Composite layup design

[BarendGrobler]

Hey all
When designing a composite layup (after calculating pressures etc and designing the layup accordingly); what safety factor should one allow for production imperfections?
let me explain more clearly: to do an accurate/optimal design I've found it's an iteration between class rules and CLT. Now my question is this, when calculating the layup strength, surely you can't just use theoretical strength values for the layup; surely when building a large boat, the layup will not be as "perfect" as the layups used in material tests to get those theoretical strengths. so how (other than testing on-site produced samples) do you compensate for this in your design; what S.F. is a good rule of thumb, if there is one?