XPS vs EPS

As seen in the Milwaukee Area

XPS vs EPS

Based on the principles of science and engineering, Dow Styrofoam XPS outperforms EPS, and delivers maximum energy savings.
XPS Performance Data Summary

77% more density. The higher the density:

  • The greater the moisture resistance
  • The higher the R-value
  • The greater strength
  • The tighter the structure (closed cell)

28% higher R-value

  • The higher the R-value, the greater the resistance to heat flow
  • One cubic inch of Styrofoam XPS contains millions of tiny cells
  • Unique closed-cell structure helps block transfer of heat and cold
  • Provides maximum energy savings

250% higher compressive resistance

  • Compressive Resistance—the amount of force needed to deform the XPS insulation
  • The higher the compressive strength, the harder it is to damage the insulation
  • A higher compressive strength helps keep walls more uniform and straight when placed over existing siding

Effectively handles water vapor permeance

  • Water Vapor Permeance—the amount of water in the vapor state that passes through a product or system
  • EPS insulation has a 5.0 perm rating
  • Vinyl siding has a .05 perm rating
  • When a substrate is laminated (such as EPS and vinyl siding), it takes on the properties of the lower of the two—which would be the .05 perm of vinyl siding
  • Dow 3/4″ T&G XPS insulation has a   perm of 1.1—it will not trap vapor moisture
  • Dow XPS is not attached to the siding so  it does not take on the .05 perm
  • By maintaining its consistent perm rating,   Dow XPS allows harmful moisture to escape the home
  • Dow XPS also creates an effective drainage plane, allowing rain and  wind-driven water to escape quickly through siding weep holes
  • Provides superior moisture resistance
    • Water Absorption—the volume of a liquid that becomes trapped in a product
    • 3/4″ XPS takes on .1% water vs. EPS at 4.0%
    • For every 1% moisture absorption, you lose 5% of   the R-value
    • If the R-value of 3/4″ of Type I EPS = 2.7 per inch, it will reduce to 2.16 after taking on 4.0% moisture
    • Wet insulation loses thermal integrity and facilitates energy loss
    • XPS’ high density and closed-cell structure block moisture penetration
    • In a water vapor freeze/thaw test, XPS retained 98% R-value!

Test Data Proves—XPS Insulation Delivers on Every Key Factor

  • Higher density
  • Higher R-value
  • Higher compressive strength
  • Effectively handles water vapor permeance
  • Superior moisture resistance