Reducing corrosion at the cut edges of verge flashings

Galvanised, aluzinc and coated steel sheets may be suitable in different applications. However, there is no basis for treating one general description as a guarantee of resistance in every environment. The specification of the version being ordered must be known. Materials in contact with the flashing also remain important.

A cut edge differs from a factory-protected wide surface. It requires assessment in accordance with the recommendations for the given sheet. It should not be assumed that every metallic coating allows the condition of the edge to be ignored. Humidity conditions and the method of cutting are particularly important.

Appropriate shears or recommended cold-working tools are used for cutting verge flashings to size. An angle grinder with an abrasive disc may overheat the cut zone. In addition, hot particles may damage the nearby surface. A small shortening of the flashing should also be carried out using the correct method.

Metal residues from drilling and cutting should not lie on the coating. They may become trapped at the lap or under the folded edge. After installation, it is worth inspecting precisely such places. Cleaning only the wide, easily accessible part of the barge flashing is often insufficient.

Contamination should not be removed with a sharp tool that creates further scratches. The cleaning method is selected to suit the surface. If discolouration has appeared, it is worth first establishing its source. Deposits from a left-behind metal filing and damage to the sheet itself require distinction before choosing a repair.

Folds and bends help shape the edge of the flashing. They should not be treated as decoration that can be straightened at will. They should match the product drawing. Repeated adjustment of bends on site can worsen the appearance and condition of the coating.

Verge flashings must fit the actual roof cross-section. If they require strong pressing, the dimensions and the substrate must be checked. Only after clarifying the cause can a decision be made about correction. Adding screws in random places does not replace proper fitting.

The screw, washer and sheet should work together in accordance with the detail. Improper seating can leave a leak or deform a thin surface. It is worth checking the fixing points up close. A straight gable line viewed from the ground does not show all problems.

Joints between sections also require correct geometry to be maintained. Water should not be directed behind the flashing by an accidentally reversed lap. Ridge caps and gutter strips form its terminations. Their fit should be checked together with the verge flashing, not in separate, unrelated inspections.

Point damage is assessed according to the depth and type of coating. A solution intended for that surface is used for any touch-up. Random paint should not be spread over a large area. This can produce a difference in gloss without proper preparation of the repair site.

If the damage is extensive or the sheet has been significantly deformed, an assessment of the scope of replacement is needed. Not every defect can be reasonably removed cosmetically. It is worth keeping the material markings. They help in selecting the repair method and any new section of flashing.

The principles of careful cutting and cleaning also apply to chimney flashings and starter profiles. Unusual sheet metal flashings often have more bends, so they require a careful examination of the corners. A made-to-measure shape does not exempt the surface from protection during installation.

It is worth combining the inspection of barge flashings with a check of the entire roof. Attention should be paid to dirt, joints and changes in the appearance of the edge. Access to these places should be provided by a contractor with the proper safety equipment. An early assessment of damage allows repair to be determined before the problem covers a larger section.