Framing Your House (cont. p. 14)

Making Joists and Ducts Work Together
 

Building a two-story house on a concrete slab may create an issue with heat & air duct work that you will need to resolve before framing begins.

It’s not a serious matter, just one that will take a little bit of advance planning.

If you are not placing the first-floor duct work under the slab, which is a more complicated and expensive option, then you must plan in advance how those ducts will be routed in relation to the joists supporting the second floor.

Your choice is to route the ducts through designed openings in open-web trusses or I-Joists, or to drop the duct work underneath 2x joists or conventional I-Joists. 

 

Dropping ducts below joists, as seen here, requires your framer to return after the rough-in of duct work to frame around the ducts, known as a “furdown” ceiling. This technique is fairly common among builders who are trying for the lowest possible price-per-square-foot.
A box is built around the duct work. You should plan this technique in consultation with your heat & air contractor to determine appropriate routing of ducts for your plan.
Here the duct work with furring runs around the perimeter of the room. The drywall finish creates the effect of a tray ceiling, which can be an attractive look that appears to be part of the original design.

 

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