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Merlex representatives are fielding an increasing number of questions about how to build energy-efficient stucco walls.  These systems have existed for decades, but are getting a boost from the California Title 24 energy efficiency standards that went into effect on July 1, 2014.

CI application

Insulex, Continuous Insulation One Coat Stucco System


Some of the most common questions we have been asked are:


  • How can I use stucco over “CI” (continuous insulation) foam board?
  • Will CI stucco systems (a.k.a. 1-coat stucco) be less durable than traditional 3-coat stucco?
  • Is there a cost difference between 3-coat and 1-coat stucco?
  • Are contractors in California trained to properly apply 1-coat stucco?
  • Does 1-coat stucco have a strong “bang for the buck”? That is, will 1-coat stucco cut energy usage significantly more than all other design alternatives with the same cost?
  • Can 1-coat stucco go over open framing?
  • Does 1-coat stucco have a fire rating?
  • What if we combine 1-coat stucco with other siding materials and there are different cladding thicknesses on the wall?
  • What if the foam board fasteners miss the studs?
  • What happens to windows and accessories like weep screeds when the thickness of the stucco increases?
  • What alternatives are there to 1-coat stucco if I decide not to use it?


Merlex’s President and Vice President are touring the State right now with an informative presentation on this subject, and would welcome the chance to present to architects and builders interested in these and other questions.  The industry needs to learn more about 1-coat stucco, such as Merlex Insulex, and what it can do to help them build more energy-efficient buildings.






Continuous Insulation cutaway


Insulex product bag