Premium lightweight blended stucco with class-leading ease of application, efflorescence resistance and performance. High flexural strength with less shrinkage cracking than typical stucco products.


  • Lightweight
  • About 60% lighter than traditional stucco
  • More bags per truckload
  • Lighter weight on the wall
  • Easier to carry and mix
  • Easier to apply
  • Less cracking
  • Less efflorescence
  • Insulation qualities, nearly five times the R-value of stucco
  • No harmful silica


  • Application Temperature: 40°-110°F (5°-43°C)
  • Working Time: 1 hour
  • Set Time: 1-2 hours
  • Cure Time: 48-72 hrs at room temperature, working and drying time will vary with temperature and humidity.


Air and substrate temperature for application of Cemplaster Fiberstucco L must be 40°F (5°C) or higher and must remain 40°F (5°C) or higher for a minimum of 24 hours. Provide temporary protection to protect the wall system from damage until permanent flashings, caps and sealants are installed. Store materials in a dry place, within prescribed temperature limits and out of direct sunlight. Working and drying times are based upon normal room temperature conditions and will vary with temperature and humidity.


Preparation – The substrate must be approved by Master Wall Inc.®, clean, dry, structurally sound and free of efflorescence, oil, grease, form release agents and curing compounds or anything that would affect bond. Painted surfaces are not acceptable and must be removed or metal lath applied.

All sheathed applications must receive a minimum of 2-layers code approved asphalt felt or equivalent.

Prepare smooth or non-absorbent solid substrates by one of the following methods or a combination; Sandblasting, chipping or acid etching, A dash-bond coat applied forcefully, Bonding compounds such as Master Wall® Stucco Ad-Liquid or BA57, Furred or self-furring metal plaster bases as per ASTM C1063.


  • 3/8” (9.5 mm) thick: 20 sf (1.8 sm)
  • 1/2” (12.7 mm) thick: 15 sf (1.4 sm)
  • 3/4” (19 mm) thick: 10 sf (0.9 sm)
  • 7/8” (22 mm) thick: 8.6 sf (0.8 sm)

*All coverage is approximate and depend upon substrate, details and individual application


  • 50 lb. (22.7 kg) moisture resistant bags.
  • Shelf Life: 6-12 months
  • Storage: Protect from weather in a cool dry area, with low humidity.


  • ASTM C109 Compressive Strength – 2500 psi
  • ASTM E330 Wind-rated Assemblies – 67-183 psf Ultimate Load
  • ASTM G155 Accelerated Weathering – Pass
  • ICC-ES AC11 Durability Testing – Pass
  • ASTM E136 – Noncombustible
  • ASTM C926 compliant following standard practices
  • R-Value: 0.46/inch
  • Recommended Pump: Graco 340e or equivalent
  • Recognized in IAPMO UES ER-0381

Mixing Instructions: Proper mixing is critical for performance and workability. Start with six (6) quarts of clean water (water amount is approximately 28–30% of dry mix), add entire bag of Cemplaster Fiberstucco L and mix at LOW SPEED for 3 – 5 minutes. DO NOT OVER MIX! Mixing should be done carefully to minimize air entrainment, as high air content will reduce performance. Allow to slake (rest) for 7 to 10 minutes. (Lightweight aggregate will continue to absorb water.) Gently re-mix and adjust consistency with additional water if necessary for workability.

Direct Applied to Masonry: Dampen absorptive masonry just before application with water or Master Wall® BA57 Bonding Agent.
Scratch Coat: Apply Cemplaster Fiberstucco L with sufficient pressure to key into and embed the metal lath (if used). Apply sufficient material, approximately half the Cemplaster Fiberstucco L ground thickness to cover the metal lath and to permit scoring the surface. Score the Cemplaster Fiberstucco L horizontally upon completion of each panel in preparation for brown coat if a “double back” application of a wet scratch and brown coat isn’t being used.
Brown Coat: as soon as the scratch coat is firm enough to receive the brown coat without damage, apply the brown coat with sufficient pressure to ensure intimate contact with the first coat to an approximate thickness as needed to bring the Cemplaster Fiberstucco L to a uniform thickness that matches the grounds of the accessories. Use a rod or straight edge to bring the surface to a true, even plane. Fill depressions in plane with Cemplaster Fiberstucco L.

After the Cemplaster Fiberstucco L has become slightly firm float the surface lightly with a Darby or wood float to densify the surface and to provide a smooth, even surface.

Cure following ASTM C926 guidelines or other method acceptable to the design professional for 48-72 hours. Mixes with Master Wall® Stucco Ad Liquid do not need moist curing.

Allow to cure until clean, dry and hard before finishing:

  • Typically 5-7 days if no Master Wall® Stucco Ad Liquid is used, pH of 13 or less if Primecoat is used, pH of 10 or less for Superior Finishes.
  • After 72 hours if Master Wall® Stucco Ad Liquid is used provided the Cemplaster Fiberstucco L is clean, dry and hard.
  • After 24 hours if using a leveling base coat (LBC).

Tools and equipment can be cleaned with soapy water while the Cemplaster Fiberstucco L mixture is still wet.

Mineral Name/Chemical Formula/Approx. Wt/ %
Gismondine/ CaAl2Si2O84H2O/<5 Plagioclase feldspar/(Na,Ca)Al(Si,Al)3O8/<3 Quartz*/SiO2/<0.1 Cristobalite*/SiO2/<0.1 “Amorphous”/?/>65
“Unidentified”/?/<5 *Forms of “crystalline, free silica” Hazard: This chemical is not considered hazardous according to the OSHA Hazard Communication Standard 2012 (29 CFR 1910.1200). WARNING: Products containing crystalline silica (airborne particles of respirable size) are known to the State of California to cause cancer. For more information go to VOC: Less than 50 g/L.


  • Self-furring Metal Lath
  • Concrete
  • Brick
  • Masonry
  • Others approved in writing

Information contained in this product data sheet conforms to the standard detail recommendations and specifications for the installation of Master Wall Inc.® products and is presented in good faith. Master Wall Inc.® assumes no liability, expressed or implied as to the architecture, engineering, or workmanship of any project. This information may be concurrent with, or superseded by other applicable documents, such as specifications and details. Contact Master Wall Inc.® for the most current product information. ©2022 Master Wall Inc.®