Sheeting, netting and what wind does to a scaffold

An unclad scaffold lets wind through. A sheeted one does not, and the loads it transmits into its ties and its base are materially different as a result. That is the single most consequential change anybody can make to a standing structure, and it is also one of the easiest to make without telling anyone.

It is a design change, not a finishing touch

Sheeting and debris netting are frequently treated as a site decision — the client wants containment, or the weather is poor, and material goes on. From the structure's point of view the loading assumption has changed, which means the tie pattern that was adequate may not be.

Netting and sheeting behave differently from each other, and both differ from bare tube. What each does to the loading is a design question answered by the designer against current guidance, not something to estimate on site. The operational rule that follows is simple: cladding a structure that was not designed clad is a referral, not an adaptation.

Partial cladding is its own problem

Sheeting a structure in sections — because the work moved, or material ran out — can produce loading patterns nobody considered, with wind acting on one part and passing through another. It looks like less of a change than full sheeting and is not necessarily.

In practice: the weekend that changed the structure

A client asks for sheeting on a Friday to contain dust over a weekend. The gang obliges, sensibly, at no charge. On Sunday night the wind gets up. On Monday the structure is inspected because somebody remembers the sheeting went on — and that inspection happens because one person made a connection, not because any process required it.

Two things were missing: a rule that cladding triggers a referral, and a record of the adaptation that would have made the change visible to anybody other than the gang that made it.

Common mistakes

• –Treating sheeting as a finishing item rather than a change to the loading
• –Cladding a structure that was not designed to be clad
• –Partial or phased sheeting, which can load unevenly
• –No record of when cladding went on, so nobody can connect it to later behaviour
• –Not prioritising clad structures after high winds
• –Removing sheeting locally to get materials in, and not reinstating it

Removing it matters too

Attention goes to putting cladding on. Taking it off, or having it torn off in weather, changes the loading back — and a structure tied for a clad condition is not in danger from becoming unclad, but a partially failed sheet flapping against a structure is a different matter entirely.

Damaged sheeting is also the most visible sign to anybody passing that something on the structure needs attention, which means it generates calls from clients and the public disproportionate to its actual severity. Dealing with it promptly is reputational as much as structural.

Getting this right

Clad structures deserve priority in any weather-triggered inspection, regardless of height — a small sheeted structure can behave less predictably than a tall bare one. And the decision to clad needs to reach the designer, which means recording it as an adaptation rather than treating it as a site task.

• –Treat cladding a structure not designed for it as a referral
• –Record when cladding goes on and comes off
• –Prioritise clad structures after high winds, whatever their height
• –Deal with damaged or partly detached sheeting promptly
• –Watch for partial or phased cladding, which loads unevenly
• –Reinstate cladding removed locally to get materials in

Where this connects: sheeting is also a commercial event

Cladding gets added for a client's benefit — containment, weather protection, appearance — and is frequently done without charge because it takes a gang an hour and the relationship matters. That is a reasonable commercial decision to make deliberately and a poor one to make by default, which is what happens when nobody records that it occurred.

The adaptation record is what makes it a decision. It puts the change in front of whoever prices work, it triggers the design question, and it establishes when the cladding went on — which matters if the structure later behaves unexpectedly in weather. One record, three purposes, and firms that keep it generally find the commercial one pays for the other two.

• –Record cladding as an adaptation, not as a site task
• –Let the record reach whoever prices variations
• –Decide deliberately whether to charge, rather than by default
• –Capture the date it went on, for weather questions later
• –Refer the design question before the material goes up
• –Record removal as well, so the loading history is complete