Sheeting with netting and tarpaulin

Sheeting may be to keep the weather out (winter work, painting, moisture-sensitive work) or to catch falling material. The purpose determines whether netting is enough or tarpaulin is needed — and thus how much the wind load increases.

Netting partially closes and lets some of the wind pass through; sheeting closes (almost) completely and catches virtually all the wind. Sheeting gives the best weather protection, but loads the scaffold far more heavily — choose the least enclosed option that does the job.

Choose the least enclosed cladding that does the job — every extra degree of enclosure costs in anchoring.

The wind load depends on the degree of cladding. The scaffold calculator uses guideline cladding factors φ of approx. 0.35 for open, 0.50 for netting and 1.00 for sheeting. A sheeted scaffold can therefore catch several times as much wind as an open one — and the whole force must go down into the anchoring.

The wind-catching sail area is calculated in simplified form as the facade's plan area (L × H) times the coverage factor φ and a reduced shape factor ψ (indicatively ≈ 0.80 for open scaffolding): A_sejl = A_plan × φ × ψ. This is the area the wind load acts on.

You must NEVER hang netting or sheeting on a scaffold designed as open. Changed cladding requires the stability and anchor plan to be recalculated — typically with more and/or stronger anchors, because the horizontal force has increased.

Changed cladding = new calculation. Sheeting on an 'open' anchor pattern is a risk of overturning.

The indicative wind force in the calculator merely makes the order of magnitude visible. The actual design is carried out according to DS/EN 1991-1-4 DK NA with terrain category, peak velocity pressure and exposure, and the anchor capacity (R_anker) is taken from the supplier's data sheet. Leave the design calculation to the designers.

If work is to be done in frost or rain, winter sheeting may be required for the working environment. Remember that full winter sheeting is as impermeable as tarpaulin and therefore gives the highest wind load — plan anchors and any extra bracing accordingly.

After strong winds or storms, the sheeted scaffold must be given an extra inspection — this is where the forces have been greatest. Loose or frayed sheeting catches the wind unevenly and must be repaired or removed. If a storm is forecast beyond what the scaffold is designed for, it may be necessary to open or remove the sheeting.