Expert: Dan Griffin - 12/21/2010

Question
Hello,
I bought an old single story house that made out of Concrete block cmu. I started to replaced the old windows with new windows but I don't know how. Can you help guide me step by step, picture? or direct me to any information that will help me with this process. Thanks, Bryan

Answer
Bryan, the big chore is to have a plan as once you remove the old window, you must be prepared to close the opening.

There are several methods depending on the original window design.  I am guessing that the original windows are aluminum framed windows or steel casements.  These are probably trapped in a groove in the blocks.  It is often easiest to saw the original into smaller pieces to remove the pieces = this method usually reequires removing the glass.  If the windows are aluminum, it is possible to cut the flange off the window.  The first window will take some experimenting to find the best or easiest method.  Start on a small window that is easy to get to both inside and out.

New widows should be ordered and on site before you begin so you are ready to proceed.  Replacement windows should be carefully measured to be slightly smaller than the available opening.  The new windows will be held in with Tapcons or similar in the sides and an application of structural caulk to complete the installation.  Make sure you have a good system in mind to deal with flashing the bottoms to send any water to the block face with a bit of slope.  I would not use silicone or any latex caulk on the exterior.

There is no "one" answer that will work.  The plan, the measuring, the attention to detail make all the difference in the world.  Make sure you have a plan.  Have a sheet of plywood or similar to cover the hole if things go wrong.  Good luck.

Here are some youtube videos.  Try to find your type of window:
http://www.youtube.com/watch?v=cqlkPCrAve4&playnext=1&list=PLC21803D113F512B3&in...