ROXUL TOPROCK® DD Plus is a high-density, bitumen-coated stone wool commercial insulation board for low-slope roof applications. It has an R-value of 3.8/in at a mean 75°F temperature that increases at cold temperatures and decreases slightly at warmer temperatures, making it useful for the extreme temperatures of a roof deck. It can be used as the thermal insulation or as an insulating coverboard in torch, hot mopped or self-adhered membrane systems.

It provides added benefits to the roof system through its added fire resistance, FM 4470 NCC rating, sound absorbency, dimensional stability and impact resistance. It is available in 2-6” thicknesses in 4’x4’ boards for easy installation.



Designed for commercial and industrial low slope roof insulation applications. It is suitable for both new building and re-roofing applications. TOPROCK® DD Plus is intended as the top layer of a roof system in conjunction with torched, mopped or self-adhered membranes. See Technical Data and individual product specification sheets for details.

It can also be used as a coverboard over top of other thermal insulations. To learn more about how this can add value to your project, click here.


  • Non-combustible
  • Will not warp or cup
  • Dimensionally stable
  • High impact resistance
  • Low moisture sorption
  • Non-corrosive
  • Stable R-value
  • Fire resistant
  • Excellent acoustical properties
  • Made from natural & recycled materials
  • ROXUL can contribute to earning LEED® points
    Click here to estimate the effects of using ROXUL insulation on your next commercial roofing project by using our interactive Energy Cost Calculator. See how decreasing R-value affects the energy performance of your building.