ᐅ Steel beam in concrete ceiling – how to plaster around it?

NOUSEFORANAME schrieb:
To explain a bit more precisely.
Our ceiling will NOT be plastered. [...] So unfortunately, applying mesh onto the concrete ceiling is not an option.

With a fair-faced concrete ceiling, the designer surely must have been aware that this also means the steel beams in between will be visible, or if they wanted it otherwise, they should have prepared a detailed execution drawing for that.

As shown in the photos, I only see the option to fill the chamfered, clean joint and leave the steel beams visible (personally, I would find it more attractive to paint them in a concrete-gray tone).

If the steel beams are to be filled only, without mesh extending onto the concrete surface, then a metal mesh as a plaster carrier/reinforcement will likely need to be spot-welded onto the steel beams. Has the designer considered this?

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We also have a steel beam in the hallway and no plaster on the ceilings.
The plasterers filled it in for us. I don’t know if anything was applied underneath.
There should be some kind of (installation) adhesive to fix reinforcing mesh to metal and then cover it with filler.

We did not plaster the lower part of the ceiling and only painted it, including a corner beam. It is not visible. The plasterer covered it with the final coat as well.

We have a similar issue, except that the beam is almost flush with the concrete ceiling, so there’s not much room left for plastering.

At the time, we informed the general contractor about this, and it was agreed that steel plates would be installed underneath, but this was never done. As a result, the beam is flush, and the contractor was fired.

In your case, I would have removed some material along both sides of the beam so that, for example, expanded metal mesh could be placed in between and fixed with mortar or welded directly to the beam (as mentioned before).

How was the problem resolved?

NOUSEFORANAME schrieb:
To explain more precisely: Our ceiling will NOT be plastered. It will also not be covered with drywall, because the recessed spotlights are already planned within the concrete ceiling. So unfortunately, applying mesh tape on the concrete ceiling is not an option.

Exposed, bare concrete?
Or one layer of painter’s fleece, then painted?

For us, the ceiling looked like this with mesh tape:

This is bridged with reinforcement mesh up to 20cm (8 inches) over the concrete, then plastered. The socket openings are not an issue at all, as the holes are incorporated into the plaster.

The reinforcement mesh can be easily adhered to both steel and concrete, so there is no need to make a big deal out of it.

Using painter’s fleece on the final plaster helps prevent visible cracking in the end.