I bought a property in August 2018. A month ago, so far twice during heavy rain and wind, the water started to leak above the kitchen window. There is a small gap between the window and the wall and water is coming through there. At first, I thought that I needed to replace the windows and fill the small gaps with a sealant so I called a designer to give me a quote. After he inspected the kitchen and the window from inside and outside he told me that there is nothing wrong with the window itself, but that water is coming from the outside wall somewhere from above. The roof is inspected and there are no leaks in the property above mine. As can be seen on the kitchen ceiling, there is no damp or leak. There were also no damps or leaks previously in the kitchen. The previous owner has done some work on the outside above the kitchen window. I am wondering whatever has been done back then could be botched work and what could be an issue? Lintel, cavity tray? I have no idea how to approach a problem. Should I call a local bricklayer or construction company? What they should repair? Lintel, cavity tray, or should they re-roughcast externally to weatherproof the exterior walls? Overall, the apartment is in very good condition, with no leaks on other windows and no sign of damp.
IMPORTANT EDIT TO THIS QUESTION:
The window from the outside is not sealed all the way around. Could this be the initial problem? Should I call the handyman to seal properly the window from outside and see if this will solve the issue? Or should I just call the handyman to fix the cavity tray and seal the window from outside?