Closing Cavity Walls

i believe the question is not answerable without any details (in an engineers point of view)

Even though this is non-technical answer,

For trying to help you, i have just found these typical sections about insulation of cavity walls?

http://www.plymouthfoam.com/building_products/duraspec/images/cavitygeneralimage.jpg

http://www.achfoam.com/ACH/media/images/Sheathing/Cavity%20Wall2.jpg

Hi James

Wessex estimating item GJ002 Closing Cavities not exceeding 75mm wide:

102.5 Facing Brickwork:
at jambe or end of wall 0.40 lab hours per m
at sill 0.55 lab hours per m
at top of wall 0.30 lab hours per m

As I advised earlier - get the disc from RICS bookshop.

Best regards

Mike Testro