Drop ceiling

While we are on the subject of framing, there are a few more carpentry tasks competing for my attention. One of them is the installation of drop ceilings.

The drop ceiling is needed to accommodate all the new utilities we installed on the first floor. These include the ductwork for the Energy Recovery Ventilator (ERV) and the PEX tubing for the radiators. We still have to add the electrical conduits.

The insulated PEX runs and forthcoming electrical conduits have a low profile and only require a clearance up to one and three-quarter inches. The ductwork for the ERV, six and eight inches in diameter, are a different story.

The framing

Only the master bedroom has an eight-inch diameter duct and thus requires a drop ceiling with a clearance of 12 inches. On each short end of the bedroom we mounted a 2 by 4 with joist hangers 16 inch on center, into which we placed the drop ceiling studs.

The other rooms with ERV ductwork have the six inch diameter kind, which requires a clearance of 9 inches. I had it easy and could attach the 2 by 4’s for the drop ceiling directly to the wall studs because they lined up with each other across the room.

Span support

The span of the 2 by 4’s for the drop ceiling is anywhere between eight to 12 feet. That is too much considering that I will hang heavy 5/8 inch drywall onto the ceiling. To prevent sagging, I need to support the 2 by 4’s every four to five feet, by attaching them to the floor joists of the second floor.

That gets me back into the issue of noise, or to be more precise, impact transmission – dampening down the noise of footsteps. We tackled the same issue while finishing the basement.

To decouple the support for the drop ceiling from the floor joists, and thus reduce the impact transmission, I used a neoprene bushing with a neoprene washer followed by regular steel washers.


As you can see, the long screw, which is the transmission rod for any vibration from the floor joists, is not in direct contact with the drop ceiling framing. The neoprene bushing and washer keep it from direct contact with the 2 by 4, and so does the over-sized hole above the washers (3/8 inch hole for a 1/4 inch screw).

The soffit

I have one short section of six inch duct that is running along a short wall in the living room. Rather than building another drop ceiling for the entire living room, we opted for a short and small soffit instead.

About Marcus de la fleur

Marcus is a Registered Landscape Architect with a horticultural degree from the School of Horticulture at the Royal Botanic Gardens, Kew, and a Masters in Landscape Architecture from the University of Sheffield, UK. He developed a landscape based sustainable pilot project at 168 Elm Ave. in 2002, and has expanded his skill set to building science. Starting in 2009, Marcus applied the newly acquired expertise to the deep energy retrofit of his 100+ year old home in Chicago.

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