Replacing window board on PVC bay

[Vector771]

I'm in the process of insulating my bay window. I've been taking the plaster off back to brick and want to remove the plastic window board and replace with wood. Can anyone advise how these are attached to the main window frame? I want to be sure it's actually removable before I damage it trying!

Also, the plaster appears to get very thick just bellow the window as shown in the pic. I assume the window frame rests on brick/a lintel and they've just plastered to fill the gap the inner course of bricks below? I was thinking the remove enough of this to be level witbt he bricks below and make good with plaster before putting the pir insulation on. Does that make sense?

 

[Vector771]

I've got rid of some of the plaster underneath and the window board appears to extend in beneath the window surrounds so I don't think its an easy remove. The insulation I'm adding is going to stick out further than the current window boards - any suggestions on how to extend them if I can't replace them?

 

[crank39]

It looks like laminated duraboard and likely stuck down with silicone or no nails. If you end up leaving it place you can cap over it with a wider capping board

 

[Vector771]

It looks like laminated duraboard and likely stuck down with silicone or no nails. If you end up leaving it place you can cap over it with a wider capping board

Thanks! I decided to go for it with the removal. There was a thick (~8cm) deep chunk of plaster above the cill that the window board was resting on, then it was glued onto the frames at the back as you said. Came off easily once the plaster was gone!

I'm going to add timber to the gap left between the cill and the bricks before getting celotex on there