How should I insulate my block / cement ceiling?

I have a room that was once a storage shed/room attached to the back of our home. (By the previous owner.) The ceiling of the room holds a cement deck above it and is steel beams and what appears to be bricks or cinderblock between the steel beams. The room is framed out with studs and drywall on two of the sides. But the other two walls are brick and cinderblocks.

The previous owner had what was a 2" thick sheet insulation glued to the ceiling. I noticed there was water, or condensation, dripping from it at the end of the summer. Not being sure if it was the ceiling leaking, or not, from the deck above. I removed the insulation. I patched what cracks were visible in the above deck and there hasn't been any signs of anything leaking.

Now I would like to re-insulate the ceiling. Cause the room is getting very cold now that winter is approaching.

My question...what recommendation would you have to insulate the ceiling again?

I have looked online and it appears most insulations are not fire resistant, and if used, should be covered by some other material. ie. wood or drywall. I don't believe nailing or screwing anything into the ceiling (with it being a concrete deck above) or an insulation would be good. I am fine with gluing it. I would like suggestions on insulations that would be fire resistant and is ok not being covered by wood or drywall and just being painted. I would rather do this myself. See photos attached of what the ceiling looks like.

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3 Answers

  • Anonymous
    2 months ago

    I like your answer. Though having the two light fixtures on the ceiling. I wasn’t sure if the heat from them could catch the foam insulation on fire. Hence the concern for the fire resistant. But I agree, we won’t be intending to hold any flames in the room or near the ceiling.

    The second thing is, there is hot and cold water pipes that are at the one corner of the ceiling. They just weren’t visible in the photos. Though, they didn’t appear to be wet or causing the wetness. For the wetness was nowhere near those pipes.

    Any additional thoughts would be greatly appreciated.


  • 2 months ago

    here in uk it would be called a block and beam construction ..except the beams would be reinforced concrete ..not steels ..your problem is simple prevent condensation forming there must be no air gaps between insulation and underside of roof ..the fact the beams are steel make this extremely difficult we can get foam blown on ..this seals it completely ..but its not a diy job can refix sheet material like celotex or kingspan ..but no guarantees you will stop it 100%

  • Anonymous
    2 months ago

    2" foam insulation AGAIN.  The moisture was condensation.  You do not have plumbing lines(which would be copper tubing or black plastic) so the water was condensation(from breathing) watering plants in the room(evaporation=condensation on a ceiling) especially if there is no air flow (breeze of a fan to move warm air around) As foam is plastic, it does not absorb moisture like wood joists do.  I prefer the blue(or pink) styrofoam because it is easy to glue up with some glue that does not eat the foam.(that would be stinky contact cement which has acetone or lacquer thinner in it...both  melt the styrofoam plastic. Fortunately, they now make a water based contact cement so the harsh chemicals are gone. (yeah, white bubble styrofoam is cheaper but is harder to cut-smoothly as little bubbles come off.

      HOME DEPOT has an adhesive in a 12" tube like PL400 that should work. Read the tube. Ask the staff which one they recommend.. If you get the moisture build up again, know you do not fix it from the inside but do it from the outside.  Yeah, styrofoam will burn. but who the hell is going to start playing with matches near the ceiling?  Even drunk, you don't do that.    You can paint styrofoam with latex paint like a regular wall and the paint is the protection against flame.   Styrofoam does not immediately catch fire as it melts away more. Get a cup from Micky D and put a match to it.  It is the same styrofoam.It will not burst into flames.   "That is Hollywood fake situations"  "Attack of the killer foam....oooeeeoooo."

    Cutting foam can be done on a table saw, hand saw or jig saw with a knife blade(no teeth) and can be sanded by hand with sandpaper about 100 grit.     (I was making airplane wings so had to cut an airfoil pattern so a curve and the knife just cut like a hot knife through butter.  Foam is dust free and rodents or other bugs won't like it as it is not edible. or nesting material so they won't be there.  Even 1" is better than nothing.  1" is cheaper than 2" and if you want you could always add on another inch say next year by gluing on foam to foam using carpenter white glue and leave the supports holding it up for a week as plastic does not allow air in so the glue dries all that fast.

    Disadvantage of the contact cement is as soon as you touch, BAM it is stuck together.  No chance to adjust it by sliding it.

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