Thanks---we do have a plaster wall with wood lathe, so you think that might be a feasible option? The hood is 46 pounds, so I'm not sure if that's considered heavy or not....

You can cut a piece of plywood (like 3/4" thick) and mount it on the wall to span the studs, then use that to mount the hood to. It will cause the hood to stick out that much further from the wall, so that might mess with your clearances.

About mounting to the lath, depends on what you have.

Now it your lath is like what we had upstairs, darn stuff was 3/4" by about 4" wide, with groves milled in to hold the plaster - and firmly attached with larger nails - even with a big pry bar that stuff held firm - and hard - wore out blades trying to cut through it. You could mount just about anything to that.

Most of the house had the standard 1/4" thick by 1" wide lath strips - the kind you can break across your leg with minimal effort. Held on by 1" wire nails - very easy to pop off the walls. (they make wonderful fire starter- but mine are also 75+ years old).

I saw lots of evidences where previous owners had mounting things to the walls. Sometimes the screw hole would be about 1/8" from the edge and the lath was split, sometimes they used a bit too much force and stripped out the threads that formed in the lath. From what I saw, I'd have no confidence using the lath for support other than to hang small pictures.

if you go that route, you need to put in toggle bolts, not screw it to the lath. It could cause flex in the wall, and over time the plaster may crack. If you plan on tiling your backsplash, any flexing will could also pop off the tiles.

For me, I'd be cussing, but I'd be finding a way into the wall (either front or back side, which ever is easier. Though with plaster that is a total pain, sheet rock is easy. Otherwise I'd be paranoid the fan it going to end up through my cooktop.

We never mounted a fan to the wall, but we did have an OTR range that mounted to the wall and the upper cabinet.

BTW - a good way to put in supports is to make a box out of 2x4's and then insert the box in between the studs, and attache the "sides" to the studs. No toe nailing needed, so you won't split the ends of the 2x4's. We had a lot of places we had to frame up using that method as we didn't want to open the wall up any farther than needed (just center line of the studs.

Here is what I would try to do. You'll have to see if this will work with your hood's mounting points.

Get a strip of steel, 1/8'' or 1/16'' thick and at least 2'' wide, long enough to reach across two studs behind the hood. Drill holes through the strip that will line up with the hood's mount points. Place bolts through the holes, secure them with nuts, leave enough bolt length to go through the hood's mount points. Use the thinnest nuts you can find. Go to a hardware store where you can pick out and try the bolts/nuts and buy just the two or four that you will need. Tighten these nuts very well; even better, put Loctite on the threads first.

Drill holes at the appropriate points on the strip and use long screws or lag bolts to mount the strip to the wall, with the extra length on the hood mounting bolts facing out. Drill shallow depressions in the plaster where the heads of the hood mounting bolts will be, so that the strip will sit flush on the wall. Now you have the hood mounting bolts protruding from the wall. You can mount the hood on those bolts. The thickness of the steel strip and the nut on the hood mounting bolt should only be about 1/4'', so the hood will only be ''spaced out'' from the wall by that amount. This works because, why the steel strip can be flexed in one dimension when it is just loose, once it is screwed to the wall, it can't flex in that dimension - and a 1/16'' steel strip is pretty stiff in the other two dimensions, and pretty stiff against twisting too.

If the studs are quite far from the hood mounting points, you may want to use a wider steel strip or secure the strip to the wall by four bolts, two lower and two upper. You may be able to find such strips at the big box home improvement store.

Thanks John---this is a smart solution! Unfortunately we already did this the conventional way and hacked out a section of the wall---relatively painless though I still have to patch the plaster! But this is a great idea to keep in mind for other hanging-on-plaster tasks.

I like that idea too- would be much less obtrusive than a sheet of plywood. The bolts from the back side are the key.

I think you chose the best solution, by far it's the strongest and least likely to have any flexing.

we just intalled a TV on the wall. The "perfect" place was right in the middle between two studs, Dh just rolled his eyes and moved it over 8" to the stud. Visually, it's fine, just not exactly where I would have put it. He wanted it much lower too, but I won that part LOL!!

When we were planning the location of our cooktop/ range hood, the "perfect" place ended up under a ceiling joist. We have low ceiling so there was no room between the hood and the ceiling to angle the vent over, so I have 32" on one side and 27" on the other. We could have cut the joist and transfered the load to the adjacent ones, but decided it wasn't worth the trouble. Without a tape mearsure, you can't really tell - each side has a different door/drawer configuration anyway.