Dryvit Primus is a 100% acrylic-modified product, which is field mixed in a 1 to 1 ratio by weight with Portland cement to produce the Primus mixture. Questions? Contact Us.
The Dryvit Primus mixture is used to adhere insulation board to an acceptable substrate and to embed Dryvit reinforcing mesh as part of the base coat for Dryvit systems. The Primus mixture can also be used as a skim coat to produce a smooth level surface on masonry or concrete.
Working Time: After mixing, the working time of the Primus mixture is approximately 1 to 3 hours depending on ambient conditions.
Drying Time: When used to bond expanded polystyrene insulation board to an acceptable substrate, a period of 24 hours must elapse to allow the Primus mixture to form a positive bond. The installed insulation board should not be worked on while the Primus mixture is curing. Drying time of the Primus mixture is dependent on the air temperature and relative humidity. Under average drying conditions [70 °F (21 °C), 55% R.H.], the Primus mixture will dry in 24 hours. Protect work from rain for at least 24 hours. Being a cementitious product, the Primus mixture develops full strength in 28 days.
Testing Information: For individual test data on this product’s properties, refer to the chart included with this document.
Application Procedure: For complete application instructions, refer to the appropriate Dryvit system application instructions.
Job Conditions: Air and surface temperature for application of the Primus mixture must be 40 °F (4 °C) or higher and must remain so for a minimum of 24 hours.
Temporary Protection: Shall be provided at all times until the adhesive, base coat, finish, and installation of permanent flashings, sealants, etc. are completed to protect the wall from inclement weather and other sources of damage.
• Exterior grade gypsum sheathing meeting ASTM C 1396 (formerly C 79) requirements for water-resistant core or Type X core
• Exterior sheathing having a water-resistant core with fiberglass mat facers meeting ASTM C1177
• Exterior fiber reinforced cement or calcium silicate boards
• Unglazed brick, cement plaster, concrete or masonry
• Galvanized expanded metal lath 2.5 or 3.4 lbs/yd² (1.4 or 1.8 kg/m²) installed over a solid substrate