photo of ceiling and electrical box

I'm replacing an old fixture... Its base was quite wide (about 7"), and had a large integrated crossbar similar to Atron's UB1. The installer fastened this directly through the ceiling materials (screw holes circled) instead of the electrical box, crushing some of the ceiling tiles so the surface around the hole is no longer flat. This is an issue as the replacement fixture's base is smaller.

The steel round electrical box is about 3.25" diameter. The threading of its ears is unknown or damaged - it wrecked the 8-32 screw I tried. I would like to replace the box, but this is unlikely due to the mess it would involve.

drawing of ceiling structure

Ceiling structure
1. Blown-in paper/cellulose insulation
2. Multiple layers of pink fiberglass insulation sheets
3. Burlap/wool blanket-looking sheets
4. Joists, electrical cabling, filled in with scary particle insulation
5. Boards fastened joist bottoms, not sure how sparse these are. Maybe old pine baseboard?
6. Electrical box fastened to board. Could not see into this layer, probably more wood boards to mount the drywall, probably more loose insulation
7. Drywall layer, starts beneath edge of electrical box
8. Wooden lattice to support ceiling tiles
9. Ceiling tiles (fiberglass?)

Possible solutions so far:

  • Expand the hole beneath the electrical box to attach a 4" diameter box extension. This would add stable new ears with new threads, near the current ceiling surface. Probably means re-threading the old box's ears, and the hole might expose questionable insulation.
  • Find a large crossbar (or cut one out of sheet metal?), wide enough to cover the crushed tiles and provide a flat mounting surface.

Any choice will probably need some form of medallion / "goof ring" to cover the marked up tile area, so my only real concern is securely attaching the fixture.

  • What does the new box look like. You shouldnt be expanding the hole in the joist Aug 13, 2023 at 7:15
  • It is this one: link. Picked it up randomly and it happens to be approximately the right height.
    – Toglik
    Aug 13, 2023 at 16:13
  • Round means it's a mud ring. Cut a 4" square around it and put a new one if the threads are damaged (or just tap it for #8 instead of #10... or #6 instead of #8). Then a medallion. And use the safety chain into a joist if it's a fan; that's supposed to be a 'fan box'.
    – Mazura
    Aug 13, 2023 at 18:18
  • If it's too far up in the ceiling then you need two, 2" uh... #8s? 6s? I can never remember; that's why I have a #6 kit and a #8 kit of varying lengths. One of them does cover plates and the other does device (box?) screws. Exterior boxes (your link) are some weird thread so watch out for that.
    – Mazura
    Aug 13, 2023 at 18:28

1 Answer 1


Your solution of adding a box extension and medallion is a good idea and should work well.

Wear eye and breathing protection when expanding the opening for the box extension. It should only be dangerous if you breath it for a long period of time and this is minimal.

Try to get ahold of Self tapping screws to attach the box extension.

You know the rest of the procedure, medallion and fixture anchor.

Good Luck

  • Any suggestions on minimizing the amount of insulation that would fall through the hole? I haven't come up with anything that seems feasible while on a ladder and cutting with one hand, except maybe start with a small hole and shoot a bit of spray foam in...
    – Toglik
    Aug 13, 2023 at 16:20
  • The insulation loss should be inconsequential. Unless you are cutting far wider and deeper than needed.
    – RMDman
    Aug 13, 2023 at 16:25
  • More concerned about the mess, it slides like sand. Exposing an inch-wide hole 12 inches long may allow quite a bit to fall through, if it's sitting directly on the drywall.
    – Toglik
    Aug 13, 2023 at 16:52
  • 1
    If it is like sand it is not likely insulation. put down a drop cloth. Many home repair tasks are not clean, you just have to deal with it.
    – RMDman
    Aug 13, 2023 at 16:54

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