How to Install Replacement Windows

Installing replacement windows in your home isn’t an over-complicated task to accomplish but it should be given a reasonable amount of time and will require some skill to complete to a reasonable standard. Once you’ve read a little about what’s involved in a full home replacement you should be good to go. Many families will pay several thousand dollars for the installing of their windows; however you will usually be able to do it yourself for as little as around $300 in total, of course this will vary depending on the type and size of the window you’re going to be installing. Bay and bow window configurations are more expensive to install than most others as you would expect, this is mainly due to their size.

There are 4 main steps in the window replacement process and they are:

  • Gathering your tools and materials together
  • Measuring correctly for the replacement window
  • Removing the old windows from the window frame
  • Installing the new window units into the frame


Cross Section of Window

Usually it will take you around 4 hours to replace a large window in full and of course you are going to need several tools to enable you to do the job. Most people have these tools lying around the home and including things like a hammer, screwdriver, chisel, knife, tape measure, square, wood shims, wood putty, caulking tubes, sandpaper, expanding foam and a pry bar. Once you have all of your tools gathered together you will be able to move onto measuring for the installation.



Measuring Up

Measure twice, cut once

It doesn’t matter what type of window you are using the measuring essentials are basically the same from unit to unit. It’s important that this is done right because everything else you do will stem from this.

When you’re undertaking the measuring process you will need to obtain 6 measurements in total, 3 along the horizontal aspect and 3 along the vertical aspect. The height and the width measurements are taken from the window jamb to the window jamb, this basically refers to the inside edge of the window frame. It’s important that along both axis that 3 measurements are taken, one to the left, middle and right when measuring the height and one to the top, middle and bottom when taking measurements for the height. You may see that these measurements are not all the same, if this is the case then you will need to take the smallest height and the smallest width measurement, these will be the dimensions for your new window.


The first thing to be removed will be the window stops, these are the things which hold the window in place within the frame. On older windows it may just be a case of unscrewing them or using a utility knife to cut the edges away and pull them out. You should try not to damage the window stops if possible as these can be reused and save you a little bit of extra money.

The next step should be fairly straightforward now that the window stops have been removed, you will need to remove the window sashes or the window panel, depending on the type of window which is currently installed. Because the stops hold the window in place the sash or pane should just lift out with very little effort.

Finally, you should take out any parting beads to allow you to remove the final part of the window sash, if it’s a casement window you’re removing you will often not have a parting bead in the installation. Now that your window is out you will be able to fill any holes in your window jambs, smooth them out and get them ready for the new windows.


Final touches of installation

The final part of the process is the hardest, installing the new replacement window. The first part of the process will be to lay a bead of caulk along the inside of the outside stops, this is where the replacement windows are finally going to rest against. You can then go ahead and install the first part of the window which will be the window header, this should be installed into the top window jamb.

Next, you will insert the replacement window unit into the square hole and see if it fits into place. If the window doesn’t quite fit because it’s too small then you will need to tap some wood shims into place to make it a tight fit in the window hole. Once the window is fixed well in place you will be able to screw the window onto the jamb so it’s fixed in place.

You can now go ahead and check to see if your replacement window works okay, try opening and closing the main parts of the unit and making sure parts which aren’t meant to move don’t move.