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TheMole

join:2001-12-06
USA

How much weight can a standard stud wall hold?

I've recently moved into a home built in 1986.

I have a 150lbs plasma TV that I previously had wall mounted with an Omni mount (»www.newegg.com/Product/Product.a···82798001) in my old home. The old home was a townhouse built in 2003. The TV was mounted and pushed back almost all the way to the wall -- it stuck out maybe 8-10 inches from the wall.

In my new home, the spot for the TV is rather awkward and I need to have the TV stick out from a small alcove approx 25 inches and then angled to the left.

I purchased a new mount for the TV (Premier Mounts AM300 UPC 829973150839).

When the installer came (licensed contractor) he told me that it would be unwise to mount the 150lbs plasma on the wall with an arm that extends 25 inches. he said he would worry the wall would not support it.

so i decided to buy a new, lighter TV... (...fast forward, i bought at 55lbs LED tv and have to send it back, and am now looking at a 85lbs plasma TV).

The instructions on the Premier Mounts AM300 state that the wall must hold 4x the weight of the TV. The mount itself weights 60lbs.

So, (85x4)+60= 400 lbs load.

Can an interior wall, with studs 16 inches on center hold 400 lbs of weight from a TV mount?
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(1) It's either 99¢ or $0.99; not .99¢ (2) It's "so MUCH fun" not "so fun"



cowboyro
Premium
join:2000-10-11
Shelton, CT
Reviews:
·AT&T U-Verse

It all depends if and how the sheathing and drywall are anchored to it and how lousy the framing was done.
I would assume you anchor the mount to 2 studs, not just 1. It should hold without any issue. I'd be more worried about the screws holding in crappy wood.
Also you are incorrectly assuming a 400lb of weight. It's 400lb of pull from the top screws.



AVD
Respice, Adspice, Prospice
Premium
join:2003-02-06
Onion, NJ
kudos:1

1 recommendation

you have to mount directly to the studs
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--Standard disclaimers apply.--



TheMole

join:2001-12-06
USA
reply to cowboyro

said by cowboyro:

It all depends if and how the sheathing and drywall are anchored to it and how lousy the framing was done.
I would assume you anchor the mount to 2 studs, not just 1. It should hold without any issue. I'd be more worried about the screws holding in crappy wood.
Also you are incorrectly assuming a 400lb of weight. It's 400lb

4 lag bolts, mounted to two studs (two bolts per stud), studs are 16 inches on center and we're using studs immediately next to each other.

yes - i agree, i'm concerned the bolts will not hold to the studs, too.

said by cowboyro:

Also you are incorrectly assuming a 400lb of weight. It's 400lb of pull from the top screws.

right you are -- it's 400lbs of pull from the top. total weight is 145 (85+60).
--
(1) It's either 99¢ or $0.99; not .99¢ (2) It's "so MUCH fun" not "so fun"


TheMole

join:2001-12-06
USA
reply to AVD

said by AVD:

you have to mount directly to the studs

the mount is connected to two studs, with four lag bolts.
--
(1) It's either 99¢ or $0.99; not .99¢ (2) It's "so MUCH fun" not "so fun"


AVD
Respice, Adspice, Prospice
Premium
join:2003-02-06
Onion, NJ
kudos:1

are they wood studs?
interior or exterior wall?
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--Standard disclaimers apply.--



cowboyro
Premium
join:2000-10-11
Shelton, CT
Reviews:
·AT&T U-Verse
reply to cowboyro

Looks like a 3/8" lag bolt going 2" deep has a pull force of 1900lbs.
Go 1/2" at 3.5" deep and you have a pull force of 3500lbs.
Should be fine
Now if you keep moving the arm that may be a different story...



TheMole

join:2001-12-06
USA
reply to AVD

said by AVD:

are they wood studs?
interior or exterior wall?

wood studs, interior wall. wall is load-bearing, i believe.
--
(1) It's either 99¢ or $0.99; not .99¢ (2) It's "so MUCH fun" not "so fun"


TheMole

join:2001-12-06
USA
reply to cowboyro

said by cowboyro:

Looks like a 3/8" lag bolt going 2" deep has a pull force of 1900lbs.
Go 1/2" at 3.5" deep and you have a pull force of 3500lbs.
Should be fine
Now if you keep moving the arm that may be a different story...

EXCELLENT. this is what i was looking for and hoping for. Thanks. The bolts are exactly: 5/16 x 3 Lag Bolts -- smaller than your spec, but probably effective. (i needed the key word "pull force" from your post... perfect. Here is a good URL on this: »www.kineticsnoise.com/SeismicBoo···rews.pdf

The arm will only be moved occasionally. To watch TV, I have to have the arm extended -- I watch a lot of TV -- so it'll likely always be in the same spot.

