I believe I'm just paranoid about hanging an expensive TV... I've done a lot of searching and haven't found anything that applies to my specific situation.

We own a older home... built circa 1925-1932 (varying records). The previous owner laminated the walls in the living room with 3/8" drywall/sheetrock. This means we have wood lathe + plaster, which adds up to almost 1" in thickness, plus the 3/8" thick drywall.

I have a Panasonic TH-50PZ80U coming tomorrow and I have a Monoprice 3900 wall mount. TV weighs ~84lbs, while the mount is rated for up to 165lbs. It appears that the TV, conveniently enough, will end up between two studs. What I'm trying to decide is:

A. Just install the mount as it commonly would be with provided hardware, right over the drywall, with four lag screws into two studs.

B. Install the mount the same way, but use 1" longer lag screws.

C. Cut out a section of drywall and plaster and install a piece of plywood.

Option C is obviously the safest bet, but requires the most prep and effort. Plus it's cold out and most of my wood working tools are outside. It also seems unnecessary given that I can hit two studs and do so very evenly.

The main thing that brought this doubt on was something printed in the instructions. "Forbidden Instruction: Do not mount onto plasterboard or paneled walls." I'm sure that simply means that you should not install the mount purely using anchors. I'm honestly more concerned about torquing the lag bolts properly so that they're snug but not to the point that I weaken them and possibly fracture them.

Any thoughts?

Thanks!

Use option B and don't worry.

Hi!
I do this for a living, and as a result, have hung hundreds of displays.
Anyway, what I do, is throw away the lag bolts that come with the mounts, which are cheap grade 3 hardware. I replace them with the next size larger (diameter) , grade 5 bolts, which are also at least an inch or so longer.

Do this, and make sure you get 4 bolts in the center of 2 studs, and you can hang a small motorcycle from the wall if you wish! Believe me, I know this for a fact!

Good luck!

....
We own a older home... built circa 1925-1932 .....!
glennt....what are the centers of the studs in your 1925 home? i've been concerned in my late 1940 abode, that the stud spacing won't work with the tv mounts... thanks.


fitero.... it's nice that someone who actually knows what they are doing is willing to share their knowledge....thanks



TVbc

They're 16" on center. That hasn't been a concern of mine, although I don't know what type of wood the studs are. The monoprice mount instructions do keep saying "hard wood", but it doesn't say "hardwood". I'm just assuming the manual was translated from some overseas language.

Monoprice has confirmed that the mount simply must be attached to wood studs, regardless of whether said studs are covered in plaster, plasterboard (i.e. drywall; sheetrock) or paneling.

Thanks for the responses. I am going to pick up some longer bolts and call it good. Now the trick will be precisely locating the studs through those layers of drywall, plaster and wood lathe. I've done it before though!

.......The main thing that brought this doubt on was something printed in the instructions. "Forbidden Instruction: Do not mount onto plasterboard or paneled walls." I'm sure that simply means that you should not install the mount purely using anchors. I'm honestly more concerned about torquing the lag bolts properly so that they're snug but not to the point that I weaken them and possibly fracture them.

Any thoughts?

Thanks!

I also do this kind of thing all the time and here are a few more suggestions. The others posters are correct. Go with your option B, use larger diameter (at least 1/4 or 5/16 hex head lag bolts). You can find the studs using a stud finder, but it needs to be of the type that can scan through thicker walls such as yours (I have a Zircon Multiscanner i700). If you do not have a scanner,drop down to an area on the wall that is not as visible. You can drill a series of small holes to try and locate the firm wood (studs) Typically a 1/8 drill bit works fine. If there is no stud where you drill, the bit will pop all the way in when you drill past the lathe. If there is a stud, it will seem firm, even past the drywall/lathe and plaster. This is typically around 1 1/2 inches of thickness. You can narrow down exactly where the edges of the studs are with a series of holes. Once you have located the centers of the studs, then you can use a level to draw a plumb line up to where you want to drill the holes for the lag bolts.
You can now fill in all you exploration holes with some spackle or drywall compound. Sand smooth and paint.

