Nothing is worse than a stuck window on a hot summer day. Unsticking a window requires just a little muscle and the right technique. Windows stick for a variety of reasons. It could be because paint got between the sash and the frame or the channels might just need to be cleaned and lubricated. Because there are more than one reason a window can get stuck, there is also more than one method to get the window moving again.
The following three methods work in most cases. However, if none of these methods works, you'll need to take the window apart to remove excessive paint build up, sand rough edges, and lubricate them with soap or candle wax.
Unstick a stuck window: Method 1
Break the seal all around the window sashes.
Wrap a cloth around a block of wood, place it against the window frame at the bottom of one side, and tap it gently with a hammer.
Be careful not to break the glass.
Go to the bottom of the other side of the window frame and do the same.
Go back and forth between both sides of the sash, moving up, until you’ve reached the top of the window frame.
Unstick a stuck window: Method 2
If the seal around the window doesn't give after you’ve tried Method 1, try using a hammer and a stiff-bladed putty knife to give you a bit more force.
Slide the putty knife into the cracks and tap the handle gently with a hammer.
Work your way around the window sash, tapping gently as you go.
Place a block of wood on the window sill. (On either the inside or outside sill.)
Put a pry bar under one end of the sash and rock the bar backward, over the block of wood.
Go back and put the bar under the sash on the first side.
Repeat these steps, working the pry bar toward the center, until you’ve lifted the entire bottom sash.
Try lifting the window.
Unstick a stuck window: Method 3
The third method is a bit more drastic and involves a utility knife: Try cutting the seal. It’s a slow, tedious process, so be patient and work slowly and carefully. Remember that paint can build up in a number of places.
Run your utility knife in the crack to break the paint seal.
Rattle the sash gently to free it from the window frame.
Try raising the window.