Second floor master den was converted to a master bath. New plumbing and or wiring extends the length of two downstairs bedrooms, bath, and laundry room. The downstairs bedrooms and bath already have heat ducts extending into the rooms so would like to lower the ceiling to cover the heat ducts as well as the new plumbing and wiring. What's the best way?
There are probably two best ways to lower the ceilings in your situation: one would be the most economical -- a suspended ceiling; and the other the most attractive -- box down the room height. However, the first issue to address would be the existing ceiling height of your first floor and how far into that space your mechanicals encroach.
Most jurisdictions permit a minimum ceiling height of seven feet for residential dwellings and even a few inches lower if certain requirements are met. But keep in mind that that is a very low ceiling for an entire room. Most new homes have eight- or nine-foot ceiling heights on the first floor and some can extend much higher. While a ceiling that's seven feet high might meet building code, it may create a claustrophobic effect when using the room.
If your mechanicals extend lower than seven feet, this building code excerpt from the City of Portland's website provides some options for boxing in the pipes and duct work and still meeting code. Check with your local jurisdiction for minimum ceiling heights in your area, but they should be about the same. Most building officials use a national code with minor adjustments for local needs.
As to the methods, a suspended ceiling involves attaching metal wires to the framing members of your existing ceiling that then support a series of tracks that are used to hold tiles. The tiles may be made of gypsum, polyurethane, or metal and are available in numerous styles and colors. Costs can range from gypsum systems with standard tiles that are very budget-friendly to high-end configurations that use tin or copper tiles.
The advantage of a suspended system is that the ceiling height is very flexible. It's determined by the length of the hanging wires. Many commercial buildings have suspended ceilings as they allow easy access to the ducts, pipes, and wiring they hide. This association is why some homeowners prefer not to use suspended ceilings in their homes, but there are many tiles that have residential styling.
Lowering the entire ceiling by boxing down the room heights is the same as building a bulkhead around the mechanicals, but extending it across the entire area. You're basically building a new ceiling that would then be covered with sheetrock or another finish. Depending on the size of the rooms, this option could become costly. Don't forget that with both options all ceiling light and fan boxes may also need to be lowered.