4620 Ultra Concrete Underpad

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4620 Ultra Concrete Underpad


Our rFOIL 4620 Ultra Concrete Underpad is an outstanding reflective insulation and puncture-resistant vapor barrier.

rFOIL 4620 Ultra Concrete Underpad consists of a double layer of polyethylene bubbles sandwiched between an aluminum surface and a clear polyethylene sheet. It is ideal for many under-slab insulation applications because a protective film is applied to the aluminum surface virtually eliminating the risk of corrosion.

Using rFOIL 4620 Ultra Concrete Underpad in your construction project can improve the efficiency of radiant heating systems and significantly decrease heat loss to the ground below when properly installed with the clear side facing upwards.

rFOIL 4620 Ultra Concrete Underpad provides exceptional thermal value and a strong, permanent vapor and radon barrier.

Use rFOIL 4620 Ultra Concrete Underpad as a cost-effective alternative to rigid foam insulation.


  • Concrete Underpad Improves Radiant Heating System Efficiency  
  • Provides Continuous Thermal Break Below the Slab  
  • Reduces Radiant Heat Loss  
  • Strongly Bonded to Resist Delamination  
  • Multi-Layer 8.4 mil Bubble Core  
  • Unaffected by Lime and other Corrosive Chemicals, often Found in Concrete  
  • Quick, Safe, and Easy Installation Results in Lower Labor Costs  
  • Keeps Underground Moisture Away from Slab  
  • Easy to Cut and Configure around Obstructions  
  • Durable and Long-Lasting Polyethylene  
  • Ideal for Edge-Slab Insulation and Expansion Joint  
  • Approved Vapor Barrier


Standard roll sizes of
  • 48” wide by 125’ long
  • 72” wide by 125’ long
  • 96” wide by 125’ long
  • Also available in 500, 750, and 1000 sq. ft. rolls.

  • rFOIL 1620 has a 14.2 mil multi-layer bubble core compared to 4320 (8.4 mil bubble core) and 4620 (11 mil bubble core).
  • rFOIL 1620 has a 140 psi compression strength compared to 4320 (70 psi) and 4620 (90 psi).
  • rFOIL 1620 single reflective layer is covered by a durable and protective laminate compared to 4320 and 4620 where the reflective layer is exposed.
  • Choose rFOIL 4620 or rFOIL 4320 if higher reflectivity and lower emissivity is desirable or if compression strength and durability is not of prime importance; otherwise choose 1620 Ultra CBF.

Product Documents

View 4620 Technical Data Sheet
View Reflective Insulation 3-Part Guide Specification
View rFOIL Product Specifications (HVAC)
View R-Value Application & Airspace Requirement Guide (HVAC)
View R-Value Application & Airspace Requirement Guide (COMPLETE LISTING)
View rFOIL Standard Warranty Documentation

Applications for 4620 Ultra Concrete Underpad

View Radiant Heating In a Concrete Floor
View Radiant Heating In Snow Melt
View Radiant Heating Over Wood Floor
View Under Wood Sub-Floor