I've noticed that there's a gap letting a draught in on one vertical side of my top-hung window. The seals are tight at the top, left side and bottom. The gap is largest at the middle of the right hand side of the window (which meets the central mullion) but closes at the top/bottom - kind of implying to me that either the window frame or the mullion is not straight?
Quite hard to photo, but picture below. LHS is the opening window, arrows point to the gap between the window frame and the seal on the mullion.
Quite hard to photo, but picture below. LHS is the opening window, arrows point to the gap between the window frame and the seal on the mullion.
