I want to run a 7 inch duct between two ceiling joists (parallel to them), 10 feet across an entire room (wall to wall), so I can replace a failing ductless range hood with a ducted one.
The house is 1896 construction and there are diagonal braces everywhere. Here is a picture of how the bracing was done, taken from above:
It's a 10 foot run, there are probably at least two such braces in the joist bay I want to use, but I won't know til I open it. The joists are 2x9 actual (not nominal).
Can I remove the braces, install a 7" duct in the 9" bay, and then put a few 2" blocks beneath the duct? Or do I even need the blocks?
Let's assume that in one or two other places above my kitchen, the braces have already been removed for previous projects. I should not assume my joist bay will be the only one with original bracing removed. This photo is not from above my kitchen, it's above a different room but as you can see in THAT case, bracing was removed for a 4" waste pipe. I MUST assume such things have been done above the kitchen during many major renovations over the decades. If I add blocks they will be on the bottom (drywall) side of the joist, while the top will be braced by the wood subfloor above.
The answer to this similar question suggests that if blocking was there originally, cutting holes in it is preferable to removing it. I'm adapting that here, suggesting adding partial blocking to replace bracing. But it's not the same era of construction.
