How to Install a Window (Step-by-Step Guide)

Are you ready to replace those old, worn-out windows with your new energy-efficient products? The team of experts at Arch…
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Jacob Wadding

Are you ready to replace those old, worn-out windows with your new energy-efficient products? The team of experts at Arch Exteriors has crafted a step-by-step guide to help you find the easiest ways to take out the old window frame and install replacement windows without having to pay a hefty fee.

The Step-By-Step Guide to Replacing Double-Hung Windows

Gather your essential supplies, and follow along as we provide clear instructions on how to install a window from start to finish.

Step 1: Tools and Materials Needed

There are several different tools you will need to effectively tackle this project. Take a look at the list provided below:

  • Utility knife
  • Tape measure
  • Caulk gun
  • Hammer
  • Cordless drill
  • Level
  • Pliers
  • Putty knife
  • Protractor

You will also need to ensure you have the following materials prior to starting the project:

  • Shims
  • Caulk
  • Fiberglass insulation
  • Minimal expanding foam

Once you have all your necessary items at hand, you’ll need to analyze your working area to make the right choice on which replacement methods to use.

how to install windows measuring your window with tape

Step 2: Thoroughly Analyze & Learn Your Window Parts

Use this helpful image to learn the different parts of the window. Refer to this throughout the process if you are ever unsure of which space is being described.

Next, make sure to measure your window opening and existing window frame very carefully to get accurate measurements. The last thing you want is to purchase the wrong size window.

Step 3: Choose Between a Replacement Insert or Sash Replacement Kit

There are two different inserts to choose from, the replacement window insert and the sash replacement kit. See the differences below:

Using a Replacement Window Insert

If you want a new window that’s maintenance-free, it’s a good idea to consider vinyl replacement window inserts. They tilt into the existing frame and are pre-hung. You may even be able to get a simulated wood grain look.

The only issue with replacement windows is that the quality differs dramatically since there are so many available. Thoroughly inspect all the details of an actual working model of the window before you order, including the weatherstripping, locking system, and sash and frame joints.

Using Sash Replacement Kits

If you plan to keep an authentic wood look, you’ll want to use sash replacement kits. The kits include two new wood window sashes, installation hardware, and two vinyl jamb liners to fit within the existing window. Grilles come in your kit and can be matched or painted to fit the rest of your windows. Choose from snap-ins or the glued to glass option.

In order to work, your window jamb must be square and rot-free. Before using, you’ll need to start by measuring diagonally. If the measurements differ more than a 1/2 inch, your new sash won’t seal properly. This is a sign to use vinyl replacement windows instead.

Caution: Houses built before 1978 may have lead paint. Therefore, it’s best to get a lab analysis before disturbing any surface surrounding the window frame. If you’re not sure what to do, contact your public health department for information on do-it-yourself lead testing kits and where to purchase them.

Step 4: Gently Remove Interior Stops

To start your window replacement, remove the interior stops and sash. Use the stiff putty knife against the small pry bar to protect the wood. Make sure to score the joint between the window frame and stop with your utility knife before prying off the window stop. This will help to reduce paint chipping. Then, pull the nails through the backside of the stop with a pliers.

Since the parting stop may be hard to remove, use the pliers to break the lower section, or you can use a chisel to release the upper section as well. If the windows have metal jamb liners or spring balances instead of sash weights, you’ll need to start by removing the interior stops. Then remove all the nails and screws out of the way.

Step 5: Test to See If It Fits

Test the insert replacement window to see if it fits. Don’t worry about it dinging the jamb or window sill. Add insulation if you have a sash weight window. After testing it, remove the insert and use polyurethane window caulk along the inside of the blind stop and on the backside of the window stool.

how to install windows professional installer

Step 6: Put the Window in Place

Rest the window on the sill and tilt it into place against the blind stop. Notice if your window has a head expander because you will need to position it over the top of the jamb first. Tightly press the window against the caulk to seal it.

Step 7: Secure the Window

Since your vinyl or wood replacement insert will be smaller than the window jamb opening, you’ll want to focus on making the frame perfectly square with the sides straight. This will ensure it seals properly and operates smoothly. Then loosely fasten the window into the frame with loose screws in the lower left and upper right corners. By keeping the screws loose, you can readjust the window if need be.

