multifoil with non foil faced boards?

[syne]

I'm kinda stumped on this one,

I've got an opportunity to buy a lot of non foil faced insulation at a very good price.
As I understand it the foil helps with the radiation side of heat loss, acts as a vcl when taped and so is somewhat beneficial.
Would a multifoil (yes, yes I know..hiss boo etc)be a worthwhile addition ?

iirc the multis only ever got to their claimed values when twinned with pir anyway. so I'd end up with the 'reccommended' install method for that by accident, on top of/getting a <0.17wm2k rating before the foil.

Or should I just add a vcl to the boards and not bother with the foil?

 

[syne]

Any opinions?

An alternative would be foil backed plaster board if taped would this act as a vcl or would I need a separate layer of another material...