Foam Vs Felt Underlayment for Concrete Sub Floors

For an ongrade concrete sub floor under laminate floor, is foam or felt/fiber underlayment better?

On grade concrete is tricky. The proper thing to do is to test what the concrete is emitting for moisture vapors. Find the suitable floor underlayment that will perform to those emissions. Foam underlayment is made from resin/petroleum based products which will block moisture inherently. Fiber/Felt Underlayment is made from recycled materials and will help…