I'm thinking about mounting a flat screen on my wall. Problem is I have plaster & lathe walls. Here's my plan. Mount a 3/4" plywood backer board using 3" lag bolts to the studs big enough to securely hold the wall mount bracket. Mount the bracket to the backer board using many, many 1 1/2" lag bolts. Thoughts?
Brian I see nothing wrong with your plan. The problem with lath and plaster walls is that the laths are attached to the wall studs with small nails making the laths very brittle and easy to let go of the wall studs. The plaster is attached by the plaster that passes between the laths and when it becomes dry it bonds itself to the laths. Over time it becomes brittle and becomes loose. This makes the plaster unsuited to hold anything that weight much over 5 to 10 lbs. It is also not a very good anchor point for attaching your plywood. If bridging multiple wall studs with a 3/4 inch thich piece of plywood you will get most of your holding power by lagging into the wall studs themselves. The studs should be between 16 and 18 inch centers however may be as wide as 24" depending on who built the wall. I would recommend spanning of at least 3 studs if possible but here again it will depend on the weight of you TV. I worse cases I would open the area behind the intended TV placement and maybe add some additional support.
Since the TV is held by two brackets, if you can fit it in a location where both brackets are screwed into the wall studs I would think that would sufficient.
Hi Jay. Thanks for the reply. I like the idea of opening the wall and adding more support. That way I could build 2x4 supports in the wall to secure the wall mount.