OTR Microwave install (no studs!)

The installation manual states find a stud behind the wall to install the brackets, but after a 2 hr investigation, I determined that there are no studs behind the microwave!?!?

The microwave is 30" wide and not a single stud behind the walls, what the F is up with that!? Shouldn't studs be 16" off center?

What I did notice was the exhuast outlet runs 'down' and out the wall... and that the steel sheet metal encompasses that area behind the microwave.

Question is, can I drill this bracket into the sheet metal? is it sturdy enough as opposed to the studs?

I am confused...

Doesn't the bracket only help hold it against the wall and position it and the bulk of the weight is mounting it to the cupboard above? I would be worried about the cupboard coming down if you can't find an studs.

How did you determine there are no studs? Stud finder didn't register any? put a few test nails into the wall?

If you can't locate the studs, then measure from any light switches or outlets that are along the same wall.

in my house some walls have 2 layers drywall then the cheap studfinder wont be able to find anything.

If you have no studs use toggle bolts. You can pick them up at home depot

I drilled some holes in the drywall to confirm there are no studs behind the microwave. What's next?

I dont know if I feel safe with using togglebolts or hardcore wall anchors to hold up this microwave. As if it fell, I would be in some big trouble.

Also, the duct behind the microwave is not actually the circular duct, but a rectangular sheet metal duct... is this okay? I know the circular duct pulls air through and maintains pressure. This can't be the same for the big duct I currently have?

thanks for the help!

Quote:

---

Originally posted by bimmere92
I drilled some holes in the drywall to confirm there are no studs behind the microwave. What's next?

I dont know if I feel safe with using togglebolts or hardcore wall anchors to hold up this microwave. As if it fell, I would be in some big trouble.

Also, the duct behind the microwave is not actually the circular duct, but a rectangular sheet metal duct... is this okay? I know the circular duct pulls air through and maintains pressure. This can't be the same for the big duct I currently have?

thanks for the help!

---

Honestly I think it's a lot of worry about nothing. Good anchors, combined with the mount to the upper should have no issues. Neither should your duct.

I use wall anchors all the time, and I've used a bunch of different types over the years.

The best of the screw in style anchors are all metal. Stay away from the plastic ones. Of the full metal screw in anchors there are 2 types. The first is identified by it's blade type end, stay away from these as well. The one's that I find work the best are only available at Rona (as far as I've seen) and they look like this.

https://ontario.nedco.ca/medias/sys_...W+ZINC_320.jpg

If I remember correctly the sheer strength if force is applied straight down is roughly 50lbs, depending on drywall thickness. If you're able to get 6-8 anchors installed that gives you a 300-400lb capacity, more than enough for a microwave and some peace of mind.

Quote:

---

Originally posted by rx7_turbo2
I use wall anchors all the time, and I've used a bunch of different types over the years.

The best of the screw in style anchors are all metal. Stay away from the plastic ones. Of the full metal screw in anchors there are 2 types. The first is identified by it's blade type end, stay away from these as well. The one's that I find work the best are only available at Rona (as far as I've seen) and they look like this.

https://ontario.nedco.ca/medias/sys_...W+ZINC_320.jpg

If I remember correctly the sheer strength if force is applied straight down is roughly 50lbs, depending on drywall thickness. If you're able to get 6-8 anchors installed that gives you a 300-400lb capacity, more than enough for a microwave and some peace of mind.

---

I wouldnt use those anchors for an OTR microwave.

Use these instead.

http://2ndfloorliving.com/wp-content.../07/SPRING.gif

Also, while it is crucial to have good anchoring for the back bracket along the wall. A large amount of the weight is also being supported by cabinets above the microwave. So while it is good to have a stud to use on the back wall. You will probably be fine without one.

That said. I find it hard to believe that you have a 30 inch span without at least one stud.

I have a house from the 50s and could only find the edge stud, then possibly a 2x2 on the 16" center. I ended up having to make a plywood sheet that stretched the length of the wall behind the cabinets. I anchored the bracket to this.
Just watch out for your measurements on the top cabinet, they'll be out because of the plywood.

Good luck, major pain in the ass but mine was a floor model, no templates for installing and I also had to modify the electrical and the outlet because the house was 1950 something.

Basically, mine is a temporary job until I renovate the whole kitchen and pull back that wall.

I wouldn't use drywall anchors if the studs were further apart than 30 inches.

I'd rip off the drywall and figure out what's going on back there.

Quote:

---

Originally posted by sputnik


I wouldnt use those anchors for an OTR microwave.

Use these instead.

http://2ndfloorliving.com/wp-content.../07/SPRING.gif

Also, while it is crucial to have good anchoring for the back bracket along the wall. A large amount of the weight is also being supported by cabinets above the microwave. So while it is good to have a stud to use on the back wall. You will probably be fine without one.

That said. I find it hard to believe that you have a 30 inch span without at least one stud.

---

The screw in type wall anchors I suggested have equal sheer strength to toggle bolts of the same size, in drywall of the same thickness. That's a big misconception, believe me I've seen PLENTY of toggles pulled though walls because people think they can hold twice what they're actually rated for lol.

I've hung countless Mitsubishi evaporator units with the screw in anchors I suggested, and have for years now. never had an issue whatsoever.

Like I said use 6-8 anchors, screw in or toggle doesn't matter and you're not gonna have an issue.

