A standard plasterboard (BA13) fixed to the ceiling does not support weight in the same way as a wall. The resistance depends less on the board itself than on the metal framework that holds it. Confusing the two risks tearing or deforming the false ceiling.
Framework, furring strips, and overload: what really determines the strength of a plaster ceiling
The common reflex is to look for how many kilos a plasterboard “holds.” The question is poorly posed. It is the framework (tracks, furring strips, hangers) that bears the load, not the plasterboard alone.
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A plaster ceiling is designed to support an overload of approximately 20 kg/m² beyond the weight of the ceiling itself. This figure includes a safety factor and covers typical loads: insulation placed above, lighting fixtures, or wind effects on the structure.
To delve deeper into the weight supported by a plaster ceiling, it is necessary to distinguish between two situations: fixing an object directly into the board or taking it from the framework. The difference in capacity between the two is considerable.
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When a hook or a plug is screwed solely into the plasterboard, without reaching a furring strip or a beam, the resistance to tearing drops to a few kilos per fixing point. Manufacturers mention a limit of 6 to 8 kg per point for a direct fixing in the plasterboard on the ceiling, which is barely enough for a small ceiling light.
Fixing in the plasterboard alone or taking from the framework: two very different capacities
Fixing an object to a plaster ceiling without touching the framework is like suspending weight from a 12.5 mm thick sheet of plaster held by cardboard. The board eventually deforms, then gives way around the drilling point.
Direct fixing in the board
This type of fixing is suitable only for light loads. A smoke detector, a small light fixture, a decorative hook. Beyond a few kilos, the board cracks under vertical tension.
- Toggle or spring plugs: they distribute the load over a larger area behind the board, but remain limited to light objects on the ceiling
- Metal expansion plugs (Molly type): their resistance is greater than that of plastic plugs, but on the ceiling, gravity constantly works against the fixing
- DCL box (connection device for lighting): designed for light fixtures, it is normally fixed to the framework, not in the plasterboard alone
On the ceiling, gravity exerts a constant pulling force on the fixing, unlike a wall where the load mainly works in shear. A Molly plug that holds 25 kg on a vertical wall may give way at 8 kg on the ceiling.
Taking from the framework or the load-bearing structure
To suspend an object weighing more than a few kilos, the fixing must pass through the board and screw into a metal furring strip, a load-bearing track, or directly into a wooden beam if the ceiling is fixed to a framework.
In this configuration, the board serves only as a facing. The load is transferred to the load-bearing structure, which has a much higher capacity. A ceiling fan, a heavy chandelier, or a projector require this type of support.
How to locate furring strips and beams before drilling a plaster ceiling
Drilling randomly in a plaster ceiling often results in hitting empty space. The metal furring strips are spaced regularly, but their exact position varies by project.
A stud finder remains the most reliable method. Magnetic detection models locate the screws that fix the board to the furring strips. Electronic models detect the density of the material behind the board.
The tapping technique also works: the sound is dull over a furring strip, hollow between two. Once the first furring strip is located, the others are usually found at regular intervals (every 40 or 60 cm depending on the installation).
Identifying the framework before drilling is the only way to ensure a reliable fixing. Without this step, even the best plug remains a gamble.
Distributed loads and point loads: think in square meters, not total kilos
Consumer articles often talk about the weight of an isolated object: a 5 kg light fixture, a 12 kg projector. This approach masks a determining parameter: the distribution of the load over the surface of the ceiling.
The admissible overload of about 20 kg/m² is understood as a distributed load. Concentrating 15 kg on a single fixing point is not comparable to distributing 15 kg over four points spaced 50 cm apart. In the latter case, each point bears only a few kilos, and the board works uniformly.
For a heavy object, multiplying the fixing points and distributing them over several furring strips reduces the stress per point. A projector mount with four screws spaced apart, each screwed into a furring strip, distributes the load over the framework instead of concentrating the pull on a single hole in the plaster.
- Point load: a single fixing point, high risk of tearing beyond a few kilos in the plaster alone
- Load distributed over the framework: several fixing points screwed into the furring strips, the board experiences almost no stress
- Surface load (insulation placed above): the weight naturally distributes over the entire surface, which is the case provided for by the 20 kg/m² admissible overload
A plaster ceiling is not a floor. Its primary function is to cover, not to bear weight. Every kilogram suspended must be considered in relation to the distance to the framework, the number of fixing points, and the type of plug. Exceeding the few kilos admissible for direct fixing in the board without taking the load onto the load-bearing structure remains the most frequent cause of light fixtures ending up on the floor.