Proper Brands Marijuana Cultivation Facility: St. Louis, MO


Client: Proper Brands
Project: Cannabis Cultivation and Manufacturing Facility
Floor Area:
56,000sf with 20,000sf grow space
Construction Schedule: Completed 2021
General Contractor: Kadean Construction


Engineer of Record (EOR)
Installing Mechanical Contractor




Wiegmann Associates tapped into their extensive experience engineering complex systems for temperature and humidity-controlled specialty projects as the Mechanical Engineer of Record for Proper Brands’ state-of-the-art 58,000-square-foot cannabis cultivation facility.

The project involved converting an existing building into a specialized cultivation facility with strict temperature and humidity requirements. Air purity had to be monitored and regulated and odors mitigated. 

Wiegmann designed, coordinated, and installed the HVAC components for the office, propagation rooms, vegetation rooms, flower rooms, trim rooms, dry rooms, extraction rooms and a full-service kitchen. The main office and non-grow areas are served by DX rooftop units while the grow rooms are served by a chilled water system with in-room dehumidification. Wiegmann designed and installed the compressed air piping system and also installed the CO2 enrichment distribution piping, fertigation equipment and a drip irrigation system.

Proper Brands is one of the first cannabis cultivators in Missouri to receive commencement for growing and manufacturing of medicinal marijuana by the Missouri Department of Health and Senior Services.



A primary project challenge was the restrictive space limitations. A movable vertical rack system doubled the amount of flowering canopy area. Because grow rooms require a large amount of cooling to offset the heat produced by the intense lighting, Wiegmann’s engineers had to effectively design systems to provide the owner with the most amount of growth space possible. 

In early 2020, increasing construction and material costs put the project in danger of not moving forward. Wiegmann collaborated with the design team and Proper Brands to ensure the HVAC system aligned with the owner’s original budget and timeline.