Most OTR manufacturers only require that one of the mounting bracket attachment points are into a stud in the wall. If you can get two into studs, even better, but we mount these with toggle bolts all of the time, no issue.

The two (or more) bolts that attach the OTR to the underside of the cabinet box hold a lot of the weight of the unit on their own.

You will be fine if you only use the toggle bolts supplied with the OTR to mount the wall bracket.

Your exhaust outlet sounds pretty unconventional though. If it has an immediate 90 degree bend downward right off the OTR the fan is going to be completely useless... and noisy.

What kind of OTR is it anyway?

Quote:

---

Originally posted by rx7_turbo2


The screw in type wall anchors I suggested have equal sheer strength to toggle bolts of the same size, in drywall of the same thickness. That's a big misconception, believe me I've seen PLENTY of toggles pulled though walls because people think they can hold twice what they're actually rated for lol.

I've hung countless Mitsubishi evaporator units with the screw in anchors I suggested, and have for years now. never had an issue whatsoever.

Like I said use 6-8 anchors, screw in or toggle doesn't matter and you're not gonna have an issue.

---

Are you actually suggesting that the the anchor you posted has a higher shear strength than a toggle bolt?

I thinks there's a law of physics that states otherwise.

Quote:

---

Originally posted by Seth1968


Are you actually suggesting that the the anchor you posted has a higher shear strength than a toggle bolt?

I thinks there's a law of physics that states otherwise.

---

Reading isn't your strong suit is it? lol.

God everything on this forum needs to be a fight. Listen carefully. I'm saying the anchor I suggested has the SAME sheer strength as the toggle bolt you posted. Did you get that?

The anchors I posted have a 50lb sheer strength, 1/4 toggle bolts in 1/2" drywall have a 50lb sheer strength. Now a larger toggle bolt will have a larger sheer strength, but my point was that if the guy used 6-8 anchors of the type I suggested OR the toggle bolts you suggested then it would be enough for the microwave and some extra insurance.

The anchors I suggested are actually very impressive for what they are. If you read all my posts you would know that I was very specific with the anchors I suggested not all "zipit" style anchors are created equal. I have literally installed THOUSANDS of the anchors I suggested in order to secure countless items of various sizes and weights, and have yet to have an issue with them whatsoever.

I'm guessing you won't read any of that though so go ahead and tell me all about physics please lol.

I didn't suggest any anchor, nor did I say the anchors you suggested wouldn't work.

My error was also considering horizontal strength, in which case a toggle has much more strength.

Quote:

---

Originally posted by Seth1968
I didn't suggest any anchor, nor did I say the anchors you suggested wouldn't work.

My error was also considering horizontal strength, in which case a toggle has much more strength.

---

Fair enough.

Toggles or the one's I suggested, there's more than one way to skin a cat, or in this case install a microwave.

Quote:

---

Originally posted by masoncgy
Most OTR manufacturers only require that one of the mounting bracket attachment points are into a stud in the wall. If you can get two into studs, even better, but we mount these with toggle bolts all of the time, no issue.

The two (or more) bolts that attach the OTR to the underside of the cabinet box hold a lot of the weight of the unit on their own.

You will be fine if you only use the toggle bolts supplied with the OTR to mount the wall bracket.

Your exhaust outlet sounds pretty unconventional though. If it has an immediate 90 degree bend downward right off the OTR the fan is going to be completely useless... and noisy.

What kind of OTR is it anyway?

---

The OTR is a Samsung SMH9207ST I believe... its pretty heavy thus the concern.

It came with toggle bolts but stated the bracket should be connected to atleast one stud. Also, the top cabinet is not mounted to a stud (since no studs behind the wall)... so not sure how much that will support.

I am just scared of it falling... and then I have a microwave and oven that needs repair!

Quote:

---

Originally posted by bimmere92

Also, the top cabinet is not mounted to a stud (since no studs behind the wall)... so not sure how much that will support.

---

That changes everything. IMO, I would not mount it with no studs on either the vertical or horizontal support. I would remove the down venting from behind the wall, and add in 2x4 cross members. That means of course, you'll be venting the conventional vertical way.

Other than that, do the cross member idea behind the cabinet, and vent from the back. The main problem with this, is you're depending on the strength of the cabinet's bottom shelf.

Quote:

---

Originally posted by bimmere92



The OTR is a Samsung SMH9207ST I believe... its pretty heavy thus the concern.

It came with toggle bolts but stated the bracket should be connected to atleast one stud. Also, the top cabinet is not mounted to a stud (since no studs behind the wall)... so not sure how much that will support.

I am just scared of it falling... and then I have a microwave and oven that needs repair!

---

The Samsung 9207 is a big OTR, but it's no larger or heavier than what Panasonic or Whirlpool puts on the market, so no issue with extra weight and what not.

This sounds like a real strange set up. You have a 30" span, there has to be at least one stud back there somewhere. How old of a house is this?

That upper cabinet box is just screwed into the neighboring boxes and not into the wall? Wow. How has that not fallen down with the weight of goods put it in... or at least be sagging down?

The downward exhaust venting concerns me too. Completely unconventional, basically useless actually. You might as well just re-circulate the air with a charcoal filter as the back pressure that 90 degree bend will create will make noise and virtually eliminate the fan's ability to move air.

Put some pics up of the wall, cabinet box, etc. Let's have a look.