In the first part of this series on cannabis cultivation buildings, the founder of MJ12 Design Studio, Sam Andras, described the main challenges that building selection poses to cannabis growers, also pointing out the different aspects to take into consideration when it comes to choosing a structure for large-scale cannabis growing. In the last article, Sam discussed pre-engineered metal buildings, and their pros and cons. Today, he is going to explore conventional steel buildings and heavy timber and historic mill buildings. If you have missed out the first part, click here to catch up!
Conventional Steel Buildings (CSB)
CSBs generally have standard bay spacing which can be 30’ or more in each direction. In fact, these buildings can easily clear span much larger areas. Walls and roofs for CSBs are typically more traditional materials such as brick veneer, tilt-up, or pre-cast concrete for walls and roofing systems such as single-ply, EPDM, or built-up roofing. The roofing system will typically be on a concrete or metal deck. In newer buildings a layer of insulation is placed between the deck and roof. Wall insulation is also common with CSBs. Based on use, the design of a CSB can provide a good thermal envelope helping to address odor mitigation and air/pest infiltration. This issue becomes extremely important in states such as Michigan where the building is required to operate under negative pressure. However, there is no standard design with the envelope of CSBs and each should be investigated.
As noted above, CSBs are typically purpose-built designs. This means the design has specific parameters which defined the structural design of the building. The structural capacity of the system may have some additional loads beyond those required by code based on the building’s use and anticipated equipment. As with a PEMB, it is important to understand the capacities of the structure based on the equipment and systems anticipated for use within the facility.
Heavy Timber and Historic Mill Buildings
Issues with heavy timber and historic mill buildings also present a combination of complexities. Heavy timber buildings typically have smaller bay spacing than steel buildings. The use of wood within a high humidity environment is also a negative. The structural capacity of heavy timber can generally accommodate the loads of ceilings, cultivation lighting, ductwork, sprinklers, and fans which is a plus. Roofing systems on these buildings are typically similar to a CSB, thereby a roofing system over decking. If modernized, the roofing system may include insulation. Walls are typically multilayered brick and, in many cases, have mortar that has deteriorated over time. These wall systems can allow moisture penetration to the interior of the building. Additionally, there is generally no insulation on the exterior walls of these types of buildings.
Another consideration, most heavy timber and historic mill buildings will include an abundance of windows. If original, these are single sheets of glass in steel or wood frames. Addressing these windows is a must for a cannabis facility, yet not always easy. If the facility is within a historic zone, on the historic register, or falls under any state / federal historic landmarks modification of the exterior, and interior, will be governed by the Department of Interior standards.
When considering the purchase of an existing building we recommend owners consider retaining a team for development of a Property Condition Assessment (PCA). MJ12 Design Studio provides ASTM E2018-15 Property Condition Assessments for clients in a multitude of industries. The PCA evaluates all aspects of a building as related to its current or project use. Existing conditions are documented as excellent, good, fair, or poor. Deficiencies are identified and corrective measures proposed. For each deficiency, a cost is provided along with a suggested timeline for correction of the issue. The findings, recommendations, timelines, and cost opinion are presented in a Property Condition Assessment Report. A PCA provides an owner with a solid foundation for making an educated and informed decision on the purchase of a building.
For more information:
Mj12 Design Studio
7430 East Caley Ave
Centennial, CO 80111