Hello guys, I've found a lot of useful info here but this is my first post. I hope I've clearly expressed a complex situation.
My girlfriend has asked me to look at the installation of her sitting room window, which was done before I came on the scene. It's a bit of a mess. The wooden timber frame has been fitted straight into the reveal in a brick-and-block wall. There's no DPC and the frame is too small, leaving a 2cm gap l+r and 1cm at top. The gap has been filled in with a thick layer of render and the gap between timber and render has then been filled in with some kind of silicon sealant. Under the circs it's no surprise that there's a damp problem on one side of the frame. (I'm surprised that it's not happening on both sides!)
I imagine the best way to proceed would be to remove the window frame, build up the sides of the brickwork to reduce the size of the gap, then refit the frame with a proper DPC in place. However, that's a large job, and would require a lot of cleanup inside the house.
I'm inclined to dig out all the surplus render, run a high-quality weatherseal around the window frame, push nylon slats into the gap between frame and brickwork and screw them into place, then render over the nylon. I know it's brutal, but it could be done without disturbing the window.
Let me know if you can suggest a better way...
TIA, NP