Whilst removing all the tiles in my bathroom to refurb (double layer, nice work!!) I have discovered on the side where the window is situated that there is a small amount of movement on the inner wall (breeze or thermalite, not sure which) the wall is very small in its width (approx 1.7m) and the movement is occuring on whats left of the wall immediatelly to each side of the window on the vertical setions. I think whoever installed the window was very rough when they knocked the inner down. I have good access to the outer brick skin which is very soild. What's the best way to stabilise this without going to the hassle of wall ties. Can I install a vertical wood batten screwed to the outer and inner brick to stabilise? any comments appreciated