ᐅ Suspending a ceiling with precast concrete hollow core slabs
Created on: 13 Dec 2025 08:02
F
fototeddyF
fototeddy13 Dec 2025 08:02Hello,
we are currently renovating an old building. The ceiling on the ground floor consists of double-T beams, into which hollow-core slabs are placed, with concrete poured on top.
Now, we want to redo the ground floor ceiling. So far, the battens have been made from treated wood slats, which were fastened lengthwise to the T beams, with a layer of slats across underneath, followed by drywall panels.
I would like to install a new suspended ceiling using direct hangers and continuous UD channels around the perimeter. Regarding the hollow-core slabs, I’m wondering if and with what kind of fastening materials I can attach the direct hangers to them. I would prefer not to fasten directly into the T beams, as I believe I can work better with the hollow-core slabs using the tools I have. But do the hollow-core slabs alone hold the load, or do I need to fix into the concrete above as well?
Are ceiling nails sufficient for this, or are there suitable anchors that are approved for use with direct hangers?
Best regards and many thanks for any advice.
we are currently renovating an old building. The ceiling on the ground floor consists of double-T beams, into which hollow-core slabs are placed, with concrete poured on top.
Now, we want to redo the ground floor ceiling. So far, the battens have been made from treated wood slats, which were fastened lengthwise to the T beams, with a layer of slats across underneath, followed by drywall panels.
I would like to install a new suspended ceiling using direct hangers and continuous UD channels around the perimeter. Regarding the hollow-core slabs, I’m wondering if and with what kind of fastening materials I can attach the direct hangers to them. I would prefer not to fasten directly into the T beams, as I believe I can work better with the hollow-core slabs using the tools I have. But do the hollow-core slabs alone hold the load, or do I need to fix into the concrete above as well?
Are ceiling nails sufficient for this, or are there suitable anchors that are approved for use with direct hangers?
Best regards and many thanks for any advice.
Hi,
I wouldn’t rely on just the hourdis panels, even if the anchors initially seem “secure.” The panels are filler blocks and don’t provide any structural backup, and with a ceiling load of 15–20kg/m2 (3–4 psf), it becomes borderline over time. If you’re going to drop the ceiling, at least anchor it firmly into the topping slab—30–40mm (1–1.5 inches) of real concrete makes a noticeable difference. Drop ceiling nails are not reliable for this; that’s more wishful thinking than proper technique. Do you know the actual thickness of the topping slab, or has that never been properly documented?
I wouldn’t rely on just the hourdis panels, even if the anchors initially seem “secure.” The panels are filler blocks and don’t provide any structural backup, and with a ceiling load of 15–20kg/m2 (3–4 psf), it becomes borderline over time. If you’re going to drop the ceiling, at least anchor it firmly into the topping slab—30–40mm (1–1.5 inches) of real concrete makes a noticeable difference. Drop ceiling nails are not reliable for this; that’s more wishful thinking than proper technique. Do you know the actual thickness of the topping slab, or has that never been properly documented?
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