Corner damp - windows plastered correctly?

[Louis.]

Noticed there was an ingress of damp in the corners of the upvc windows in the bedroom. It's clearly been doing it for a while as they were mouldy but the previous property owners didn't address it.

I dug out the plaster as the rooms in decoration mode to see if I could access the corners and see if the sills have been siliconed. Unfortunately I don't have enough visibility so instead pumped them full of expanding foam after reading some similar threads. Unfortunately this didn't solve the problem and I've dug it out again.

What I did notice is that the side trims have been plastered into the walls, is this normal?

I'm planning on cutting more of the plaster away, potentially going all the way to the top? Then seeing if I can see with water ingress.

All the exterior silicone appears to be OK but it is filthy.

Any help appreciated.

 

[Wayners]

Metal foam gun in building section of B&Q is £10.
Not store. In the building section...
Put mastic nozzle on end and ram in from outside up edges of window 150mm and all the way along bottom.
Foam up.
I push plastic nozzle right in to fill up with foam.
Cut back then window mastic to finish.
Stick some foam on inside gaps.
Fill and make good.
Done a few with no call backs. Only way I know. Foam sticks to wet and blocks water forever

 

[Louis.]

Metal foam gun in building section of B&Q is £10.
Not store. In the building section...
Put mastic nozzle on end and ram in from outside up edges of window 150mm and all the way along bottom.
Foam up.
I push plastic nozzle right in to fill up with foam.
Cut back then window mastic to finish.
Stick some foam on inside gaps.
Fill and make good.
Done a few with no call backs. Only way I know. Foam sticks to wet and blocks water forever

I'm going to dig the plaster out all the way up, so presume I can do this from the inside?

I already filled it with foam but it came back pretty fast.

 

[Wayners]

With foam you need to get it right in. I mask up as foam wrecks upvc. Any over spill will come off with masking.
I hang plastic over a window below if there is one.
Like I said. Get plastic mastic nozzle and ram on end of foam gun and stick in edge of frame.

When I was in the states (new Orleans) they only fix windows with foam and no problem even with hurricanes ect. Got chatting to American fitters although foam was never popular here at the time.

Really need plenty around and nothing will gets past.
Seems if you get fitters to fix they just want to supply and fit new window.
Many exterior sills are cut with no ears or cut with ears and mastic around. This also can cause problems vs taking brick out either side so sill fits in the wall.