Step 8: Check That It’s Square

After closing and locking the sash, take diagonal measurements on both sides of the new window. Then slide the shims behind the screw holes found in each corner. Adjust these until the diagonal measurements are equal. Once they’re even, add the remaining screws to the upper left and lower right screw holes.

Step 9: Plumb the Window

Open and close the sashes to test to see if the bottoms and tops are parallel with the sill and jamb. Also, look to see if the top and bottom sashes are parallel where they meet. Use a level on the side jambs and slide the wood shims behind the screw hold until the side jambs of the window are straight.

Secure the screws in place and check to see if the sashes slide easily and align perfectly. Be sure to not overtighten the screws so that they don’t warp the vinyl. Then cut the shims with a sharp utility knife.

Step 10: Reinstall the Window Trim and Insulate

Replace the trim and nail it in place with finish nails. Then, measure the size of the gap under the vinyl window sill and cut the vinyl filler strip to fit. You will want to stuff fiberglass insulation in the gap under the filler strip. Next, use the utility knife and straightedge to cut the vinyl. Finally, press it into place.

how to install windows using a caulk gun to seal windows

Step 11: Caulk

Caulk the joint between the blind stop, the window, the windowsill, and the filler strip. Let sit a moment to stiffen.

Step 12: Installing Double-Hung Sash Kits

The hardest part will be tearing out the old window since you will have to carefully remove the stop. Then nail or screw the new liner clips.

Step 13: Find the Bottom Angle of the Sash

Use a heavy piece of paper in the window stop to determine the edge. Fold the bottom and match the angle of the sill. Next, lay your protractor on the folded paper to determine the angle. You will want to measure the interior width and height of the frame to use for ordering the right kit.

Step 14: Remove the Lower Sash

Cut the sash cords to remove the lower sash. Make sure to also remove any hardware or weatherstripping to help remove the sash.

Step 15: Remove the Parting Stop

Pry the parting stop from the groove in the window frame and throw it away. Next, remove the top sash, carefully cut the cords, and remove any sash weight pulleys. Then, stuff the area with fiberglass insulation.

Step 16: Attach Jamb Liner Clips

Screw the new liners in place with No. 6 x 3/4 inch pan head screws. Position the initial clips 4 inches from the top and bottom and then evenly distribute the remaining clips between the two, leaving a 1/16 inch space between clips and the blind stop. This will allow the jamb liner to slide in easily.

Step 17: Place Jamb Liners

Make sure to follow any window instructions as you connect the jamb liners over the metal clips. Align the liner so that it fits nicely. If it has a flap, lay it over the blind stop. Finally, press firmly until you hear or feel it snap into place.

Step 18: Add the Parting Stop

Move the parting stop into the groove in the top, making sure the weather-stripped edge is facing outside. Drill 1/16-inch holes and securely nail the stop in place with finish nails. Repeat this until the interior wood stops.

Step 19: Position the Sash Lifts

Slide sash lifts down the windowsill, leaving around 10 inches. Press down firmly with the screwdriver. Then twist and maneuver it to ensure it fits the new locations.

Step 20: Install the Sash

Hold the top sash with the exterior side facing up, metal cams facing away from you. Gently tilt the sash and carefully align the metal pivots with the jamb liner, making sure the pivots are above the sash lifts.

Next, tilt up the sash and press outward on the jamb liner while also snapping the top part of the sash into place between the liners. Slowly slide the sash down until you see the metal cams connect with the sash lifts. Repeat this for the lower sash as well.

If you have any questions along the way, make sure to reach out to the window experts at Arch Exteriors. Our team is ready to help!

About the Author
Your home is probably the most expensive thing you own. When you hire somebody to make improvements, you want high-quality work. In addition, you hope they’ll take the same care you would. You want someone with a good reputation, legitimate credentials, well established, using quality materials, and who charges a fair price. For over 11 years, I have worked hard to provide all of those benefits to my clients. One of the major reasons we have been able to do that is our ability to keep highly qualified personnel. Our workers are well trained, properly motivated, and managed professionally. I make certain that I convey measurable systems and procedures that our team understands and can readily follow.

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