Modern architectural homes often present HVAC duct design challenges not typically found in traditional residential construction. Features such as LVLs, steel beams, small mechanical closets, mechanical mezzanines, long exhaust runs, linear slot diffusers, and inaccessible structural areas can significantly complicate duct routing.

These architectural elements are often necessary to achieve the modern aesthetic envisioned by the architect. However, they can create significant restrictions when designing an efficient HVAC distribution system. Because of these constraints, the labor required to complete a proper Manual D duct design may double or even quadruple compared to a conventional home.

Due to this complexity, pricing for duct design on modern homes is customized. The additional cost can range from $0.10 per square foot up to $0.75 per square foot for extremely complex designs.

Ways to Reduce Manual D Design Costs (and your installation costs)

• Utilize open web joists whenever possible (NOT TJI's or LVL's)
• Use larger open web joists (20–24 inches tall)
• Drop LVLs and steel beams into wall cavities to allow ducts to pass above
• Provide mechanical rooms with a minimum of 350 cubic feet
• Install multiple mechanical rooms in larger homes
• Spread mechanical rooms throughout the structure to shorten duct runs
• Consider implementing a crawlspace instead of a slab