Granite cladding dry fix vs wet fix: decide by wall and height, budget last
Granite cladding dry fix vs wet fix: wet fixing is enough on low walls with a solid backing and small units. Facades, tall buildings, large panels and old walls go to dry fixing. Judge the wall height and backing first, panel size second, budget last. A 30 mm panel weighs 81 kg/㎡, and the wet bed adds about 40 kg of mortar; that extra weight is mortar, not stone.
Granite cladding dry fix vs wet fix: why do boundary walls and facades get different answers?
Start with the answer. On low walls, such as boundary walls, gate piers and ground-floor plinths, over a solid masonry or concrete backing, and with small units such as 600×300 mm, wet fixing (mortar-bed fixing) is adequate. External facades, tall buildings, large panels and renovations of old walls call for dry fixing (dry-hung cladding). What separates the two cases is how the wall carries load: a low wall with small units on a solid backing can be held by the bonded area, while a tall wall with large panels on a hollow backing needs brackets that carry each panel on its own. The order of the decision is fixed: wall height and backing first, panel size second, budget last. That order cannot be reversed, because the budget is an outcome of the first two and not a starting point. On the same wall, wet fixing saves the steel frame and hanger brackets, while dry fixing saves the cost of rework later. Buyers who ask us about Maple Red (G562 / G4562) open with which method is cheaper, when the useful opening question is how tall the wall is, how large the panel is and what the backing is made of. Without those three answers there is no basis for choosing.
Where exactly do dry fixing and wet fixing differ in physical terms?
The difference lies in how the load reaches the wall, not in the stone. In dry fixing a steel frame is anchored to the wall and each panel hangs on hanger brackets, leaving a cavity between panel and wall. Panel weight and wind load travel through the bracket into the frame and then into the structure, so every panel carries its own load and can be removed on its own. In wet fixing the panel is bonded to the backing with mortar or adhesive, and the whole bonded area shares the load. No gap remains, and one panel becomes part of a continuous skin with its neighbours. Everything else follows from that single difference: whether one panel can be replaced, whether a failure stays local, and where moisture can escape.
| Item | Dry fixing | Wet fixing |
|---|---|---|
| Load path | Each panel through its brackets into the steel frame | Shared across the full bonded area |
| Between panel and wall | Cavity | Mortar or adhesive, no gap |
| Single panel replaceable | Yes, each panel is independent | No, panels form one layer |
| Failure pattern | One panel at a time | A whole area peeling away |
Where should the height line be drawn, and why does a facade switch method?
The line is drawn by the extent of failure, not by appearance. Wet fixing fails as a sheet. Once the bond layer breaks down at one point and water enters the joints, freeze-thaw cycles or movement in the backing can push that whole area off at once, and dozens of panels come down rather than one. Dry fixing fails panel by panel. If one bracket gives trouble, only its panel is affected and the rest stay on the frame. That is the plain reason a facade above a certain height moves to dry fixing: a failure costs one panel. Where that height sits is a design decision based on local wind pressure, building height and the backing detail. We do not put a figure on it, and a stone supplier should not. What procurement can do is tell the designer early that the project is a facade, a tall building or a renovation, instead of raising it after the drawings are issued.
On the same wall, how much weight does each method carry?
The weight has to be counted layer by layer. A 30 mm panel at 2.7 t/m³ weighs 81 kg/㎡, and that layer is identical under either method. The difference sits behind the panel. A wet bed 20 mm thick at about 2.0 t/m³ adds roughly 40 kg/㎡, which brings the assembly to 121 kg/㎡. Dry fixing carries no mortar; it adds a steel frame and brackets instead, and that load lands on a small number of anchors. So on the same wall, the extra weight wet fixing carries is the 40 kg of mortar, not the stone. Dry fixing still adds steel, but the cavity gives moisture a way out, provided weep holes are left at the bottom, and that point returns in the next section. Whether the panel is 25 mm or 30 mm is a separate question, so everything here is calculated at 30 mm.
| Layer | Thickness | Weight per ㎡ |
|---|---|---|
| Granite panel | 30 mm | 81 kg/㎡ |
| Mortar bed, wet fixing | 20 mm | about 40 kg/㎡ |
| Wet fixing total (panel + mortar) | — | 121 kg/㎡ |
| Dry fixing (panel + frame and brackets) | 30 mm | panel 81 kg/㎡; ask the designer for frame and bracket weight per ㎡ |
How does each method fail, and what is one preventive step for each?
Wet fixing has three faults: hollowing, efflorescence and detachment. Hollowing means the bond layer never achieved full contact, and a tap sounds empty. Efflorescence is alkali from the mortar migrating to the surface with water and crystallising there; it is not a defect in the stone. Detachment is where hollowing ends up; efflorescence is only the mark the same water leaves on the face, and it does not by itself cause detachment. One step that works against all three: wet the backing, clean the panel back, and press the bond layer out to the edges instead of dabbing it at the corners. Dry fixing has three faults of its own: corroded hanger brackets, water standing in the cavity, and chipped slot edges. One step handles all three: specify stainless brackets, blow the stone dust out of the slot before the bracket goes in, leave weep holes at the bottom, and pull any panel with a chipped slot out of the batch, because a chip is where a crack starts.
What goes on the enquiry sheet so the supplier quotes by method?
Send a numbered list and ask for a line-by-line reply. Do not accept 'as usual'. Six items: one, the method, dry or wet. Two, panel thickness, and we hold 30 mm in stock. Three, the module size, length by width, taken from the drawing. Four, who fixes the bracket type or the mortar grade, the designer or the contractor, stated in writing. Five, whether the cavity is drained, which for dry fixing means weep holes at the bottom. Six, slots and sealing: cut in the factory or on site, and how many faces are sealed. Once those six answers are on paper, two quotations sit on the same basis and can be compared. Maple Red at 30 mm is held in stock, starts at 100 ㎡, ships in 5 days, and loads 346 ㎡ into a 20ft container.