiple companies. A representative looks at your windows and discusses replacement options. An estimate usually takes about 30 minutes and is free. You may receive a quote on the spot or soon after. You may sign the contract at that time. If you want to consider, you may sign later.
  2. Measuring: After choosing a company, you'll receive a second visit. This person will take precise measurements so that the windows can be ordered.
  3. Installation Preparation: On installation day, the crew will lay protection on the floor and below the window opening.
  4. Remove Old Windows: The crew removes the interior trim and cuts out the old windows. In some cases, the glass may break, but usually the process is fairly clean.
  5. Insert New Windows: The new windows are inserted into the current frame. Sometimes, light carpentry may be required to repair the window frame.
  6. Install Exterior Trim: Exterior window cladding or trim is installed to form a weathertight bond.
  7. Cleanup: The crew removes all protective coverings, cleans the windows, leaves your home broom-clean, and cleans up the yard.