Is my garage ceiling plaster or some other material?

[heyjoe91]

My house was built in 1953. I would like to insulate the ceiling in my garage since there is no insulation. I have done insulation and sheetrock in the past and am confortable working with my hands. The rest of my house is plaster but the ceiling in the garage looks like some sort of concrete (I'ts a hard surface and rough). Is this just a thin coat over the plaster or was a different material likely used for a garage? Just want to know what I'm getting myself into before I start. Thanks for the help.

 

[Mercy]

Plaster was done in multiple layers, the first coat being more gritty and grayer than the finish coats. Drywall here wasn't until mid 60's. I would either a) assume it's plaster and drill a small, patchable hole in it to verify, or b)try and see the other side of the ceiling via an access panel, attic, or though the floor from upstairs. We had wide plank floors and popped them out to install a ceiling fan downstairs.

 

[Thorold]

There was also an asbestos based paneling that was common in garages in that era. One example was Celotex and one type of it was asbestos.

 

[Shocker]

Also, in my home (1954) I have the earliest version of drywall called Gypsum Board (brand name). It is harder on it's surface than drywall and plaster, more like cement.

It is dimensionally different than drywall. Too think or too thin depending so make sure you plan when you cut.

 

[Zeke]

You most likely have only the brown coat and no putty or finish coat. Brown coat is sand and gypsum over gypsum or wood lath. It's floated out to gain a straight surface for the final coat. Not necessary in a utility space. It does qualify for a one hour wall.