Will try and make post simple.
Metre square of 100mm soft wood equals K of .130, R of .77 and U of 1.29W/m2K
Metre Square of PIR/PUR equals K of ,022, R of 4.54 and U of .22W/m2K
Unless over boarding across studs with insulated plasterboard always allow and deduct a percentage for repeated cold bridging of timber studs or calculate heat loss of studs independently and then deduct from R value
Regards oldun
Metre square of 100mm soft wood equals K of .130, R of .77 and U of 1.29W/m2K
Metre Square of PIR/PUR equals K of ,022, R of 4.54 and U of .22W/m2K
Unless over boarding across studs with insulated plasterboard always allow and deduct a percentage for repeated cold bridging of timber studs or calculate heat loss of studs independently and then deduct from R value
Regards oldun