Fibre Reinforced Facade Encyclopedia: Installation
Packing is the use of shims, packers, slotted holes and adjustable brackets to absorb the difference between where the structure actually is and where the facade needs to be. Every fixing lands on a surface built to a structural tolerance measured in tens of millimetres, and every panel has to finish within a facade tolerance measured in a few. Packing reconciles the two, and it works only within a range that has to be designed in advance rather than discovered on site.
A cast in situ concrete face can legitimately be 20 mm out of position. A facade joint can legitimately be 3 mm out of its nominal width. The bracket between them has to absorb the difference, in three axes, at every fixing.
At a glance
| Property | Typical value | Note |
|---|---|---|
| Purpose | Absorb structural deviation within facade tolerance | Three axes: in and out, up and down, along |
| Typical bracket adjustment | Plus or minus 15 to 30 mm | System dependent; confirm with the manufacturer |
| In and out adjustment | Shims or packers behind the bracket | The axis that sets the panel line |
| Vertical adjustment | Slotted holes or serrated plates | Set against the level datum |
| Horizontal adjustment | Slotted holes in the rail or bracket | Set against grid lines |
| Shim materials | Stainless steel, galvanized steel, engineered polymer | Non-compressible and non-corroding |
| Maximum shim stack | Commonly 10 to 15 mm total, manufacturer specific | Beyond this the fixing is re-engineered |
| Shim area | At least the full bearing area of the bracket | Point bearing on a partial shim is a failure mode |
| Fastener effect | Longer fastener, checked for bending and prying | Standoff increases the moment on the fixing |
Why packing is needed
Structures are built to structural tolerances and facades are seen at facade tolerances, and the two are an order of magnitude apart. A cast in situ concrete frame built entirely within the limits of AS 3610 and AS 3600 can present a slab edge 15 to 25 millimetres from its nominal position, with accumulation over height and out of plumb between floors. Nothing is wrong; that is what the tolerance permits. A facade, by contrast, is judged by eye against straight joints, and a 12 millimetre joint varying between 9 and 15 across an elevation is visible from the street.
How adjustment is provided in three axes
- In and out, perpendicular to the wall: shims or packers between bracket and structure, or a two-part bracket with a sliding connection. This sets the panel line and the cavity depth, and it is packed rather than slotted because the load path runs straight through it in bearing
- Vertical: slots in the bracket or rail, or serrated plates that lock at increments, set against the transferred level datum rather than the panel below
- Horizontal: slots in the rail or the panel bracket, set against the grid lines
- Rotational: a small amount of twist accommodation at the panel bracket, bringing a panel into plane where the structure behind it is not
Getting shims right
Shims are structural components. They sit in the direct load path between the panel and the building, in compression, for the life of the facade, often in a damp location behind the cladding where they can never be inspected. Treating them as offcuts is the most common site failure in this area.
The material must be non-compressible, which rules out plastic packers not rated for the purpose, timber, and anything that creeps under sustained load. It must be non-corroding and compatible with both bracket and structure, which in practice means stainless steel, hot dip galvanized steel matching the bracket, or an engineered structural polymer approved by the system manufacturer. It must cover the full bearing area of the bracket, because a partial shim converts uniform bearing into point bearing and can crush the bracket, spall the concrete or bend the plate. And the stack must be limited, commonly to the order of 10 to 15 millimetres, because a deep stack increases the standoff, the bending moment and the prying force on the fastener.
Beyond the permitted stack the answer is not more shims. It is a different bracket, a fixing re-engineered and checked by the facade engineer, or local correction of the structure. A shim stack built up to 40 millimetres by an installer trying to save a day is an unrecorded change to the structural design of the fixing. Shims should also be captive: slotted or horseshoe shims that locate around the fastener, with the fastener torqued to the specified value, keep the stack in place.
Packing in the other sense: protecting panels in transit
- Separation: every panel separated from its neighbour by soft, non-staining interleaving so faces never touch. Foam, corrugated board or non-woven fabric, not bare timber, and not polyethylene film directly on a cementitious face
- Edge and arris protection at every point where a strap, chain or frame bears, because arrises are the most vulnerable part of a thin shell panel
- Load spreading: soft bearers under every strap so restraint pressure is distributed rather than concentrated on a line of the face
- Correct bearer position: bearers under flat stacks at the designed support points and aligned vertically through the stack
- Frame capacity: A-frames and stillages engineered and rated for the load, not shop-built
- Weather and condensation: covered but ventilated, because a sealed wrap on a warm panel loaded into a cold container produces condensation and standing water leaves a permanent mineral mark
- Labelling: every panel labelled with its panel map number, visible without unpacking
What arrives damaged when this is done badly is predictable: chipped arrises and corners, strap marks and crush lines across the face, staining from timber, film or standing water, hairline cracking from panels supported at the wrong points, and a load that has to be entirely unpacked to find one panel. Panels should be inspected and damage recorded at the point of unloading, before they are accepted.
Standards and references
- AS 3610 and AS 3600, structural tolerances for formwork and concrete construction
- AS 5216 Design of post-installed and cast-in fastenings in concrete, including standoff and prying effects
- AS 4100 Steel structures and AS/NZS 4600 cold-formed steel structures, for bracket and rail design
- ISO 4463 and ISO 7976, measurement methods and tolerances for building
- National Transport Commission Load Restraint Guide, for restraint and load spreading on packed loads
- AS 3850 Prefabricated concrete elements, for handling, storage and support
- The system manufacturer’s installation manual for permitted adjustment range, shim material and maximum stack
Related terms
Questions specifiers ask
How much adjustment does a cladding bracket give?
Typically in the order of plus or minus 15 to 30 millimetres depending on the system, in three axes. Once a bracket runs out of range there is no site remedy, which is why the structure is surveyed before fabrication so the bracket schedule or panel line can be changed on paper.
What can shims be made of?
Non-compressible, non-corroding material compatible with the bracket and the structure: stainless steel, hot dip galvanized steel matching the bracket, or an engineered structural polymer approved by the system manufacturer. Not timber, not offcuts, and not general purpose plastic packers.
How thick can a shim stack be?
Commonly limited to around 10 to 15 millimetres in total, because a deep stack increases the standoff and therefore the bending and prying force on the fastener. Beyond the permitted stack the answer is a different bracket or a fixing re-engineered by the facade engineer, not more shims.
What is the difference between a slotted hole and a shim?
A slot allows movement during setting and is then clamped, relying on friction and correct torque. A shim transfers load in direct bearing and is more reliable in compression. A shim must cover the full bearing area, because a partial shim turns uniform bearing into point bearing.
How should panels be packed for delivery?
Faces separated by soft non-staining interleaving, edges and arrises protected at every bearing point, soft bearers under every strap, flat stack bearers at the designed support points and aligned vertically, frames rated for the load, covered but ventilated, and every panel labelled with its panel map number visible without unpacking.
Working out whether the bracket range absorbs what the structure has done? We survey, check the adjustment against the deviation and adjust the bracket schedule before fabrication. Talk to us about fixings
Reviewed by Richard Halvorsen, General Manager, ShapeShift Technologies. Last updated September 2026.