If wooden frames are not maintained, they will begin to rot. Thankfully, it is possible to repair window frames and sills. However, if more than 15% of the frame is rotten, it’s more suitable to replace it.  Our exterior painters take the following steps when restoring window frames: Assessing the rotten wood Removing the rotten wood Apply filler to the gaps Sand the frame and sills Repaint the window frame and sills