Radon protection barrier over sanitary slab, with asphaltic sheets

Radon protection barrier over sanitary slab, in ground with a reference radon exposure level of 300 Bq/m³, with a sheet of bitumen modified with APP plastomer, LA-30-AL, with aluminum reinforcement, unprotected surface, and radon gas diffusion coefficient of 1x10-13 m²/s, non-adhered. Installation on site: with overlaps, on the upper face of the slab, and protection with an anti-puncture layer of polypropylene-polyethylene geotextile, (125 g/m²). Expected radon exhalation through the protection barrier: 0.000104 Bq/m²·h. Includes reinforcement strip of bitumen sheet modified with SBS elastomer, LBM(SBS)-30-FP, for perimeter resolution.