1/2 inch nstruction ground plastic ver pads-HDPE sheets 4 Typical R‐value per inch Inches for R‐10 Inches for R‐15 Expanded Polystyrene 4.0 2.5 3.75 What materials can be used? Extruded Polystyrene 5.0 2.0 3.0 Polyisocyanurate 6.5 1.5 2.3 11 Expanded Polystyrene (EPS) Extruded Polystyrene (HENAN OKay) Polyisocyanurate (ISO) Check with manufacturer for approval for ground ntact