Merlex Stucco Keeping it Premium since 1963


Exterior Stucco

Name Insulex Concentrate
Type Fiber-reinforced Portland cement exterior plaster for use in continuous insulation one coat stucco systems
Application Method Trowel or spray applied
Product Overview ProductsInsulex Concentrate is a fiber-reinforced Portland cement exterior plaster, ideal for achieving superior energy efficiency. The product may be used in conjunction with various foam substrates to create wall assemblies with higher insulation R-values and improved crack- and water-resistance. Insulex may also be used over wood or gypsum backing and as a scratch and/or brown coat application for a conventional stucco system. Insulex Concentrate is mixed with sand on the jobsite. Insulex Sanded is available with premixed sand for convenience.
  • Achieves greater insulation R-values when used with foam board as a continuous insulation system
  • Allows for higher energy-efficiency and California Title 24 code compliance
  • Available sanded or in concentrate form, to be mixed with sand on the job
  • Allows for accelerated job scheduling due to reduced wait time between plaster base coats
  • Optional 10% post-industrial recycled content
  • Optional recycled aggregate for 33% recycled content and LEED credit
  • Available One-hour Fire Rating with specified assemblies in ICC-ES ESR 2564 report
  • Provides crack- and water-resistance
  • Economical and low-maintenance
  • May be used over a variety of substrates, giving architects and builders design flexibility
  • May be trowel- or spray-applied
Suitable Substrates Insulex is suitable for use with metal lath and foam insulation board, gypsum sheathing, or plywood/OSB systems.
Storage Insulex shall be kept indoors. If stored outdoors, the product must be covered to keep dry and stored off the ground.
Coverage One 80 lb. bag of concentrate will cover approximately 72 square feet at 3/8" thickness (54 square feet at 1/2" thickness).
Mixing Each 80 lb. bag of Insulex Concentrate should be mixed with approximately 4 gallons of water and 16 #2 shovels (200 pounds) of plaster sand. Sand must meet ASTM standard C-897 or C-144. Mix for a minimum of five minutes. Continuous batching is an acceptable practice, but care shall be taken to provide enough time for additional bags added to the batch to mix thoroughly. Do not entrain air by over-mixing or using excessive mixer speed. After mixing, allow material to sit for approximately 5 minutes, and then re-temper by mixing for a short period of time.
Application Insulex is applied by hand or plaster pump. The minimum thickness over any substrate is 3/8 of an inch. Some assemblies may require specific minimum thickness. Consult product specifications and the ICC-ES ESR 2564 report for specific details. Allow Insulex a minimum of 48 hours to dry before applying the final color coat stucco finish. Environmental conditions, such as heat, wind, and low humidity will require moist curing.
Finishes Finish plaster can be applied over Insulex after 48 hours under normal conditions. Merlex Color Coat Stucco (16/20, 20/30, and Santa Barbara Finish) provides optimal bond to Insulex without the need for primers or bonders. Insulex is also suitable for use under Vero exterior lime plasters (, and acrylic plasters are also an approved finish. Follow the finish manufacturer's instructions regarding substrate preparation, application, and curing of finishes over Insulex.
Clean-Up Immediately clean all tools and mixing equipment with water after use.
Limitations Do not apply when surface or ambient temperatures are at or below 40° F/4.4° C or above 100° F/34° C, or when temperatures may fall outside this range within 24 hours of application. Do not apply to surfaces that are contaminated with bond breakers, oils, or other matter that may affect the performance of the product. Do not add additional ingredients to Insulex without specific written approval from an authorized representative of Merlex Stucco.
Warranty Insulex is warranted to perform in accordance with the product specification when used according to application instructions. This warranty is limited to and shall not exceed the total amount paid by the buyer for the product. In no event will Merlex Stucco, Inc. be liable for loss of profits, labor, or special or consequential damages in respect to any claim. The foregoing warranties are in lieu of all other warranties express or implied, including those concerning fitness for a particular use.
Environmental and Safety Merlex Insulex contains Portland cement and is alkaline on contact with water. May be irritating to eyes and skin. Wear appropriate dust, skin, and eye protection. In case of eye contact, flush immediately with water, and consult a physician. Wash hands with soap and water after use and before eating. Keep out of reach of children.
Material Standards Portland cement: Type 1-ASTM C150-56
Hydrated lime: Federal specs SS-L-351 B Type F
Code Compliance Exception Report ER-382