I have finally given up on blown beads cavity insulation because it is not the done thing in mid Lincolnshire. When 9 out of 10 pro builders look perplexed at the mention of beads and say "isn't that what they retro fit into older properties", when the face of one's chosen SAP assessor turns grey at the mention of beads and when the building control inspector pops over for a social chat and assumes I will be using cavity batts, then the message is clear.   I will soon be bringing my ex