The insert ARE 2K for something that works. Are you an actual woodworker? With tools.

" How difficult is the build? What are advantages to purchasing one already build … but expensive? "

It is a finished product akin to furniture. I personally would not attempt this without being capable and having the tolls required to build build custom cabintery and done it at least a few time over. Its a good way to turn $500 worth of furniture grade plywood into firewood in a hurry.

Thank you! Zumi the inserts are much less than $2000. I am looking for 36” vent hood … not something massive. I do have tools but would not attempt to build it … I am wondering if my GC could….
Millworkman ; there are quite few tutorials on how to build one… some using a drywall.

I think stainless steel is much more expensive than plywood and more difficult to cut. Yet there are 36” hoods (ex zline) which run $500-$800. The plywood hoods are not finished … you can get one primed but still you need to paint it. ….

Junk inserts might be less. But to get something capable, and sorta quiet, you need to be in the 1K+ category. It needs to be wider and deeper than your range. Plus, you need to add a make up air system.

Hi Minardi, what is a make up air system? My current vent is open to outside ( vents outside). The stove is 30” … I think that the 36” vent should be sufficient

Make-up air (MUA) is the air that has to flow into the house to make up for the air that is leaving the house. Steady state, no air leaves the house that doesn't get replaced. However, there are efficiency and safety issues that are of concern.

Safety. Combustion appliances that take air from the house interior (connected to the kitchen) will back-draft and allow carbon monoxide to enter the house if the house pressure is some small amount below the exterior pressure that the combustion appliance (and the hood) are connected to.

Efficiency. Hood system blowers have decreased flow rate in some proportion to the pressure difference across the blower. This difference is the sum of the MUA pressure loss and the loss across the hood baffles, transitions, ducting, etc.

Very weak and generally poorly functioning hoods are allowed by code to not have a deliberate MUA system if their blower's rated flow (hanging in free air) is under 400 CFM. (This varies with municipality.) Otherwise, either a passive (no blower) or active (blower controlled by some relevant measurement) MUA path is needed.

Thanks Kaseki! Oh … this is bit too much for my poor “I just want new kitchen cabinets brain” LOL … I will let the GC worry about. However I will check the installation instructions for the stainless steel vent hoods with 600 CFM to see what they require.

For MUA you will need to check with your local code enforcement officer.

MUA is code, whether or not the AHJ enforces it. It's for you and your family's safety, so you do not backdraft noxioius vapors into the home.

However, if your combustion appliances have their own MUA, such that they are connected to the outside or are in a sealed room with an outside opening, then the safety issue is likely met. (Approval is still the province of the code enforcement officer.) I have seen a modern gas furnace that used a concentric duct assembly to provide both intake and exhaust.

Even without a safety issue, how many CFM one actually can get from a given hood system will depend on how tight one's house it.