Missing Radon barrier

[cbk]

Hi guys I’ve discovered that dpm layer under slab should have been a Radon barrier and looks like a regular 1200g membrane was used.  Trying to figure out best option to resolve and keep BCO happy. UFH and screed have been laid but not yet the finished  floor of porcelain tiles.  Is there an option to put radon barrier on top of screed and under tiles?

 I’ve also read that if you have MVHR then this can be sufficient to remove any potential Radon and avoid the need for a Radon barrier under the slab.  Any advice appreciated.

[Radian]

What about using a gas barrier paint ?

 

[Iceverge]

Provided all joints were taped adequately the 1200 guage membrane will be fine as a Radon barrier. 

 

[Redbeard]

Did/does BCO require a radon sump as well? The few jobs I have done which required a membrane also req'd a sump.