November 1, 2014
Any concrete subfloor/slab where a laminate floating floor system requires a vapor barrier for it.
With that said, even with a radiant heat underfloor system, I'd recommend to choose an underlayment that has a built-in vapor barrier included,
However, since your laminate floor has an existing pre-attached underlayment, you can just opt for a 4 mil vapor barrier plastic sheeting.
As long as the thermostat and radiant floor system was installed correctly, placing a vapor barrier down shouldn't be an issue.
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