Roof Coating Inspections

A new roof coating that is peeling back from the substrate during a roof coating inspection by rtoofsurveys.com

Why Roof Coatings Fail

Roof coatings are susceptible to failure from the day of installation and the reasons for the failure is not always obvious.

Our dedicated roofing surveyors are also Level 1 Coating Inspectors and can help identify the reasons why a roof coating has failed.

In more than 95% of cases, the reason for failure is not the coating itself that’s to blame.

During a roof coating inspection, our surveyor will look at the installation insructions for the coating system that has been applied and then carefully check as much information as is possible, to work out the reason for the failure.

Reasons for coating failure are many and varied. Sometimes, it’s a combination of circumstances that lead to the adhesion failure.

Our surveyors carry the tools that help identify the common reasons for failure, but occasionally, they will need to remove samples of a failed coating to conduct some more in-depth analysis.

Most often, roof coatings will fail during the installation phase, so the earlier we are involved, the better the likely outcome.

By identifying the cause of the failure, it allows contractors to rectify the problem and carry on with the coating installation.

 

What Happens During A Roof Coating Inspection?

Image shows a new roof coating splitting and debonding from the roof surface during a roof coating inspection by roofsurveys.com

When conducting a roof coating inspection, our surveyor will have first consulted the roof coating manufacturer’s technical data sheets to determine the conditions that the roof coating should be applied.

The surveyor will then inspect the areas where the coating is reported to have failed and if necessary, will remove samples for off-site analysis.

In most cases though, it will be possible to identify the most likely reason for the failure whilst on site.

When a roof coating fails to adhere, it is most likely to be due to installation errors or local environmental conditions causing surface contamination.

All coatings will specify the minimum film thickness that they are designed to be applied at. It’s a very important measure and so the surveyor will take hundreds of readings using a dry fim thickness gauge to determine that the correct film thickness has been applied.

The surveyor will also consider the surface to which the roof coating is being applied, the extent of preparation and cleaning.

Common Causes For Roof Coating Failure

Roof coating failures can be extremely frustrating, because it is not always obvious why a coating hasn’t fully adhered to a substrate.

The roof coating inspector’s job is really a process of elimination, so the roof coating inspection can be a prolonged process and you might not like the answer that you get.

Here are a few common reasons for roof coating adhesion failure:

Low Film Weight – coatings get their strength from the film weight. If it’s not applied to the correct minimum film thickness, it is likely to fail.

Insufficient Cleaning – If the surface of the roof is not clean, the roof coating will not properly adhere.

Improper / Insufficient Surface Preparation – All coatings require the surface they are being applied to to be preparaed to a certain standard. It is common for manufacturers to state a standard, for example, “ST3” in their specifications.

Environmental Conditions – As soon as a roof is cleaned, it can become soiled again within a matter of hours. Cleaning is not necessarily a one-off action and areas might need to be cleaned in isolation.

Incorrect Use Of Line Cleaners / Thinners – this is a common cause of failure. Roof coatings are made up from complex chemical recipes. Introduce something that is not compatible with the system and you have a potential for catastrophic coating failure.

Moisture Presence –  Most roof coatings require a bone-dry substrate, so even a small amount of dampness can cause a coating to peel back because it forms a layer between the substrate and the coating. Even so-called damp-tolerant roof coatings can be adversely affected if too much moisture is present. Who can define what is damp or wet? This one can really catch a trusting contractor out!

Temperature / Weather Conditions – Rain, fog, ice, high humidty and low temperatures all adversely affect roof coatings during installation.

Mechanical Damage – not all roof failures are actually classed as failures. If a roof is trafficked after a coating has been installed, care must be taken to ensure the coating surface is not damaged. Think scaffolding boards, heavy boots, solar panel equipment. Breaks in the coating can cause bigger issues later.

Incompatibe Substrate – Not all coatings adhere to all substrate types. Sometimes, this defect will not be noticed until a coating has been on the roof for some time – perhaps even severeal years. Our surveyors are very familiar with this issue and can diagnose the cause and a remedy.

As you can see, there’s a lot to consider when a roof coating fails.