Flexible Ductwork for Historic Home

My 1750 single-family house is currently gutted down to the studs, giving us a clean slate to run brand-new flexible ducting throughout the entire structure. The existing oil-fired, forced-air furnace and tank sit in the basement and will remain as the air-handling core, so every new supply and return line must tie neatly into that equipment.

Scope
• Design and install a complete flexible-duct distribution system that reaches every room.
• Size trunks, branches, supply registers, and returns so the furnace can deliver balanced airflow without excessive static pressure.
• Route, hang, seal, and insulate all flex runs to meet current code and eliminate leakage.
• Leave clear access for future service and any eventual central-air add-on.

Site Conditions
The house is wide open—no drywall, flooring, or ceilings to work around—so layout efficiency and neat strapping are expected. Power, lighting, and a clean staging area are available in the basement for fabrication and assembly.

Acceptance
I will consider the job complete when:
• All supply and return points show the target CFM at the registers.
• Connections to the furnace plenum are airtight and properly supported.
• The entire run passes local mechanical inspection and a basic smoke/leak test.
• The work area is swept and debris removed.

If you have experience with retrofits in older timber frames, knowledge of Manual D or equivalent sizing methods, and can start soon, I’d like to hear how you would approach the layout and timeline.