ᐅ Looking for a sturdy board to mount a pendant lamp

Hello everyone,

We want to hang a lamp made up of about 15 glass spheres, each weighing around 2 kg (4.4 lbs), in our stairwell. The installation will be at the top of the sloped ceiling, and the lamps will hang over two floors in an open space.

Currently, the ceiling is covered with Knauf hardboard panels, and we plan to mount each sphere individually using flush-mount anchors.
Distributed over the ceiling area, this results in about 14 kg (31 lbs) on roughly 0.7 sqm (7.5 sq ft) of Knauf panels. Scaled up to 1 sqm (10.8 sq ft), the load would be about 20 kg/sqm (4 lbs/sq ft), whereas according to the datasheet, the Knauf panel can support 14.4 kg/sqm (3 lbs/sq ft) when using cavity anchors—so this is too much. Additionally, the panels would end up with many holes.

Therefore, we would prefer to replace the 18 mm (0.7 inch) Knauf panel with a wooden board or similar material that can easily support the load. The surface would then be plastered over.

What material or type of wood would you recommend here?

Thanks in advance for your input!

Hello,
how about using a plywood sheet with a phenolic overlay? A thickness of 18 mm (0.7 inches) usually costs around 20-30 euros per square meter (about 2-3 USD per square foot) if you buy a whole sheet, or about 45-50 euros per square meter (around 4-5 USD per square foot) for a precise cut. It is bonded with waterproof glue and very sturdy. You can get it at any decent home improvement store.

I would suggest talking to the painter first to check if the joints between the phenolic plywood and the gypsum boards can be finished well?!

Best regards,

Andreas

Yes, plywood with phenolic film overlay is practically the highest level of load-bearing capacity. However, it needs to be sufficiently large to distribute the load evenly over the supporting structure.

Thanks in advance for the input! I’ve asked my painter about the surface. The board will be about 90x100cm (35x39 inches). The three battens shown in the attached photo are underneath as the support surface for fastening screws (there is also a batten below next to the purlin, visible at the far end of the photo).