Now, as for the holes to mount the bracket, the key is drilling the holes the right size for the lag bolts. I like to drill mine the same size as the minor diameter of the thread. This is the diameter if you were to measure in the groove of the bolt. For example, if the bolt is a 1/4", the minor diameter would be around 5/32".

Finally, to make the installation easier, rub the lag bolts across a bar of soap a couple of times. This will act as a lubricant making the installation easier. I would not worry about over torque. Simply screw the bolts in until the contact the bracket. Turn another 1/4 to 1/2 or so to make sure the bolts are snug to the bracket.

Let us know how it goes.

Rich

Thanks for the added tips. I'm particularly glad you added the bit about pre-drilling, as I've been debating on what size drill bit to use. I bought 4 5/16" x 4" lags at Home Depot; the same diameter as what was included with the mount, but 1/2" longer. I almost bought 4.5" lag screws, but that seemed excessive. If people can use the "stock" lags with drywall or plaster, the extra 1/2" makes up for more than the 3/8" of drywall OR most of the plaster, putting the amount of screw in the studs about where it would be "stock".

I already have a Zircon deep scan stud finder (plus AC scan). I picked one up since the old fashioned stud finder (i.e. "tapping with your knuckle") doesn't work to well on these walls. The Zircon still struggles, but it gets me close enough to start searching with small nails.

Also, I'm installing a Recessed Power Pro kit from Monoprice, so I will have holes to further aid in locating the studs. Cut hole, measure, and, bingo, studs located.

I'm actually a very confident handyman, having done considerably remodeling to homes now and in the past. There's just something about hanging a $1299 piece of glass on the wall that gives one doubt. Ya know? But, like someone said some where on here... smaller screws hold up your kitchen cabinetry, and that hasn't fallen off yet.

Thanks again!

Just found this thread, whew. Let's hope I can get my question answer here. I have a 42" Plasma coming(Panasonic Viera TH42PX80U). The wall that I'm going to mount it on (with Monoprice 3724 bracket), instead of having two equally spaced studs between the window, has 3 equally spaced studs(grrrrr). So, what are my options? Will mounting the bracket on the middle stud be enough? The TV is about 57 lb.

I have also read that some put in a 3/4" plywood, then mount the bracket on this. Anyone has pic of this? Thank you all.

This is a great forums with great people!!

Just found this thread, whew. Let's hope I can get my question answer here. I have a 42" Plasma coming(Panasonic Viera TH42PX80U). The wall that I'm going to mount it on (with Monoprice 3724 bracket), instead of having two equally spaced studs between the window, has 3 equally spaced studs(grrrrr). So, what are my options? Will mounting the bracket on the middle stud be enough? The TV is about 57 lb.

I have also read that some put in a 3/4" plywood, then mount the bracket on this. Anyone has pic of this? Thank you all.

This is a great forums with great people!!

Another option would be to run a couple 2x4's and attach to the 3 studs and then attach the mount to the 2x4's. with a little bit of effort, creativity and paint it could be hardly noticeable.

I have thought about that, but that's gonna stick out (to the side and out from the wall) quite a bit. I'll have to wait until the TV gets here.

I have thought about that, but that's gonna stick out (to the side and out from the wall) quite a bit. I'll have to wait until the TV gets here.

Seems you should be able to find two studs that don't stick out beyond the sides of a 50" plasma and to finish it off, you can box the 2x4's in with 1/2" plaster board on top and some finish lumber around the edges and then just sand and smooth and top with the wall color paint. Should only leave you about 1 3/4" out from the wall. Nobody should really be looking behind there so it doesn't have to be the most professional looking job.

I see that model is an articulating mount, but you should have some horizontal flexibility with where you hang the TV on the mount. Can you install the mount a few inches left or right, just far enough to catch a second stud? That mount is 32" wide, so if, for example, the middle stud was directly in the center, you would only have to install it an inch or two left or right to hit the next stud. Then, hang your TV an inch over in the opposite direction on the mount.

