Six ways to reduce the risk of wind damage to a roof

Wind action depends on the location, height and shape of the building and its surroundings. A roof in open terrain may experience different conditions from a similar building in dense development. The geometry of the roof slopes must also be included in the calculations. Do not copy a fixing pattern simply because a neighbour used the same profile.

Conditions at corners and edges differ from those in the middle of the roof. The design should identify the relevant zones and their requirements. This applies both to steel sheets and to sandwich panels. The manufacturer may provide tables, but these must be applied to the correct arrangement and loads.

Open canopies require a separate assessment because air also acts from below. Later addition of walls or screens can change the conditions. Such a change must be verified rather than treated as a neutral finish.

The covering transfers forces through the fasteners to the battens, purlins or other substrate. The rafters, trusses, walls and their connections then carry them further. A weak point in any one of these links can determine whether a failure occurs. A very strong screw in damaged timber will not provide predictable load-bearing capacity.

During renovation, the condition of the structure, corrosion and existing connections must be assessed. The lower weight of the new covering does not exempt you from this check. Dead load and wind suction act in different directions, so a lightweight roof requires correct anchoring. Safety must not rest on the weight of the material alone.

The documentation should state which elements remain and which require repair. Covering a weakened batten with new sheet metal does not improve its ability to hold the fastener.

The selection covers the thread type, length, drilling capacity and washer. A fastener for timber is not an arbitrary substitute for a screw into a steel purlin. The thickness of the element in which the fixing is made is also important. These details should appear in the schedule rather than remaining only an oral agreement by the crew.

The screw layout is determined by calculations and the covering manufacturer’s instructions. On roof sheets, load-spreading washers are often used on the upper rib. The flashing sheet may be fixed differently. One pattern should not be transferred between different products simply because both have a trapezoidal profile.

During installation, the tightening must be checked. A stripped thread or a damaged washer means a defective connection. The repair method should follow the system rather than leaving a loose screw in place.

Wind can act on an unprotected edge and gradually enlarge the damage. Flashings at the gables, eaves and ridge require proper support and fixing. Their role is not limited to appearance. A long strip screwed at a few random points can work loose and damage adjacent components.

Sheet overlaps and panel joints must be executed in accordance with the system’s direction and geometry. Stitching screws do not replace fixing to the structure. Sealant is also not a load-bearing element. A distinction must be made between a fixing that transfers forces and an element that only maintains the tightness of the joint.

At handover, it is worth inspecting the corners closely and comparing the workmanship with the drawing. From ground level, the colour of the flashing is often visible, but not the number, spacing and condition of its connections.

Photovoltaics, antennas and installations can increase loads or change the way they are transferred. Each bracket should have a defined substrate and fixing method. Colour or shape matching the covering alone does not confirm load capacity. Suction acting on modules positioned at the edges is particularly important.

For sandwich panels, it must be established whether the load reaches the structure or the facing in an approved system. Point loads should not be added to thin sheet independently. The design should also cover the tightness of openings and the possibility of thermal movement of components.

Space should be kept for service access. Checking the fixings will be difficult if the installation covers all connections and prevents inspection of critical roof edges.

Handover should confirm that the material, fasteners and fixing layout comply with the documentation. Damage to the coating, under-tightened elements and deformed edges should be checked. It is good practice to photograph concealed connections. Documentation makes it easier to assess later whether a visible change occurred during service.

After a strong gale it is worth commissioning a safe inspection, especially if new cracking can be heard or lifted flashings can be seen. The damaged roof should not be accessed without suitable protection. A loose component requires the cause to be repaired, not merely bent back to its previous position.

Regular inspection also covers corrosion and the ageing of seals. Wind exploits weaknesses that may have developed over many seasons. Keeping the connections in good order is part of roof protection, not an add-on to a one-off installation.