I'll push the TV back to the wall when i have formal gatherings at my house - where I care that the TV set up looks neat and not like a movie theater..
--
(1) It's either 99¢ or $0.99; not .99¢ (2) It's "so MUCH fun" not "so fun"


alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1

1 edit
reply to TheMole

Do they make wall mount that can anchor on 3 studs? Anyway, I doubt you'll have much issues. They make wall mounts that can hold 250lbs, so if they follow the same rules, it would require studs capable of holding up 1000LBS!!!

2x6 can easily hold 400lbs if they were properly achored top and bottom, I think 2x4s can do it as well, but not much more. I have been framing my basement all month and when I make sure they are secured, I give them a good hard pull, I'm 215lbs.

The 400lbs load is probably because of the lever effect caused by the distance of the TV from where it is anchored.

Get the longest bolts possible with the wides threads so that they dig in deep into the studs and grip tight. Make sure the two top bolts share an even load as they'll carry most of it.

Of course, if someone gets behind the TV and pushes down on the arm, I doubt the bolts will hold much more force.



TheMole

join:2001-12-06
USA

said by alkizmo:

Do they make wall mount that can anchor on 3 studs? Anyway, I doubt you'll have much issues. They make wall mounts that can hold 250lbs, so if they follow the same rules, it would require studs capable of holding up 1000LBS!!!

the mount is designed to hold a TV up to 300lbs. The TV i plan to have here is 85lbs. My concern really is ensuring the wall will hold up to the specs of the mount after the installer told me not to hang the 145lb. TV.

said by alkizmo:

Of course, if someone gets behind the TV and pushes down on the arm, I doubt the bolts will hold much more force.

I hope that never happens -- the TV is tucked well away
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(1) It's either 99¢ or $0.99; not .99¢ (2) It's "so MUCH fun" not "so fun"


alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1

said by TheMole:

said by alkizmo:

Of course, if someone gets behind the TV and pushes down on the arm, I doubt the bolts will hold much more force.

I hope that never happens -- the TV is tucked well away

Kids kids kids. They are evil and can sneak in tight places to cause damage.

My son tried to get behind my flat screen to recover a NERF dart. Let's just say I caught the TV just in time.


LazMan
Premium
join:2003-03-26
canada

1 recommendation

reply to TheMole

To answer your question:

2x4x8' #2 SPF "stud-grade" is good for about 3000# of compressive load...

But that's not what you're actually worried about...

What I did when I mounted my 55" LCD, was removed the drywall behind the TV, and replaced with 1/2" g1s plywood, spanning 4 studs... Then I installed the mount to the centre 2 studs using 3 1/2" x 3/8" lag bolts. 3/8" lag screw has a shear rating over 300# - so 4 of them can hold well over 1000# with no issues.

Painted the plywood to match the wall, and it was covered by the TV anyways... Probably overkill, but I wasn't concerned with it coming down, ever...



alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1

said by LazMan:

What I did when I mounted my 55" LCD, was removed the drywall behind the TV, and replaced with 1/2" g1s plywood, spanning 4 studs... Then I installed the mount to the centre 2 studs using 3 1/2" x 3/8" lag bolts. 3/8" lag screw has a shear rating over 300# - so 4 of them can hold well over 1000# with no issues.

I can imagine if for X reason the wall mount couldn't be aligned to anchor on the studs, that a plywood board would give flexibility in terms of location.

However, I don't see how 1/2" plywood can add strenght if you were going to put the lag bolts through the studs anyway. In fact, you may have lost strenght because the lag bolts didn't go as deep in the studs as they would have without the 1/2 plywood in the way. I'd imagine that a bolt 3 1/2" deep (through and through) into the 2x4 studs is stronger than 3" in the stud + 1/2" in the plywood.

Correct me if I am wrong.


LazMan
Premium
join:2003-03-26
canada
reply to TheMole

The plywood add lateral strength to the 2x4 studs...

Pull-out strength on a 3/8" lag bolt is about 200 lbs per inch, so anything more then 2" of thread into the stud, you'll shear the bolt before you'll pull it out. The 3 1/2" bolts I used were overkill.

Just how I did it, and it worked out very well for me...



alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1

said by LazMan:

The plywood add lateral strength to the 2x4 studs...

Pull-out strength on a 3/8" lag bolt is about 200 lbs per inch, so anything more then 2" of thread into the stud, you'll shear the bolt before you'll pull it out. The 3 1/2" bolts I used were overkill.

Just how I did it, and it worked out very well for me...

That's assuming that the physical studs themselves could crack under the weight before the bolts pull out, thus distributing the weight over 4 studs.

But I'd be more inclined to assume that if the wood grain of the stud can hold a grip on the bolt threads, then stud as a whole hold the same force structurally.


AVD
Respice, Adspice, Prospice
Premium
join:2003-02-06
Onion, NJ
kudos:1

flexure vs, shear


Bob4
Account deleted

join:2012-07-22
New Jersey
reply to alkizmo

Won't the stud bow-out over time?


