After reading a window replacement estimate, and once you've caught your breath again, you may be considering a do-it-yourself replacement window project. Replacing windows yourself is not unlike what a professional window company would do, but with a few less extras. Before considering your own window replacement project, keep in mind that replacement windows can vary in their installation instructions, so it's important to pay close attention to those instructions when replacing your windows.

You will need a few things before getting started. Having the right tools for a job is always wise - both for your sanity and for the success of the project. The following are window replacement tools and materials needed for the job:

A dripless caulking gun and caulking tubes

A square

Wood shims

Tape measure

Miter saw

Hammer

Cordless drill

Screwdriver

Wood chisel

Utility knife

Small prybar

Replacement window

Remove Old Windows

With tools in hand, take measurements of your window (inside the house) from the inside of the window jamb to the inside of the opposite jamb. Windows can warp and skew over time, so make sure to measure at bottom, middle and top. All measurements should be equal or within one quarter inch. If not, choose the smallest measurement as your guide.

Now take vertical measurements, measuring from the inside of the sill at the top to the inside of the top window jamb at the bottom. Measure at the left, middle and right, taking the smallest measurement. Keeping the smallest measurement ensure that the replacement window will fit in the opening. Gaps can be filled in later.

Working from inside the house, it's time to remove the old window. Using the prybar, screwdriver and utility knife, remove the stops. The stops are the thin, vertical pieces of wood that prevent sashes from falling inward into the house. Be careful not to damage the surrounding materials as you work the window out. A quality utility knife allows you to easily and safely slice any paint that is adhering the stop to the window frame. Once you've created a gap, you can switch from the utility knife to the prybar. Shims are also useful as they protect the surrounding materials when using the prybar or hammer claw. Set the stops aside for later use.

Then, remove the inside sash and cut any sash cords or chains (found on old windows). Let the weights fall into their pockets and cut away any exposed rope and let the rest fall down. Slide the outside sash down and remove and discard the parting beads, which are the vertical strips that keep the sashes on track. Remove the outside sash but leave the outside stops intact.

Clean up and prepare the inside faces of the window jamb and sill so they are ready to accept the new replacement windows. You will want to sand any splintered wood, patch holes with wood putty, and fill large holes with bits of fiberglass insulation.

Install New Window

Before doing anything else, set the new window in the existing window opening to see how it will fit. Position the window sashes within the new window unit at the center of the window unit. So you can see the four mounting holes on the sides of the window unit, slide the bumper stops toward the center. With your caulking gun, caulk along the inside of the outside stops on the jambs. Mark the sill for the sill angle and caulk and install the sill angle.

Now insert the header or expander on top of the window unit and caulk along the top. Use the provided screws to secure the header. Place the window in the opening, using your square to check all four corners for squareness. If needed, tap in shims where needed to even out the window. Secure the window with the mounting screws on each side of the jamb. Adjust the header until it closes any gaps between replacement window and window frame. Again, use the provided screws to keep the header in place.

Test the smashes for smooth sliding, using the adjustment screws to adjust operation. Caulk inside the window and install the stops that you saved with finish screws.

Enjoy the natural light and insulation your new window provides.