How big is the projector?

They aren't very big these days, butterfly style toggle bolts would absolutely hold it up with confidence.

Just be mindful when installing if there is insulation above.

It’s not too heavy, but heavy enough that I wouldn’t be comfortable with just drywall anchors. Same with the projector screen.

Honestly, if your asking questions like this, call a pro. The last thing you’re gonna want is it to come down on you or someone else.

If your ready to do minor repair work, you can use a small (1/8” or smaller) drill bit to drill into the ceiling every 1/2” or so until you hit the stud.

I’ve done projects like this before, but I’ve never had this much of a problem finding a joist. I’ve got no problem with patching a few holes, so this could work.

I wouldn't be comfortable with plug style anchors either.

Butterfly anchors on the other hand are not just adequate, they're ideal. There is 0 movement, shaking or jiggling here either ....once you snug it up tight, it's mounted until you take it down.

The projector screen, depending on size and if it's the kind that rolls up and down - yea, you'd want that into something structural.

Go up in the attic and look. Measure between 2, the spacing should be the same. Use the location to measure out to where you want to put the projector. Knowing about where the joist is, use the stud finder or tap on the ceiling and find the more solid sound.

Unfortunately I’m in a first floor condo, so no access from above.

Studbuddy

If you have decent hearing, you can knuckle tap the ceiling and find the studs. Or, you can blue light the ceiling and look for the crests and valleys. The first method is better, obviously

I had the same problem. The ceiling was textured and it was throwing off my stud finder and mechanical magnetic nail locator. I decided to buy a cheap metal detecting probe.... the type that metal detecting enthusiasts use while digging to pinpoint a find. It worked great, finding every nail. I used small round stickers to mark each one.

Building on this idea.

You have some partial results with your stud finder.

Knock around and see if you can hear where it is very solid. Combine those finding with the stud finder and magnet results. You'll find somewhere that you are 90% confident in.

Then, drill a tiny test hole and see if the drill is still getting resistance past 1/2" depth and comes out with some wood on it.

You can do this! I believe in you!

[deleted]

Is there a light in the room? Yes. Start measuring.

Why are huge sections magnetic?

If it is magnetic in lines going all the way across the ceiling: you have drywall hanging on resilient channel. Great for soundproofing! Unlikely you actually have this. These can be used as your stud.

If it is a huge magnetic section about 16" or 24" across and goes along the entire ceiling (measure where the magnet holds and releases): this is a sheet metal joist cavity air return duct for your floor or the floor above. These are done by slapping some sheet metal between joists and calling it a return duct. If you suspect this is the case, measure the distance between where the magnet lets go and the edges are your joists.

A few things, the drywall is probably mounted to metal rails that are attached in a perpendicular manner to the joists. This is very common in multi family building. It helps suppress sound transmission between the floors.

Find the AC register. It will most likely be be attached to a joist. Once you find one, the others will be 16” or 24” away.

1/4-20 toggles and it's done you would have to hang from it to pull it down.

Turn the lights off and hold a flashlight against the ceiling. Shine the light along the ceiling and you will be able to see the subtle texture changes. This should enable you to see the joints between the sheets of drywall, which should correspond with some kind of framing.

Maybe just do exploration hold 1” apart in a line. Small enough to be easy to patch. An awl is perfect for this.

You've tried all of the non intrusive methods, now it's time to go old school, get a hammer and nail and start nailing until you hit the first joist, then measure from there.

Magnet is your best friend

I hung a ladder on my garage ceiling by using a telescoping magnet on a stick. I was able to lock on to the drywall nails ,thus determining the studs.

I used these to hang both a projector and a projector screen from the ceiling drywall in an apartment back in college. They worked fine.

One thing I see often with DIY'ers is not knowing that most stud finders need to be calibrated when placed on the surface you want to find framing. Press it against the wall, hold it still, push the button and when you here "beep" then you can move it across. Sometimes you need to calibrate it in a different spot as you can't calibrate it over a stud.

I was just teaching a guy this at work the other day, he was watching me install some cabinets in a classroom and was admiring my Franklin stud finder, saying how his doesn't work. I pulled out my cheap 20 dollar one, and showed him how they need to he calibrated. Most stud finders work fine if you aren't going over plaster, double drywall, or a similar situation.

You could also use toggles of the projector isn't overly heavy. Or toggle a finished board onto the ceiling, round over the edges and paint or stain, then attach projector to that. A few toggles spaced apart over the board should leave nothing to worry about.

I didn’t know about this. Thanks!

Give it a try on the wall first, you'll see what I mean. Good luck.

Buy a good stud finder