Hmm interesting! My high school has similar tiles. As long as the asbestos is not disturbed it's allowed to stay. I wished they would have installed a nice drop ceiling in the hallways and classrooms since it's so ugly with all the pipes, conduits, and wire ducts on the ceiling, as well as the exposed steel I beams.

I wonder if those tiles were common in 50s public buildings. I've seen them in older schools here and was also used at one point in the 50s subway stations. Yeah a drop ceiling looks a lot better than having all those exposed pipes, conduits and beams. Although I kinda wished they moved the pipes into the old ceiling plenum when they tore out the old ceiling. They left the pipes as is and installed a drop ceiling below the lowest pipe which makes the ceiling a bit low imo.

It's kinda hard to tell but the two pics show the same section of hallway. The exit sign in the older picture is where the one in the newer picture is now. Wonder if they also buried it in the ceiling lol.

Those tiles were pretty common in the 50s. I've even seen homes with those tiles in basements and screened in porches that were turned into enclosed interior rooms. My middle school used them in some of the rooms and used a drop ceiling in other parts. I believe the drop ceilings are original so I don't know why they used the tiles in some rooms. Only a few had the tiles and they were all non-core classrooms.

I wonder if they still make those style tiles, I kinda doubt it since I've seen them replace broken ones with white pegboard but it could be because they're too lazy to order the right type tile. Pegboard actually works somewhat well since the 50s tiles were screwed into furring strips on the ceiling instead of laying into a T bar like in modern drop ceilings. Interestingly only a quarter of the building used ceiling tiles, the rest of the building originally had a metal lath and plaster ceiling although much of that has either been removed or covered up with a drop ceiling. Kinda rare to see that or even drywall in newer institutional buildings.

Anyway, another common type of 50s ceiling tile, the 1x1 ones are still made. I also saw a few NOS boxes of them at one of the local Restores.

Oh you know what, it was the 1X1 tiles that I've seen. Never seen the bigger ones above. I just assumed they were 1X1 in your picture. At my middle school they actually spot replace those 1X1 tiles with drop ceiling tiles screwed into the ceiling. The original tiles have no visible screws but the replacement tiles had visible screws and fender washers (probably to prevent the screw from being sent too far into the tile and ruining its integrity). Looked kinda ugly but at least the tiles were a similar pattern so it didn't look AWFUL. It did look odd to find a 2X4 drop ceiling tile screwed into the ceiling among 1X1 tiles loll. When I first started there I thought maybe it was an access point to above the ceiling but all the rooms with the tack-in tiles are on the first floor so that's not possible. But throughout my time there I noticed more 2X4 tiles pop up so I figured out they were spot replacing cracked ones since they were asbestos.

My university still has a lot of buildings with asbestos stuff, there's signs to not disturb the ceiling tiles, pipe insulation on the door of boiler rooms, etc. One building, built in (at least dedicated so presumably built) in 1972 has such a sign for a basement boiler room, and the not-yet-redone rooms have these tongue and groove? 1X2 ceiling tiles with the same texture as some of the drop ceiling ones...but no grid. Does that make sense? They also have 1X4 air handling troffer fixtures in those rooms. The remodeled ones have modern drop ceilings and 3 lamp 1X4 parabolic troffers.

Yeah, here's a better shot of the tiles. I'm pretty sure they contain asbestos. The boiler pipes at my school also have asbestos. This is also one of the few remaining rooms that still have that tile ceiling. A lot of them got the ceiling removed when they were wiring in projectors and replaced with regular 2x4 tiles and lay in troffers.

Yeah even some of the drop ceiling tiles at my high school had asbestos. They were all full of holes from kids throwing pencils at them "back in the day" lol. The newer ones are harder and rigid, so you'd need some throwing darts from a dart board to pierce them lol.

I have a feeling the ones used in my high school (built 1968) had asbestos since I don't think they replaced any of the tiles. They even reused tiles when they went from continuous row 1x4 troffers to 2x4 troffers to cover up the holes left by the removed 1x4 troffers. Personally they should have installed LBF ballasts and 25w lamps instead of replacing with 2x4 troffers. The few classrooms that still had continuous row 1x4 troffers were better lit than the retrofitted ones.