+ Reply to Thread
Results 1 to 10 of 11

Hybrid View

  1. #1
    Join Date
    Apr 2013
    Posts
    3

    Question Q: Mounting 100+ lbs LCD to Drywall

    Hi everyone,

    A few weeks ago I decided we were going to mount our 55 inch LCD to the drywall. I watched a few videos and the process appeared to me at the time doable with my level of expertise (ubernovice). I ordered the tilting/swiveling wall mount but wanted some advise on several things before I bore holes on the drywall. Hope you guys can help.

    Here's what I have:

    TC-L55ET5 LCD TV (55.2 lbs)
    Monoprice PID 6200 Swiveling TV Wall Mount (guessing 60 lbs)
    6 x M8x90 Screws (came with the mount)
    1/2 Drill/Driver
    1/2 Drywall
    1 x stud

    The M8 screws are HUGE and the instructions are for engineers (see attached). This is what threw me off guard and started reading about different screw types and now I'm so confused on size, threads, pitches, pre-load, course/fine, grade/strength

    Q1) Found one (1) stud I can use (middle-left side). Should I use the massive M8x90 or can I use a smaller wood screw for the stud portion of the mount? One video I watched claimed he used a 300lbs rated wood screw and it appeared allot smaller than the M8x90.

    Q2) If using the M8x90, what size do I need to pre-drill in fractals? I've gone through several Google-ed guides on wall anchors and screws and I just couldn't believe how much science goes into using a screw.

    Q3) If using another type of screw, what size/grade/nominal/etc? Please recommend. I literally slept with a headache reading curiousinventor guide on screws (information overload ).

    Q4) Considering the approximate total weight of the LCD + mount is around 120 lbs, and two of the screws will be anchored in studs, how many more drywall anchors should I use? Will two (for total of 4) be enough for a swiveling (non-stationary) mount? Actually hoping that 4 total is sufficient for a secured anchor but I'm no engineer.

    Q5) Does the drywall anchor need to be rated for the entire weight (120 lbs) or more/less? I wasn't sure if the total weight will be divided into the number of screws used to anchor (ie: 120 lbs = 4 x 30 lbs anchors OR 120 lbs = 4 x 120 lbs anchors).

    I hope that I made sense. Also, thanks for reading through (if you have) the lengthy post. If I missed anything, please let me know.

    TIA,

    Zerocrew
    Attached Files Attached Files

  2. #2
    Join Date
    Oct 2012
    Location
    Houston, TX
    Posts
    295

    Default Re: Q: Mounting 100+ lbs LCD to Drywall

    The mounting instructions should tell you what size drill bit you need for pre-drilling your screw holes for the studs.

    The instructions should also tell you what size toggle bolts to use where you are not drilling into the stud. Those toggle bolts will instruct you what size of hole needs to be pre-drilled. Contact Monoprice for more help, their customer service is great.
    It's this old house, not this built after your dad was born house.

  3. #3
    Join Date
    Apr 2013
    Posts
    3

    Default Re: Q: Mounting 100+ lbs LCD to Drywall

    The 1 page instructions from Monoprice is unfortunately not for home users. I'll contact them and see what they can suggest. Thanks for the reply.

  4. #4
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    6,376

    Default Re: Q: Mounting 100+ lbs LCD to Drywall

    Do you what I would do?

    1. Use lag bolts, not screws. 3/8" x 4" at the minimum.
    2. Cut the drywall where the TV will be mounted, then install 4x6 or double 2x6 blockings between the studs for those bolts to anchor.

  5. #5
    Join Date
    Dec 2007
    Location
    Tennessee
    Posts
    1,710

    Default Re: Q: Mounting 100+ lbs LCD to Drywall

    The back panel should be about 36" wide or a little more, that way it can cover three studs. The studs should be 2x and about 16" apart. If you don't have a good stud finder, you should get one, but if you have found one stud, the others should be easy to find. Be sure to locate the center of each stud.

    You can drill a series of holes with a 1/16" drill bit about 1/2" apart to locate and find the center of each stud, the TV will cover up the damage, or the mount will. Once you locate the studs, determine the height of the mount. You need a level for this, if the level isn't as long as the mount, then you can use a straight edge, but you need to draw a line for the bottom of the mounting plate.

