The short answer
A draughty window is almost always a compression problem — the sash no longer presses evenly onto its gasket. Condensation is a separate issue, and where the water forms tells you whether you have a ventilation problem, a failed sealed unit or a cold-bridge at the reveal.
Draughts: what has actually failed
A uPVC or timber casement seals by squashing a rubber gasket between the sash and the frame. That relies on the sash being square, the hinges holding it in the right place, and the locking cams pulling it tight. Any one of those going out and the compression is lost on one edge.
You can usually feel the pattern: a draught along one edge only points at hinge or cam adjustment; a draught all round points at a perished gasket; a draught from the reveal rather than the window itself points at the gap between frame and wall.
Condensation: read where the water is
Water on the room side of the glass is condensation from the air inside the house. It means humidity is high and the glass surface is cold — a ventilation and heating issue, not a broken window.
Water trapped between the panes, or a permanent haze you cannot wipe off, means the sealed unit has failed and lost its gas fill. That unit needs replacing; nothing else will clear it.
Water on the outside face of the glass on a clear morning is not a fault at all — it is a sign the glazing is insulating well and the outer pane is staying cold.
Condensation and mould concentrated at the reveals and corners around a window points at a cold bridge in the surrounding construction.
Why sealing everything up is the wrong instinct
The common reaction to a draught is to block every gap in the room. Trickle vents get taped over, extractor fans get turned off because they are noisy, and internal doors get draught-stripped. The draught improves and the condensation gets dramatically worse, because the moisture the household produces every day now has nowhere to go. Black mould at the reveals and on the ceiling corners usually follows within a season.
Expanding foam around a frame is the other one to be wary of — it can bow a frame as it cures and make the sash impossible to close properly.
Working out which of the four condensation patterns you have, and whether a draught is a hinge, a cam, a gasket or a perimeter seal, decides whether the answer is an adjustment, a new gasket, a new unit or ventilation. They are not interchangeable.
How we put it right
Window and door adjustment, from £45
Hinges, cams, gaskets and perimeter seals checked together, with an honest answer on whether a unit needs replacing.
Serving Leamington Spa, Warwick, Kenilworth, Whitnash, Cubbington, Southam and surrounding Warwickshire.
Common questions
Can misted double glazing be fixed without replacing the glass?
Not reliably. Once the perimeter seal has failed, the unit has lost its inert gas fill and its insulating performance along with it. Replacing the sealed unit is the durable answer; the frame usually stays.
Why is condensation worse in some rooms than others?
Bedrooms and bathrooms generate the most moisture and are often the coolest overnight, so the glass there hits dew point first. North-facing rooms and those on external corners are typically worst.
Do you adjust windows as well as doors?
Yes — hinge, cam and gasket adjustment on casement windows is the same family of work as our door alignment, and we usually pick up several in one visit.