Roof Coating Overspray: Causes, Prevention and Remediation
Isolated gusts of wind on an apparently windless day can still occur randomly and without warning. This is how most occurrences of overspray occur.
Whilst professional contractors take extensive precautions to minimise the risk of overspray, no spray application process can completely eliminate the possibility of accidental contamination.
What is Overspray?
Unfortunately, small gusts of wind can result in the atomised product being lifted and carried for some distance as it leaves the spray gun.
Eventually, the product will fall to the ground or onto vheicles and structures, which will look like tiny dots of paint, feeling rough to the touch when the oversprayed coating cures.
Risks & Prevention
Therefore a collaborative approach is the best policy. Moving vehicles away from proximity of coating works is the simplest and most effective risk mitigation method.
However, a sudden gust of wind can easily carry an atomised coating significant distances. Contractors therefore tend to only spray apply roof coatings on days with little to no wind.
Rectify Early
If a vehicle is accidentally oversprayed, the contractor will probably be unaware. It is essential therefore, that if it happens, the contractor is notified immediately.
A quick response is the surest way to a quick and easy resolution.
The longer a coating is left to cure, the more difficult it is to remove.
Not All Overspray Incidents Are Caused by Weather
Whilst many overspray incidents are the result of unexpected wind conditions, some are caused by poor application practices.
For example, Liquasil was once asked to investigate an incident where a contractor was applying roof coating to the gable of a high industrial building. The working platform did not provide sufficient height to reach the upper sections of the wall safely. Rather than repositioning the access equipment or adopting an alternative method of application, the operative continued spraying whilst attempting to extend his reach beyond the normal working position.
As the coating was sprayed upwards, atomised product was carried beyond the edge of the building and deposited onto neighbouring property. In this instance, several camper vans located on an adjacent site required remedial cleaning as a result.
Incidents of this nature demonstrate the importance of suitable access equipment, experienced operatives and appropriate supervision. Professional contractors should always stop work and reassess the method of application if conditions or access arrangements prevent the coating from being applied safely and effectively.
Why Are Roof Coatings Sprayed If There Is An Overspray Risk?
Speed of application is the main reason that some contractors prefer spraying over any other type of application.
Industrial roofs are usually large and once cleaned, the installer will want to get the roof coated as quickly as possible before the cleaned surface becomes comtaminated again.
An experienced airless spray applicator can coat up to 1000 sq metres of roof in a day. It would take several days to coat the same area using brushes and rollers.
Although there is always a risk of overspray, these risks can be reduced by careful planning, so most will stop spraying if it starts to become windy or if wind gusting is occurring.
No contractor wants to see overspray. If it happens, if overspray happens, it’s almost always accidental.
What To Do If Your Vehicle Or Property Has Been Affected by Roof Coating Overspray
If overspray is suspected, the affected area, whether it’s on a car or property should be photographed before any cleaning attempts are made.
The contractor should be informed immediately so that the coating type can be identified and appropriate remedial advice obtained.
In many cases, overspray contamination on vehicles can be successfully removed by specialist vehicle detailers using clay bar treatment and polishing techniques.
Similar processes are used on glazing, cladding, solar panels and other solid surfaces.
Early intervention is often beneficial, as freshly deposited coatings are generally easier to remove than fully cured materials.
Attempting aggressive removal methods without first identifying the coating type may cause unnecessary damage to the vehicle finish.
Understanding the Scale of Loss
When overspray occurs, the appropriate remedy is usually the cost of returning the affected surface to its pre-incident condition.
In many cases this may involve specialist detailing, clay bar treatment, polishing or localised cleaning.
The presence of overspray does not necessarily indicate permanent damage to the vehicle.
The extent of remedial work required will depend upon the coating involved, the duration of exposure and the condition of the affected surface.
Why does overspray happen even on calm days?
On industrial buildings, spraying is often carried out several metres above ground level. Wind conditions at roof level can differ significantly from those experienced by people standing on the ground.
Buildings, parapet walls and surrounding structures can create turbulence that is not immediately obvious from ground level. As a result, isolated gusts can occur even when conditions appear calm.
People often assume “it wasn’t windy, therefore somebody must have been negligent.”
But that’s not how spray application works.
As a coating product goes through an airless prayer, atomised particles of the coating are created.
Because roofs are elevated structures, the wind conditions can be different to those on the ground, even when surrounded by parapet walls.
Isolated gusts often occur unexpectedly and can catch out even the most experienced sprayer.
Can roof coating overspray permanently damage a vehicle?
In many cases, no.
The presence of overspray does not necessarily indicate permanent damage to paintwork.
Many overspray incidents can be rectified by specialist detailing techniques.
The appropriate approach will depend upon the coating involved, the condition of the vehicle and the length of time the contamination has been present.
Liquasil products can usually be removed with standard detailing techniques even if left for some time, though we always recommend quick intervention to reduce the risk .
Can overspray affect surfaces other than vehicles?
Yes. Anything in proximity to a roof coating spray application can be affected because wind doesn’t discriminate.
Overspray occurs when the atomised coating particles are lifted by a wind gust. The speed of the gust determines how far it travels and also where it’s dropped.
We have seen instances where glazing, boats, motorhomes, signage, machinery and solar panels have been affected.
Overspray isn’t always noticeable by eye and will only be identified when a handis rubbed over the affected surface, which will feel rougher than normal.
The Importance of Proportionate Remediation
When assessing any overspray incident, the objective should be to return the affected surface to its pre-incident condition.
The presence of overspray does not automatically indicate permanent damage or the need for component replacement.
In many cases, specialist cleaning and detailing techniques can restore the affected surface without the need for more extensive remedial works.
The appropriate remedy will depend upon the coating involved, the extent of contamination and the condition of the affected asset prior to the incident.
What Happens If Overspray Is Not Noticed Until Long After It Occurs?
In some cases, overspray may not be discovered until weeks or months after a coating project has been completed. This can make it difficult to establish when the contamination occurred or whether it originated from a particular project.
Whilst delayed discovery does not necessarily prevent successful remediation, it may complicate investigations and increase the difficulty of determining responsibility. For this reason, affected surfaces should be inspected and reported as soon as contamination is suspected.
In many cases, specialist detailing techniques remain effective even where overspray has been present for some time.
Working Together to Resolve Overspray Incidents
No contractor wishes to overspray adjacent vehicles or property and most incidents can be resolved quickly when all parties communicate openly.
Prompt reporting, early inspection and proportionate remediation will usually produce the best outcome for everyone involved. Delays can increase costs, complicate investigations and make remediation more difficult than necessary.
The objective should always be to restore the affected surface to its pre-incident condition using the most appropriate and proportionate method available.
The guidance provided on this page is intended for general information only. The appropriate remediation method will depend upon the coating involved, the affected surface and the extent of contamination.