I appreciate this is resolved for RA, but another option for anyone searching for similar in the future:   We have 4 Columns of the original cow-shed structure (holding up the roof) that drop into our thermal envelope, and I had to add additional goal-post bracing between each pair as I wanted to move the original racking braces to allow other areas to be opened up:     We boxed these in with ply and then used a closed-cell spray-on PU foam, (Elastospray 1629/1 fro