Stone Dry-Hanging Calculator
Mullions, rails, brackets and panels in one pass.
Inputs
Result
Formula
| Panels = ceil(W ÷ panel W) × ceil(H ÷ panel H) | |
| Mullions = ceil(W ÷ spacing) + 1; length = count × H | |
| Rails = ceil(H ÷ spacing) + 1; length = count × W | |
| Brackets = panels × 4 | four corners each |
30×20 m stone façade with 900×900 modules, mullions at 1.2 m and rails at 0.9 m: 34×23 = 782 panels, 822 with 5% waste; 26 mullions totalling 520 m and 24 rail rows totalling 720 m give 1240 m of steel at 4.5 kg/m = 5.58 t; 3128 brackets, 9.3 kg/m² of steel.
FAQ
Why is dry hanging so much dearer than wet fixing?
It brings a whole steel frame: mullions, rails, brackets, cast-in or post-installed anchors, corrosion protection and fire stopping - 5-9 kg/m² of steel alone. In return the stone is not glued to the wall (no efflorescence, no hollow spots, nothing falling on people), individual panels can be replaced, larger modules are possible and seismic performance is far better. High-rise façades are now effectively required to be dry hung.
Is 9 kg/m² of steel normal?
High but within reason. Common practice is 4-7 kg/m²; 9 arises because 900×900 modules mean more joints and denser rails. At 1200×1200 with 1.5 m mullion spacing it drops to about 6 kg, but stone thickness and bracket capacity must increase. It is a trade-off between stone and steel, settled by the façade calculation, not by guesswork.
Why higher waste for shaped work?
Natural stone varies in veining and shade even within a block, so book-matched joints and corners need selection. Shaped cuts - curves, mitres, window surrounds - remove large offcuts, leaving 60-70% usable. Stone is brittle too, with 2-3% breakage in transport and installation. All of it belongs in the waste figure.
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Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.