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I have a question regarding heavy drywall hanging on a ceiling.

I need to hang drywall ceiling without any studs (drywall designed for moisture, vapor barrier, straight onto concrete ceiling).

I realize the proper way to to do this would be metal studs, however, I can not lower the ceiling any more than 2 cm to preserve the large room separating arch thing.

My question is about weight, the building is an old conrete block one, appartement is on 4th floor drywall is 125x1200x3000mm (room size is 4x3m. The drywall weight is around 35kg, I will be trying to distribute the weight from edge to edge to get some support from the walls instead of leaving one drywall sheet solely hanging in the middle.

Do I have anything to worry weight wise? As in, is it safe to mount around 110 kg of weight onto the ceiling that is roughly 3x4m in area?

For reference, the build is an old concrete block design: https://gyazo.com/09e079faf29c2988ef0b8ac8b237e49b.png

Drywall is: "knauf gkbi 125x1200x30000mm".

  • Is drywall typically attached to those ceilings? Have you considered something you can paint on as a coating instead? – fixer1234 Sep 21 '18 at 18:37
  • I have always used hat channel or furring strips I would not trust construction adhesive over head. As far as the weight I would not be worried about that. Have you thought about coating the surface instead of sheetrock. – Ed Beal Sep 21 '18 at 18:43
  • I have, the thing with these old european building is that the ceiling conrete block joins are always impossible to hide with couting alone. Drywall is the only option. And it will not be adhesive, It'll be held by screws drilled into concrete. My only worry was the actual weight. – David freemmaann LT Sep 21 '18 at 19:01
  • drywall weighs a lot less than concrete. – Jasen Sep 22 '18 at 7:07
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Drywall weighs 8 lbs. per inch of thickness. Plaster weighs 10 lbs. per inch of thickness. This is insignificant in the design of buildings.

Changing a light fixture to a heavier fixture could have a bigger impact.

I’d worry more about the kind of fastener you are going to fasten the gypsum board to the concrete slab. Typically reinforcing steel is placed with 3/4” clearance between the bottom of the rebar and bottom of the slab.

Be careful not to screw 100 screws into the rebar and cause spalling (loss of bonding).

  • This is not a place that will ever be damp and even if I do reach rebar I typically insulate the area with some coating to not moisture get through the screw. I do appreciate the answer, however. This was very helpfup and exactly what I needed, thank you. The only worries I had were regarding the extra weight that the ceiling will have to support. Thank you. – David freemmaann LT Sep 21 '18 at 22:02
  • Yes, moisture affecting the rebar (rusting) is a major problem, but I was more concerned about reducing the amount of bonding between the rebar and concrete. One of the key factors affecting the structural stability of reinforced concrete is bonding. The reinforcing steel must be bonded adequately to the concrete in order for it to be stable. Be careful screwing into the concrete and causing the concrete to sprawl and exposing the rebar. – Lee Sam Sep 21 '18 at 23:09
  • I see, I will try to only screw it in every half a meter or so with some more heavy duty screws. Sheet is not really flexible, so should be enough. Thats around 18 screws per one sheet which I don't think is that bad. The metal studs would have had roughly the same amount. – David freemmaann LT Sep 22 '18 at 6:39

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