How to Install Arch Windows

Lead Image for How to Install Arch Windows
  • 2-4 hours
  • Intermediate
  • 700-1,900
What You'll Need
Tape measure
Pry bar
Utility knife
Expanding foam
Caulk gun

Putting arch windows in a house can add an element of beauty that you cannot get with any other type of window. The job of putting arched windows in the house can be difficult, and many people like to hire an installer to do it for them. However, you can do this job yourself if you take your time and make sure that you do it correctly. Here are the basics of how to install arch windows effectively.


Before you can install a new window, you need to make sure that you measure it appropriately. You need to use your tape measure to get the exact dimensions of the window. Get the radius of the arch and the width across as well. Be very exact with this process and make sure that all of the measurements are correct.

Remove Old Window

If you have existing windows in the frame, you need to start by removing them. If you are putting new windows into an empty frame, you don't need to worry about this step. Start out by taking a pry bar and prying off the frames around the window. You should then be able to use a hammer to take out the window stops.

Insulate With Foam

Once you get the window out, you may need to fill in around the edges with expanding foam. This process will give you some added insulation around the outside of the new window and it will give it some extra support as well. Allow the insulation to harden before proceeding.

Caulk the Stops

You should then apply a bead around the inside edge of the blind stops. Take your caulk gun and use elastomeric caulk for this job.

Place the Window

At this point, you are ready to put the window into place. You should most likely get some help from someone else, to make sure that you get it up into the window frame without any issues. You should be working from the inside of the house when putting up the window. Set it into the window sill and then press the top up towards the frame.


You will then need to apply shims around the outside of the window. Adjust the shims to center the window and make sure that it is straight level, and plumb.

Screw It

With the window properly adjusted, drive a screw through the side of the window frame at the top, so that it will hold the window up in place. The screw should go through the window and shim and into the frame.

Finishing Up

Once it is in the proper place, you can finish screwing it in through the pre-made holes in the edge of the window. The screws should go into the window frame. If you have any shims hanging out, cut them off with a utility knife. You will then need to fill any gaps with expanding foam or caulk.