Running Ductwork Through Floor Trusses

Is that a towel in there.

Running ductwork through floor trusses. I understand that the maximum size hole i can put through a 9 floor joist is 3. You may be able to work with a wide shallow duct so you can have a broad not too deep soffit for the cross joist duct run. But if i add a 5 booster fan would it be possible to retain proper air flow and route this duct through the joist. In this case it s big enough that there s even a joist running right through the middle.

Just be sure to get the sizing sorted out correctly ie a 12x12 duct cannot be replaced by a 3x48 duct same area as there s a lot more friction in the 3x48 but the correction factors for duct shape are surely. I used a 6 hole saw to run a new duct into an addition we built. If you need to cut through a joist firm up the floor as shown in fig. Rather than try to run the flex duct through it which would have required at least another 2 i put a 1 long section of 6 rigid duct through the hole and attached the flex to both sides of it.

I am helping my sister in law build their house and they are using floor trusses 14 inch depth open web trusses at 19 2 oc. Run hvac duct through composite lumber beams. And wiring through a joist. 2 grade of douglas fir and maximum span floor joists imperial units.

But without proper support ducts can develops sags or kinks that reduce airflow 4a 4b. What the installer did here was to screw a piece of sheet metal to the bottom of the joists and attach a duct to it to carry the air back to the hvac system. To minimize problems with ductwork. Sometimes the best route for a flexible duct run is up and over an obstruction.

The rise of wood i joists has challenged scl manufacturers to come up with a safe practical ways to permit larger. Maximum floor joist span no. As we look closer here s what we see in this house. There is a nice rectangular ope area to run the hvac ductwork through in the middle of each truss.