Replacing windows in block house

My best advice about measuring windows, is to let a rep of the place that is selling you the replacement windows do all of the measuring or YOU will be liable for any errors.
Or carefully use the illustrated directions on how to install them.

Just ”tack” your old casings up temporarily. Chances are that you will have curtains covering them anyways.
Take your accurate measurements for height and width. Double check your measurements. Re-install your casings. Do this for any other windows that you have.
These are your ROUGH OPENING measurements for “New Construction” style windows (frames and all). Use these measurements to start consultation for window ordering. (BTW-Be aware that installing New Construction style windows requires extensive work on the exterior areas for the nailing fins/flanges).
Are you installing vinyl windows? Are there windows in place? Aluminum or otherwise? If you are retrofitting vinyl windows into existing windows, you take out the glass and center metal leaving the frame intact. Then you measure the opening that you can slip in a flush fin retrofit vinyl window. Then deduct about 3/8 for clearance (about 3/16 on each side) you order the windows to that size. Make sure you get flush fin. Tell the supplier what you are doing. You can get some trim strips also. Then screw the window in place, insert some insulation around the perimeter and maybe some latex caulking and install the trim strips.

Apart from this, installing windows in block houses wouldn’t bother you much!

Written with creative assistance from: http://creativecp.org/