Otherwise, I would cut out a section of wallboard (drywall or plaster) slightly smaller than the height of the mount but 3/4" over the adjacent studs. Install sections of 2x4 lumber horizontally where the bolt holes on the mount line up and attach those 2x4s to the existing studs. Tuck these pieces in slightly behind your wallboard to support the wallboard, but try to get the center of these boards to line up with the center of the bolt holes in the mount. I'd probably consider short vertical pieces attached to the outer studs and two the horizontal boards for a stronger connection to the studs. This would have the added benefit of not having to cut out wallboard over the studs; just cut the hole to the edge of the stud. Faster and stronger.

For extra strength, cut out a piece of plywood to the size of hole, using the same thickness as your wall board. Attach that plywood to all three studs and to the new 2x4s. Also, I would recommend using drywall screws to attach the wallboard around the perimeter of the hole to the new 2x4s. A small amount of joint compound, sanding and paint should clean up the areas not cover by the mount.

Hopefully that wasn't too confusing.

*If* the middle stud really is dead center, I'd be tempted to simply cut two small holes next to each adjacent stud so I could slip a 2x4 in on each side. That is, if that is enough to make it so you can attach to the center stud, plus the new wood on each end, giving you 6 attachment points.

Another option is to simply get a 3 stud mount... i.e. a wider mount.

As an update to my own project...

Finding the studs was a bear. Worse than I remember. Besides the drywall and plaster, there's a staircase behind this wall. Anytime I got anywhere near the stairs, the stud finder got "lost. It was basically useless, other than a general idea of where studs might be. I guess the added rigidity throws off the echo it uses.

I installed the Recessed Power Pro kit first and measured to the left and right, and that got me where I needed to be. A series of holes with nails confirmed the location of the studs. Fortunately, I got a "best case scenario", with two studs almost smack dab in the center of the TV location.

I started out with a 7/32" drill bit for the pilot holes for my 5/16" lag screws. Based on this link: http://www.mcfeelys.com/category.aspx?cat=lag-stainless-steel&s_kwcid=stainless%20steel%20lag%20bolts|939219301 from this thread: http://www.avsforum.com/avs-vb/showthread.php?t=1016143

That seemed pretty snug for my studs, so I jumped up to a 1/4" bit. I've broken bolts before, so I have *some* feel for what is too much resistance. With my test hole, that still seemed tight. The others went in easier, but with a satisfactory amount of resistance (i.e. bite). My only concern was that my drill bit was 1/2" too short, but I don't think it was significant enough for the bolts to wedge the hole open and compromise the bite from the rest of the screw.

I didn't get a chance to take pictures of the mount of the power kit, but both installed beautifully. The power kit is awesome. I just hope the position works out, as I had nothing to reference from (i.e. the new TV). The only "issue" is that the drywall and plaster takes up a considerable amount of the low voltage openings, but not bad enough that I felt compelled to clearance the opening. Otherwise, my only problem was getting the old work electrical boxes installed, as they didn't accommodate that wall thickness (which, BTW, is closer to 1 1/8" - 1 1/4").

For those not familiar with what I'm talking about:
http://www.monoprice.com/products/product.asp?c_id=104&cp_id=10425&cs_id=1042505&p_id=4652&seq=1&format=2

Whew, I had to read that 3 times and I'm still confuse :-) I think I'll have a better on your suggestion to mount it off to the side. Hope that works.

I was looking for 3 studs mount that's articulate, but found none at monoprice. Oh yeah, the middle is dead center!!

Thank for everyone's suggestion, you have been very helpful. Guess I'll be busy this weekend, in a good way :-)

I see that model is an articulating mount, but you should have some horizontal flexibility with where you hang the TV on the mount. Can you install the mount a few inches left or right, just far enough to catch a second stud? That mount is 32" wide, so if, for example, the middle stud was directly in the center, you would only have to install it an inch or two left or right to hit the next stud. Then, hang your TV an inch over in the opposite direction on the mount.