AndrewG2

join:2006-01-20
Niagara Falls, ON
reply to TheMole

Yah, I'd go with a chunk of plywood to spread the load over as many studs as possible. What I'd be worried about is not the straight up and down load, but the torsion effect on the stud if you moved the TV side to side much. Also, I'd like to use smaller fasteners in more places on the stud, rather than one huge one, which if you drill it slightly off is basically cutting the stud in half.

Probably overkill, but when I put up a shelf, you could sleep on it.



alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1

Well you guys convinced me that plywood boards can help and that tip will come in handy.

While I'm finishing my basement, I have a prime location for my theater room. I was planning to hang it on a wall as well, but I don't mind losing a few inches more by covering that wall in plywood. It's only a 10 feet long section with two perpenticular walls on the sides, so it won't show, especially with the gyprock on top.


kherr
Premium
join:2000-09-04
Collinsville, IL

If your going to open the wall to install plywood, why not just have a bracket made and bolt it to the studs instead of lags ...



djrobx
Premium
join:2000-05-31
Valencia, CA
kudos:2
Reviews:
·Time Warner Cable
·VOIPO
reply to TheMole

I had a 100lb 50" plasma mounted to a Peerless arm - nearly fully extended (about 20") and turned 90 degrees. It basically sat in that position from 2002-2009. There were 6 bolts and it spanned two studs. I did not use any additional plywood.

When I removed it after 7 years, there were no signs of bowing or any other trouble. There were no "stress fractures" in the drywall anywhere. The home was built in 1998.
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AVD
Respice, Adspice, Prospice
Premium
join:2003-02-06
Onion, NJ
kudos:1
reply to kherr

said by kherr:

If your going to open the wall to install plywood, why not just have a bracket made and bolt it to the studs instead of lags ...

why behind the wall, on the exterior of the wall behind the TV. You can stain it and put some molding around it to look nice if it is a swivel arm.
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--Standard disclaimers apply.--


alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1
reply to kherr

said by kherr:

If your going to open the wall to install plywood, why not just have a bracket made and bolt it to the studs instead of lags ...

I dont understand, neither do I understand AVD.

Btw I'm not opening the wall to put plywood. The wall is already bare. Studs only.


The E
Please allow me to retort
Premium
join:2002-05-26
Burnaby, BC
reply to TheMole

Oh Lordy! You guys are going WAY over the top on this.

4 lags securely screwed into any halfway decently framed 2x wood stud wall will support a monster TV up to 200lbs, on an extension, plus you could hang from it as well.

The only concern is the rating of the mount, and that has everything to do with the materials used to build the mount, not the wall it's being attached to.

That installer either didn't know his shit, or didn't want to do the job. (Assuming you haven't left out any pertinent details)
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"All opinions stated by me are solely my views and do not reflect the views of my employer, this site, or even myself depending on my level of sanity at the moment"


AndrewG2

join:2006-01-20
Niagara Falls, ON
reply to alkizmo

You're in a lot better position just to hang it on the studs then. You can assure that the studs are sound A grade stuff that aren't missing corners and have more than one nail holding them in...

I advise the paranoid approach more for when you don't have a clue what is in your wall, and Murphy's law will have you finding the weak bit.



Draiman
Let me see those devil horns in the sky

join:2012-06-01
Kill Devil Hills, NC
reply to TheMole

I know two normal 2x4 studs with 1-2 lags in each stud for a flush TV mount can hold a 65-80 pound TV plus 200-225 from someone hanging on it.



AVD
Respice, Adspice, Prospice
Premium
join:2003-02-06
Onion, NJ
kudos:1

said by Draiman:

I know two normal 2x4 studs with 1-2 lags in each stud for a flush TV mount can hold a 65-80 pound TV plus 200-225 from someone hanging on it.

needs pics
(preferably video)
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--Standard disclaimers apply.--


alkizmo

join:2007-06-25
Pierrefonds, QC
kudos:1
reply to AndrewG2

said by AndrewG2:

You're in a lot better position just to hang it on the studs then. You can assure that the studs are sound A grade stuff that aren't missing corners and have more than one nail holding them in...

Well, they are load bearing studs from the original construction of the house. Though they are only 2x4 (not major load bearing studs). I'm actually not sure if I should risk drilling those studs and weaken their structural integrity. Heck I'm not even sure if I'll even put a mount. Currently my big screen TV is on a very nice set of furniture with useful cabinets underneath.


Draiman
Let me see those devil horns in the sky

join:2012-06-01
Kill Devil Hills, NC
Reviews:
·Verizon FiOS
reply to AVD

said by AVD:

said by Draiman:

I know two normal 2x4 studs with 1-2 lags in each stud for a flush TV mount can hold a 65-80 pound TV plus 200-225 from someone hanging on it.

needs pics
(preferably video)

If it was uncommon or rare sure. Being as common as a person with 10 toes it really doesn't warrant the time/energy to document it though. If I get bored this week-end I'll pop a lag into my new garage stud and try to stand on it. I'm willing to bet a single lag will hold 200 pounds easy.
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