Interior side of window frame directly touching stone sill

[j_s]

Hi guys, taken out all plasterboard of the final room in my house and found that although some plastic Packers are used they are 1mm thick and only packed on the edges of the frame. The stone sill is reconstituted and there are 2 of them butted to each other. Towards the middle they probably rise very slightly and now the inside of the window frame is touching the sill and a very serious cold bridge. No wonder when I had no mvhr there was so much condensation in the centre of the window at the bottom!

 

3 potential ways to solve

1. New window and sized better, can get new cavity closers in easily if so and foam the gap along with tape to seal completely.

2. Refit the window but not sure if I can move it up much at all. 

3. Grind a few mm away on the inside of the sill under the window very carefully with a brick blade on the multitool ,can then get cavity closer in and foam and tape, risky though.

 

Window is 2.3m wide by 1.2m high, aluminium so gets very cold in the winter due to the cold bridge

 

Any thoughts guys?

 

Thanks

James

Edited June 26, 2019 by j_s

[j_s]

We ended up using a multitool with a brick cutter blade to grind away the cill from the inside and now the window doesn't sit on the cill any longer. I have now foamed the gaps and we will be adding the cavity closers in the next week and then I'll foam any further gaps and then tape.