    Set the mounting plate on the line. There are two rows of holes in the mounting plate, one across the top and one across the bottom. You can adjust it back and forth as long as you have three holes on each row over a stud. Mark those holes on the wall and then take down the mounting plate. Now drill the pilot holes for the 8mm x 90 screws. These appear to be high strength lag bolts so don't substitute something else for them.

    It looked like the instructions called for a 10mm drill bit but that is too large. A 3/16" drill bit should be about right for the pilot hole, go as deep as the drill bit allows. Now mount the plate to the wall with the 6 8mm x90mm bolts. It will take a lot more than 120 lbs to pull this plate off the wall.

    The other plate mounts to the back of the TV, then you, with the help of a couple of friends holding the TV in position, connect the plates together with the swing arms.

  6. #6
    Join Date
    Aug 2007
    Posts
    6,963

    Default Re: Q: Mounting 100+ lbs LCD to Drywall

    The mounting plate should be plenty wide enough to span at least one stud bay (typically 16" centers ), if not two, which means you should be able to mount the bracket directly into studs. DO NOT attach to the drywall only, unless you want an expensive trash can weight in the form of your new TV lying in pieces on the floor.

    When drilling pilot holes, choose a drill bit that is the diameter of the fastener shank (threaded portion sans the threads ). Say you have a 1/2" lag bolt. The height of the threads are 1/8" on both sides, which means the shank would be 1/4", you would then use a 1/4" drill bit for the pilot hole. This is just an example, the numbers are merely for explanation. In reality, the easiest way to size the pilot bit to the bolt is to hold the drill bit up to the bolt and select the bit that is the same size or just shy of the shank diameter. You want to just barely see the gullet of the threads (bottom of the valley between each thread ) on either side of the bit.

    As was mentioned, you can use a small nail and tap it into the drywall to find your studs, and more importantly, find the center of those studs. Hold the mounting bracket on the wall where you want to place it. Mark it's width and the line where one of the mounting rails will be on the wall. Using a nail, probe the drywall along this area to find your studs, go about 3/4" spacing until you find a stud, then probe to find it's center, from there you can measure 16" to find the next stud, then nail probe to find center.

    Once you find the stud, drill one pilot hole, set the mounting bracket, and start the bolt, then mark your other pilot hole locations. Take the bracket down, drill pilot holes, mount the bracket.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  7. #7
    Join Date
    Apr 2013
    Posts
    3

    Default Re: Q: Mounting 100+ lbs LCD to Drywall

    Thanks for the replies dj1, keith3267, A. Spruce. Appreciate you guys taking time to look into this.

    @dj1: I'll be able to use two (2) of the M8 lag bolts that came with the mount (it came with 6) since I'm only able to hit 1 stud. Don't have experience in cutting drywall to install studs but I would try that if I knew what I was doing

    @keith3267: The wall plate is 18" but I'm unable to adjust the position of the wall plate due to a fireplace on the left and a window on the right. I used the Zircon e40 to locate the stud center and actually used the smallest drill bit I have to verify (e40 already told me there was a stud where there wasn't in my bedroom :P). I'll use the 3/16 as reference for the pilot hole for the M8 along with A. Spruce's suggestion. I'm only really able to use 2 of the M8 lag bolts provided as I'm unable to find toggle bolts / wall anchors that can accommodate the M8. I'll look some more maybe the hardware store just didn't have it.

    @A. Spruce: I'll use the one stud for sure. Thanks for the tip on how to determine the pilot hole for a particular screw. I'll use this method from now on.

    Looks like I might end up having to use drywall anchors in-place of the M8 lag bolts that came with the mount. Two (2) 200lbs rated molly bolt / toggle bolt enough? Or should I shoot for 4 additional anchors? I'm also still waiting for Monoprice's response to the same questions.

    Zero

  8. #8
    Join Date
    May 2012
    Posts
    137

    Default Re: Q: Mounting 100+ lbs LCD to Drywall

    Quote Originally Posted by zerocrew View Post
    Looks like I might end up having to use drywall anchors in-place of the M8 lag bolts that came with the mount. Two (2) 200lbs rated molly bolt / toggle bolt enough? Or should I shoot for 4 additional anchors?
    Zero
    OMG...run, don't walk to a contractor who can do this for you.

    Absolutely - do NOT mount it to the drywall.

    BTW, I highly doubt your bracket weighs 60 lbs...

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •