A basement with a seven-foot ceiling and a bulkhead every four feet feels like a parking garage. Worse, in a basement apartment, a bulkhead in the wrong place can make a room fail the ceiling height rule.
The good news: most bulkheads are a planning problem, not a law of nature. Here is how to route ducts so the basement keeps its height.
Run the main trunk alongside the steel or wood beam, so one bulkhead hides both instead of two.
Where joists run the right way and the design allows it, branch ducts can live between joists instead of below them.
A central furnace or air handler means shorter runs and smaller ducts.
Put the unavoidable ones where nobody cares about ceiling height.
Ducts sized from the room-by-room heat loss are often smaller than the habit-sized ones. Smaller ducts, smaller bulkheads.
Returns take space too. Plan them with the supply, not after.
Basement suites have minimum ceiling heights, and ducts and beams count against them. A bulkhead across a bedroom can turn a legal room into a storage room. See the basement apartment checklist.
The cleanest suites often have no supply ducts in their ceiling at all: a ductless heat pump for heat and cooling, and a small HRV for fresh air. See suite heating options.
Measure the ceiling height under your beam and your lowest ducts before you design the layout. If you are already close to the minimum, the HVAC plan has to work around it.
Heat from the floor, nothing in the ceiling. Planned before the slab or as a topping.
For a suite or a rec room, heat and cooling with no ducts at all.
Flatter rectangular duct can save inches, if it is sized to carry the airflow.
Sometimes the old trunk can be moved to a better line. Cheap before framing, expensive after.
The room-by-room heat loss tells you how much air each room needs. That sets duct sizes, which sets how big the bulkheads have to be. Then the duct design shows the route.
If the basement is being finished as part of a permit, the ventilation summary (RMVDS) goes with it. See basement finishing permits.
Finishing a basement? Send us the floor plan before framing. We route the ducts so you keep your ceiling.
Get Free Quote →Plan the duct routing before framing. Run the main trunk along the beam so it shares one bulkhead, use joist spaces for branches where the design allows it, and put the furnace near the middle of the house so runs stay short.
Yes. Basement suites have minimum ceiling heights, and ducts and beams count. A bulkhead in the wrong place can make a room fail. See the basement apartment checklist.
Often, for branches, if the design allows it and the joists run the right way. Joists running the wrong way are why trunks end up in bulkheads. The duct design shows what fits where.
Low-profile rectangular duct can save height, but it still has to carry the airflow the rooms need. Squash a duct too flat and the far rooms go cold. Size it on paper first.
Yes. Radiant floor heating in the slab, or ductless heads for a basement suite, can leave the ceiling clean. You still need ventilation, which can often be routed more easily.
Before framing the basement ceiling. Once the drywall is up, the only way to fix a bad bulkhead is to tear it down.
Send your basement plan with ceiling heights and beam locations. We size the ducts from the heat loss and route them to keep bulkheads to a minimum.