Otherwise, I would cut out a section of wallboard (drywall or plaster) slightly smaller than the height of the mount but 3/4" over the adjacent studs. Install sections of 2x4 lumber horizontally where the bolt holes on the mount line up and attach those 2x4s to the existing studs. Tuck these pieces in slightly behind your wallboard to support the wallboard, but try to get the center of these boards to line up with the center of the bolt holes in the mount. I'd probably consider short vertical pieces attached to the outer studs and two the horizontal boards for a stronger connection to the studs. This would have the added benefit of not having to cut out wallboard over the studs; just cut the hole to the edge of the stud. Faster and stronger.

For extra strength, cut out a piece of plywood to the size of hole, using the same thickness as your wall board. Attach that plywood to all three studs and to the new 2x4s. Also, I would recommend using drywall screws to attach the wallboard around the perimeter of the hole to the new 2x4s. A small amount of joint compound, sanding and paint should clean up the areas not cover by the mount.

Hopefully that wasn't too confusing.

*If* the middle stud really is dead center, I'd be tempted to simply cut two small holes next to each adjacent stud so I could slip a 2x4 in on each side. That is, if that is enough to make it so you can attach to the center stud, plus the new wood on each end, giving you 6 attachment points.

Another option is to simply get a 3 stud mount... i.e. a wider mount.

Another, and probably final, update. The TV was delivered and the guys helped me lift it up onto the wall mount. Even though I was starting to expect the TV to look huge, it still looks far bigger than in the stores. At any rate, it looks and feels very secure. Confidently secure.

Worth noting, I felt compelled to check the lag screws for tightness last night, approx 24 hours after the initial install. They were still tight, but not quite as tight as the day before. I gave each screw another 1/4 to 1/2 turn while tugging on the mount.

I also had some trouble pulling cables through the low voltage wiring side of the power kit. I couldn't find any conduit that I could adapt to the kit at Home Depot, so there is none. And I couldn't get my fish tape to exit the bottom hole. I ended up using some string and a paper clip, with a folded fridge magnet in the bottom hole to attract the paper clip. Worked beautifully. I sensed that I needed to be VERY careful to push the wad of cables up into the bottom hole while I pulled the string out of the top hole. In the end, I had to remove the plate in the top hole and feed the cables through the plate by hand, but got the job done.

Another, and probably final, update. The TV was delivered and the guys helped me lift it up onto the wall mount. Even though I was starting to expect the TV to look huge, it still looks far bigger than in the stores. At any rate, it looks and feels very secure. .

Reminds me when I went form a 31" Mitsubishi CRT to a 51" Pioneer Elite RPTV. In the store the 51" didn't seem all that big but when the delivery guys brought it up into the house and put it in the room, I'm glad I didn't get anything bigger as those RPTV's were monsters compared to today's TV's.:D

Glad things went smoothly for you and definitely show some pictures of your setup. Enjoy your new toy. :)

FWIW, it's been a couple weeks now. TV hasn't fallen off the wall. It doesn't even wiggle.

A note on the Monoprice.com model 3900 mount. I had seen mention of the lack of a true 0 degree tilt and I can reaffirm that account. I have the adjusters cinched down to "0", but the TV still has a slight tilt. At a glance, it appears to be caused by the "hooks" on the TV side of the mount. There's the plate on the wall, then the portion that mounts to the TV and hooks on that plate. The grooves that form the hooks are thicker than the material on the wall plate. My guess is, that slack allows the top to pull forward and the bottom to push in. Having read about it, I expected it and it does not bother me. For others, it may be a problem.

The night after the install, I took a few pictures. They were rush though, since I was itchin' to play. The TV is a few inches higher than I had originally planned. Haven't decided whether to lower it or not.
http://gallery.tjapkes.com/d/23414-2/IMG_5903.JPG (http://gallery.tjapkes.com/v/Misc/album/panasonic_50pz80u/IMG_5903.JPG.html) http://gallery.tjapkes.com/d/23402-2/IMG_5898.JPG (http://gallery.tjapkes.com/v/Misc/album/panasonic_50pz80u/IMG_5898.JPG.html) http://gallery.tjapkes.com/d/23408-2/IMG_5901.JPG (http://gallery.tjapkes.com/v/Misc/album/panasonic_50pz80u/IMG_5901.JPG.html)