Sash windows are constructed from wood and glass and consist of one or more moveable panels, also referred to as sashes. Sash windows are usually found in older buildings and can be difficult to maintain. One of the most common issues with sash windows is the window becoming jammed shut, which is usually caused by deposits of paint or dirt around the edges of the window frames.
Examine the vertical runs where the window connects with the frame runners on either side of the window. Check if there is any excess paint along these margins as this can cause a sash window to become stuck.
Position a utility knife at the edge of the frame if it appears excess paint or dirt is causing the problem. Run the knife up and down the line of the frame until the paint dislodges from the window frame.
Place a flexible steel scraper in the edge of the window frame if a utility knife does not cure the problem. Lightly tap the base of the scraper with a hammer once it is securely positioned in the gap. Move the steel scraper up the window and repeat the hammer tapping process until you have covered the entire height of the window frame.
Rest the point of a chisel at the base of the window frame around the middle section if the steel scraper is ineffective. Strike the base of the chisel with a hammer so it is forced into the gap in the frame. Avoid using excessive force or you may damage the wood. Using a wide a chisel as possible will also help prevent damage to the wood.
Rub sandpaper along inside of the window frame once you have opened it. Deeply ingrained deposits can be removed with a chisel and hammer. Ensure the window frame is free of all debris before shutting the window to prevent it becoming stuck again.
Use the chisel from the outside of the window when loosening the base and from the inside when loosening the top portion of the window. This will help prevent structural damage to the window and the frame.
Apply candle wax to the runners before shutting the window again. This can help the window open and shut smoothly and prevent future occurrences of jamming.