A Better Cut Edge Corrosion Treatment
Cut edge corrosion is the most common defect we see on metal roofs in our building surveying practice.
Most coatings marketed as cut edge corrosion treatments are overly complex and actually create a larger defect.
Liquasil has designed a simpler, cheaper, more effective and easier to apply system that actually works.
The system is called Flexlap. It comprises a marine grade epoxy primer that is overcoated with our unique, self-levelling, semi-gloss silicone coating.
In most cases, the joints in overlapping roof sheets at the mid-lap areas should not be sealed.
If the bottom most sheet at the mid-lap areas sare not affected by corrosion, why spend mopney preparing and coating it?
Liquasil’s Flexlap can provide huge cost savings against most other cut edge corrosion treatment systems, as well as significantly lower installation costs and a more resilient treatment.
Sometimes, sealing overlapping roof sheets might be necessary
There are occasions when it might be necessary to treat top and bottom sheets at the mid-laps, but in these cases, we do not recommend sealants, as they split easily, trap moisture and cause a latent defect.
Instead, we utilise our own HP Butyl Tape, a geo-textile faced, 20 year waterproofing tape that is far stronger than sealants.
This won’t necessarily stop underside corrosion, but it should help reduce the amount of moisture within the overlaps – but sealing laps is at your own risk, since water will always be present beneath, due to condensation and potential leaks from other areas in the roof.
But if you really prefer using a sealant
We won’t stop you. We have a product called Lapsil that’s made just for this purpose, but we don’t recommend its use because of the reasons already stated.
How To Seal Overlapping Roof Sheets
Strengthening The Mid-Lap Seal
When considering sealing overlapping metal roof sheets, the size of the gap between the upper and lower sheets needs to be considered.
When trafficked, the gap between overlapping roof sheets increases, but this effect can be reduced by stitching the sheets 100mm or so from the edge of the top sheet, using rivets or stitcher screws, prior to treating the cut edge corrosion.
Liquasil does not recommend the sealing of overlapping metal roof sheets in most cases. Where sealing is deemed necessary, we strongly recommend that additional fixings or stitchers are incorporated to reduce inter-sheet movement due to foot traffic. Sealing overlapping roof sheets may trap moisture or condensation, which can cause under-side corrosion of the roof sheets.
Cleaning The Flexlap System
Flexlap is a soft silicone coating that in common with other cut edge corrosion treatments, is susceptible to environmental dirt pickup.
The unique composition of Flexlap makes it easier to clean than other cut edge corrosion treatments.
All that is required is a weak solution of washing up liquid and water. Simply wash the surface with a sponge or mop, rinsing regularly to avoid smearing dirt over adjacent surfaces.
Sometimes, underside corrosion will be present at mid-laps and this can result in unsightly rust staining being noticable below the treated areas. This is not a defect and will usually wash off with soap and water.
We do not recommend that jet washing equipment is used to clean Flexlap installations.
All installations should be examined annually for signs of surface damage and, if noted, the affected area should be cleaned, dried thoroughly and touched up with Flexlap.
Whilst Flexlap does not support fungal growth, it is possible for algae and soil to settle on the surface.
Washing will usually remove this, and Liquasil can provide an anti-fungicidal wash to help delay any recurrance.
Please note that Flexlap can only be touched with Liquasil products. Other products are not likely to adhere to the treated surface.