Door frame depth for 120mm stud wall

[iMCaan]

Hi all,

 

We have a 120mm (tape measured) stud partition (70mm MF with timber inside, 2x11mm OSB sheets, 2x12.5 plasterboards = 117mm). Not sure what I should allow for skimming, probably 6mm (3mm either side). 

Can someone please tell me what depth of door frame I need to order?

 

Thank you

[nod]

3 mil either side 5 is still ok 

[iMCaan]

Thanks @nod

 

Is that 3mil before or after skimming?

 

Thanks

[nod]

Before

[Thorfun]

for our 140mm TF openings plus 30mm for plasterboard either side our chippie made our door linings from 25mm MDF as to buy something ready made would've been hard to do.

[iMCaan]

Thanks