Casement windows come with their share of problems. When one of these types of windows becomes stuck, in many cases it can be difficult to break free. Any homeowner can free a stuck casement window.
Look to the most common cause of a stuck casement window first. A layer of paint that has sealed the window shut is often the problem.
From the outside, slide a knife or similar thin, sharp-edged tool along the edges of the window between the window frame and the outer frame, breaking through the paint layer. Run the blade up and down the length of the frame, on top and on bottom to break through the seal.
Use the same tool to gently pry the window away from the outer frame a little at a time, starting at the top and working down to the bottom. Have a helper try cranking open the window while you do this.
Inspect the cranking mechanism for both stripped teeth beneath the handle and to see if the gears inside have become locked. Either situation warrants swapping out the cranking mechanism with a new one.
Check the window lock for signs of also being painted shut in the closed position. Use a scraper to scrape off the paint, and get to any hard-to-reach areas with a flathead screwdriver. Spray the locking mechanism with WD-40 or another lubricant and jiggle the lock handle back and forth to get it open.
A heat gun can help soften up heavily painted areas of the window so that you can more easily remove it.