How Do You Measure Accurately for Aluminium Cladding?
Measure from the as-built structure, not the architectural drawings. This is the single most important rule for cladding measurement, and the one most often broken. Drawings tell you what the building was supposed to be. The site survey tells you what it actually is - and those two things are rarely the same.
Accurate measurement is the difference between a smooth installation and weeks of rework. Panels ordered to drawing dimensions arrive on site and do not fit. Brackets cannot reach. Joints do not line up. The subframe design assumed a plumb slab edge that is 15mm out. Every one of these problems traces back to the same root cause: someone ordered materials without surveying the structure first.
What Is the Golden Rule?
Never order panels based on drawings alone. Always site-survey the as-built structure before finalising panel sizes and quantities.
Drawings are a starting point for estimating scope and planning the facade layout. They are not a reliable basis for ordering materials. The structure as built will deviate from the design - the question is how much, and where.
What Should You Measure on Site?
A thorough cladding site survey covers four things:
- Overall facade dimensions. Height and width per elevation, measured at the structure - not at the render line or any applied finish. Measure at multiple points across each elevation, because the structure will not be perfectly consistent.
- Opening locations. Windows, doors, louvres, penetrations. Measure from structural references (slab edges, columns), not from finishes that may not be in their final position yet. Record the size of each opening and its position relative to the structural grid.
- Structural deviations from design. Check slab edges for straightness, column positions against the grid, and floor levels for consistency. A slab edge that bows 10mm over a 20-metre run is normal in concrete construction - but if you do not know about it, your panel layout will not account for it.
- Maximum deviation from plumb and level. This determines how much bracket adjustment is needed in the subframe. A structure that is 20mm out of plumb over three storeys requires a subframe design that can accommodate that - and that information must come from measured data, not assumptions.
What Tools Should You Use?
- Laser level - the primary tool for checking plumb and level across the facade. Essential for any project beyond a single storey.
- Total station - for large facades where cumulative error from tape measurements becomes significant. Worth the setup time on any building over four or five storeys.
- Tape measure - for verification and local measurements. Use a quality steel tape, not a fabric tape.
- Plumb bob - a simple check for column and slab edge plumb. Useful as a quick verification alongside the laser.
Take multiple measurements at each level. Record the worst-case deviations, not just the average. Photograph your reference points and mark structural set-out clearly so the installation team can locate the same datum points later.
What Manufacturing Tolerances Should You Account For?
Panels are manufactured to tolerances, not to exact dimensions. Your joint design and subframe layout need to accommodate these.
element13 (solid aluminium panels):
| Dimension | Tolerance |
|---|---|
| Width (>1200mm and up to 1500mm) | +/-2.0mm |
| Length (>3000mm) | +/-4.0mm |
| Thickness | +/-0.18mm |
interloQ (interlocking rainscreen): Manufactured to AS/NZS 1866:1997 extrusion tolerances, which govern dimensional accuracy for aluminium extrusion profiles.
Joint widths should be designed to accommodate three things together: panel manufacturing tolerances, installation tolerances (the accuracy of your subframe and fixing), and thermal movement.
How Much Does Aluminium Move with Temperature?
Aluminium expands at 23 micrometres per metre per degree Kelvin. That number matters on every project.
A 6-metre panel in a 40 degree Celsius temperature range - say 5 degrees on a winter night to 45 degrees on a summer-exposed surface - moves about 5.5mm in length. Joints and fixings must accommodate this. For interloQ, fixing slots are elongated specifically to allow thermal movement - do not over-tighten fixings through slotted holes.
This is not a theoretical concern. Panels that are fixed rigidly with no allowance for thermal movement will buckle, distort, or pop fixings. The damage is visible, structural, and expensive to fix.
What Are the Common Measurement Mistakes?
Three mistakes account for most measurement-related problems on facade projects:
- Measuring from unfinished surfaces. Render, internal cladding, and other finishes that have not been applied yet will change the dimension. Measure from the structure, not from a surface that is going to move.
- Not accounting for floor-to-floor variation. Concrete structures commonly vary in floor-to-floor height by 5-15mm. A panel layout designed for a consistent 3,200mm floor height will not fit a structure where the actual heights range from 3,190mm to 3,210mm.
- Ordering based on a single measurement point. One measurement per elevation is not enough. The structure varies - slab edges bow, columns shift, floor levels differ. Measure at multiple points and design for the worst case.
What Documentation Should Come from the Survey?
A good site survey produces a marked-up set of drawings showing actual dimensions, deviations from design, and datum references. This becomes the basis for the panel schedule, the subframe design, and the installation set-out. Without it, everyone downstream is guessing.
Valmond & Gibson’s technical documentation includes fixing and joint details that specify required clearances and tolerances for interloQ and element13 systems. These details are designed around realistic site conditions - but they rely on accurate measurement data to work properly.
Measure twice, survey the structure, and never trust the drawings on their own. The time spent on a proper site survey is a fraction of the cost of panels that do not fit.
Need technical documentation or measurement guidance for your project? Get in touch with our team.
Related Reading
- Managing Facade Tolerances on Construction Projects
- Thermal Expansion in Aluminium Facades: A Design Guide
- Subframe Design for Aluminium Rainscreen Cladding
- Panel Sizes and Module Planning for Aluminium Cladding
Last updated: 4 April 2026