How does wind load affect support spacing for sandwich panel walls?

The structural designer determines wind pressure and suction for each zone. Suction pulls the cladding away from its supports, placing demand on the fixings. A panel may carry the load over the proposed span while the fastener or the material it is anchored into governs the capacity of the connection.

A panel spanning between two supports behaves differently from one that runs continuously over an intermediate support. Span tables distinguish between single-span and continuous arrangements and specify the bearing conditions. Read the column for the actual arrangement. Another column may show a longer span that the proposed wall cannot achieve.

Check the bearing width and the geometry of each connection as well as the distance between support centrelines. A rail can be in the right position yet provide too narrow a bearing face. Before choosing replacement cladding, measure the support faces and spacing on the existing frame.

Match the table to the core material, panel thickness, both facings, their profiles and the fixing type. Values for a 0.6 mm steel facing cannot simply be applied to a 0.5 mm version. Changing the facing can affect load capacity, stiffness and local behaviour at the support.

Read the table notes to see whether the figures are characteristic loads, design values or another quantity, and which criteria apply. Put the loads and tabulated values on the same basis before comparing them. If the basis is unclear, ask the structural designer to interpret the data.

Load capacity and serviceability are separate checks. A panel may carry the specified load yet deflect more than the wall detail allows. Excessive deflection can affect the façade’s appearance, strain joints and interfere with adjacent windows or doors.

The colour of the outer facing affects how much it heats up in sunlight. Span tables may therefore specify colour groups and length limits. If the finish changes from light to dark, check that the proposed panel length and support arrangement still fall within the permitted range.

Windows and loading doors interrupt the panel and support layout. They need suitable framing and fixings around their edges. Even when wind loading would permit the longest span in the table, the opening detail may require closer supports.

The scope of the wall’s fire resistance classification may impose a further limit. An assembly with a specified EI rating may require a particular span, panel orientation and fixing method. The chosen layout must meet these conditions as well as the wind load and deflection requirements.

For illustration, a uniform pressure of 0.8 kN/m² acting over 6 m² produces a total force of 4.8 kN. Multiplying pressure by area shows how much force the panel has to transfer. To determine support spacing or screw quantities, the designer must also check the panel and its connections under the applicable design conditions.

Increasing the span increases the loaded area at a given panel width and changes the bending stresses and deflection. Adding screws in proportion to the extra area cannot account for those effects. Where supports are already in place, the assessment may point to a different panel or alterations to the supporting rails.

Show the wind zones, supports, panel direction and fixing pattern on the drawing. Mark local changes around corners and openings. Before installation, inspect the frame and check its alignment. Straighten or correct misaligned rails before fitting the panels.

Keep the drawings and design information after installation. A new loading door, an additional storey or a change to the façade may require the cladding to be checked again. Recording the support spacing gives the designer a reliable starting point for assessing alterations later.