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Skyland Infrastructures
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Façade Engineering

Structural design of curtain walls, unitised systems and feature façades, including wind loading, movement and performance specification.

A façade is the only part of a building that has to be simultaneously weathertight, structurally adequate under peak wind, thermally efficient, tolerant of the frame moving beneath it, and beautiful. It is also usually the last package to be procured and the first to be value-engineered, which is why it produces a disproportionate share of building defects.

Loads first

Every façade decision descends from the wind pressure, so we derive it properly. That means the correct terrain category for the actual site rather than the plot, the right internal pressure coefficient for the building’s permeability, correct local pressure factors at corners and parapets where the peaks are two or three times the field value, and — for tall or unusual buildings — a proper reading of wind tunnel results rather than a headline number.

Getting this stage right is where the money is. A corner zone pressure applied uniformly across an elevation adds glass thickness to eight thousand square metres that only needed it on two hundred.

Movement is the hard part

The frame beneath a façade is not static. A concrete core shortens under sustained load and continues to creep for years; perimeter columns shorten at a different rate; slabs deflect under live load and again under long-term creep; and the whole assembly expands and contracts with temperature at a rate the frame does not share.

Our movement strategy sets out, for every joint in the envelope, what movement it must accommodate and in which direction — and then we check that the specified gasket and bracket can actually do it at the end of their service life, not on the day of installation.

Specification and verification

We write performance specifications rather than prescriptive ones wherever possible, so that specialist contractors can bring their own systems and compete properly. The specification defines the test regime: air infiltration, static and dynamic water penetration, structural performance under design and 1.5× design wind, and seismic racking where relevant.

Then we witness the mock-up tests. A performance specification nobody verifies is a wish.

Questions

What clients ask before appointing us

Isn't the façade contractor responsible for the façade design?
For the system itself, usually yes. But the contractor is appointed after the tender, prices against your specification, and has a commercial interest in the loosest interpretation of it. Façade engineering on the client side sets the performance requirements that make those bids comparable, and checks that the winner meets them.
When is wind tunnel testing worth the cost?
For buildings above roughly 150 m, for unusual plan shapes, for sites with significant interference from neighbouring towers, and wherever a code-derived pressure would drive the glazing thickness to an uneconomic value. On a tall tower the testing frequently pays for itself in reduced glass and bracket cost.
Do you handle movement between the façade and the frame?
That is most of the discipline. Frame shortening, differential creep between core and columns, slab deflection under live load, and thermal movement all have to be absorbed by the bracket and the joint. Most façade failures we are called to investigate are movement failures, not strength failures.

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