Ideas for mounting a light fixture box in really thick plaster. (Home Depot, Lowes)

[Coldjensens]

We have very thick plaster in the cielings in some of our rooms. I cannot get a normal old work light fixture box to stay in becuase the ears that hold the box in place do not go above the plaster. I bought the deepest box that Home Depot/Lowes sells, it is nto deep ebough.

I cannot get in above the cieling and I would really strongly prefer to NOT rip out the cileing to put in the box. Does anyone know where i can get a reayyl deep light fixture box, or does anyone have any ideas whow I can mount this]e fixture?

[windtimber]

Try a ceiling fan bar. There are several models that fit up through the ceiling box hole then spread open driving spikes in the ends into the joists. I recall one version that had a threaded arranagement in the middle - spread it to hold then use an open end wrench to crank on the nut and drive home the spikes. Fish in the wires. Then hang the fixture box using whatever you can rig to the fan bar. The particular bar I'm describing was available at Menards a few years ago. Haven't looked for one for a long time.

[Cosmic]

You cut out the box outline as deep as it takes to get into a void area.

Then you slip in a piece of long wood(plywood is good as it will not split), just as wide as the opening, but longer than the opening. First screw a small drywall screw in the center of the strip of wood before attempting to position it in the opening. The screw gives you something to hold onto. The wood will slip in, if you slide it right, must go in a lot in one direction, position it up, flat above the hole, then pull it back over the hole, using the screw as a handle. Hold it with the screw and screw a long enough drywall screw at either end of the hole to catch / hold the strip of wood above.

This gives you a "Strongback" nailing / screw surface to further position addition shims (if required) to get the right depth for the box edges to sit flush.

Then the box can be screwed into place in the wood using the holes in back. Kind of a way to always get a secure nailing / screw attachment surface for anything to be mounted on a wall. Maybe a bit difficult to describe but typically very easy to do.

Must be very deep plaster or more than one ceiling installed. That trick works for most situations. You can also use this trick in standard plaster to get a screw surface if the lath doesn't provide / line up just right.

The thing to understand, is the wood will always slide in as a longer piece than the hole opening is wide if you do it right. The trick is to know to put a small screw in prior to have something to hold on as you position, secure the strongback piece.

Once done you do the standard putty up around the box with mud. Once you master the technique does not have to be much bigger than the box, many cases the light will cover any work foobaas.

[Coldjensens]

That is a really good solution. I will try that. Thank you. I can ust use the box that I have. It is deep enough, the screws on the ears that hold it in just are not long enough. UFnny how obviopus that solution seems, but I did not think of it despite fighting with this dumbthing for months trying to find some way to get it to stay in.

[Cosmic]

The beauty of that idea is if you are very careful, you can actually do the entire thing and not have to repaint, even a wee bit. The mud work / screws can be hidden under even a switch plate.

In your case, if you have snaked wires coming from above, you can just drill a big hole in the strongback piece of wood in the center. Use you finger in the hole to position / hold, don't need the screw and the hole later can serve to allow the wire and clamp on the box a place to pass.

I use this idea a lot when working behind walls for a large variety of things. Minimun pentration hole size, maximum holding power. Plus is super cheap, the parts are out of the scrap wood box.