The Hidden Challenges of Metal Roof Cleaning
There’s a lot more to cleaning a metal roof than just jet washing the surface.
Depending on the size and location of the roof, it could be that the roof to be coated requires more than one clean, because surface contamination can occur even while the roof is being cleaned.
Also, because we control the weather and the environment, roof surfaces can be re-contaminated immediately after the metal roof has been cleaned.
Think about how often you see gulls and other birds nesting on industrial roofs. Then consider the proximity to trees, because sap can be carried in the wind and can soon re-contaminate the surface.
Cleaning is a constant battle on some roofs and if you’re about to start a roof coating project, it’s important that you consider the things that could soon eat into your profits, because cleaning takes time and costs money.
The Critical Role of Surface Degreasers
Despite thorough cleaning, metal roofs often face persistent issues such as surface contamination due to weather conditions or proximity to trees, major roads and even polluting neighbours.
Surface contamination can lead to adhesion problems if not addressed quickly and properly and if that happens, your costs could start to spiral.
Understanding these challenges is crucial for a successful roof coating project and we want to help you achieve that by showing you exactly what you need to do.
Understanding Post-Cleaning Challenges
Surface Contamination Insights
Residual Contaminants
Even after cleaning, some contaminants may remain and this will cause adhesion issues.
Insufficient Cleaning
Improper cleaning can lead to poor adhesion of protective coatings.
Degreaser May Be Needed
In some cases, a surface degreaser is necessary before applying coatings.
Multiple Cleaning Cycles
Certain areas may require more than one cleaning to ensure complete contaminant removal.
Environmental Factors
Weather conditions can contribute to rapid re-contamination of cleaned surfaces.
Incompatible Chemicals
Beware of chemicals. Use only those supplied or recommended by your coating manufacturer.
Daily Inspection
Larger roofs require daily inspection to ensure roof surfaces have not been re-contaminated.
Adhesion Testing
After cleaning and before coating, conduct several adhesion tests with your coating to avoid loss.
Common Questions About Adhesion and Cleaning
If your roof surface isn’t clean enough, you can expect adhesion issues that will not be covered under a product warranty.
Why is multiple cleaning necessary for some areas?
After roof cleaning, the surface remains susceptible to contamination from a number of sources.
Rainwater, pollen, tree sap, traffic film, pollution and other things can leave residue on the roof surface that can and often does, present a barrier between the substrate and your new coating.
What role does a surface degreaser play?
A surface degreaser helps remove oils and other residues that standard cleaning might miss, ensuring better adhesion of the coating. This is important when coating over primed surfaces that have been left more than 24 hours before overcoating.
How can I tell if my roof needs a degreaser?
Sometimes, you will see soiling on affected areas and these probably need re-cleaning. However, oil and grease is less visible and therefore the use of a surface degreaser is a sensible precaution.
Unfortunately, you can’t always tell when a surface degreaser is going to be necessary, but you will always discover it was when your new coating starts to peel away soon after installation.
What are the risks of inadequate cleaning?
Inadequate cleaning can lead to poor adhesion, resulting in coating failure and potential damage to the roof.
When using jet wash lances on metal roofs, use high pressure (about 4-600 psi) and a turbo lance. Hold the lance about 2 inches from the surfce, since this will also remove delaminating finishes and prior coatings.
Ultimately, if your cleaning is not sufficient, your new coating is likely to delaminate.
Liquasil’s team can easily identify coating failures that have occurred to surface contamination.
How often should a metal roof be cleaned?
Regular maintenance is recommended where surface contamination is a regular occurrence.
When a roof is to be coated, cleaning is an essential first step and cannot be left out.
What if Cleaning & Degreasing Fails?
Sometimes, if a coating will not properly adhere, then further testing will be necessary to determine the cause of the problem.
In some cases, an additional treatment might be required, for example, a bare galvanised surface will always require a mordant T-Wash solution treatment and a PVF coated surface might need an additional surface primer.
This is why thorough adhesion testing is necessary and why we insist that all contractors installing Liquasil products are trained by us.
Discover the Benefits of Liquasil Training
Liquasil’s products are only made available to contractors that have undergone our product training.
During the training, we discuss the reasons why adhesion failure can occur and back it up with images and videos so that attendees can avoid such problems on site.
Surface contamination is by far the biggest cause of adhesion failure of all coatings.
This means that cleaning and surface preparation is probably the most important thing that installers need to understand.
Liquasil training is free of charge at our premises in Solihull and depending on which systems are being demonstrated, the training session is only half a day.