expanding foam window cavity problem, help please

happyhero

Hi i have a 1930's mock Tudor house and I am decorating the front. The Mock Tudor effect is done the typical way of having black painted planks fixed to the walls with white painted render in between. There are planks that runs down both sides of the UPVC window (of the bedroom on the first floor) so that they appear to butt up against the window.

I have just removed the one on the right as it had been fitted poorly so that I could refit it but I have found big gaps.

The gap from the actual frame of the window to the brick wall is about 1 1/2" and at the bottom of the window on this side at sill level there is a bit of brick missing about 4" square in the outer cavity. There is also a little bit of expanding foam at the top corner and bottom corner of this side plus someone has put some rag in there.

I have removed the rag and tidied up the foam for now.

We have almost no damp at all in our house it is very dry but in the room behind this area of the window you can see the wall is stained with a small amount of damp . It appears to originate from the outer cavity i.e. the furthest into the reveal right by the window frame.

So the black plank outside was hiding this gap when in place.

My guess is the damp is not because anything is tracking across the cavity particularly but more to do with the fact because the plank was fitted so poorly it allowed rain to run down the wall and behind the plank and thus soak the side of the window frame and so get to the plaster inside. But correct me if you think different.

The window is fixed with those screws that come with the grey rawlplug already on them.

So my questions, is the foam crossing the cavity ok?

I assume foam will NOT absorb water and thus let it travel from one side of the cavity to the other?

Should I fill the cavity between the window and the outer bricks with anything, i.e. should I spray foam in it from top to bottom (maybe this will help as it will stop any water being able to rest or travel over the top of the bottom foam)?

What should I do with the 4" gap at sill level can I spray foam this or should I brick that up as it will be hidden?

By hidden I don't mind if it is foam but that doesn't mean I want a bodge job that may cause problems later.

The gap beside the window seems wrong to me even though it is hidden so I feel i should do something here, but what, bear in mind the fixing screws cross this cavity.

Any help appreciated.

thebaldwindowfitter

Is the damp showing below the window ie below the window board if there is one or is it also in the reveals above the window board