One of the questions that comes up with aging commercial roofs is whether the entire roof needs to be replaced or whether a roof coating can extend the life of the existing system.

It’s a reasonable question. Roof replacement is a major construction project, so naturally, building owners want to know whether the existing roof can remain in place.

Sometimes it can.

Sometimes it can’t.

The important thing to understand is that a roof coating isn’t a magic blanket that makes everything underneath it new again. If the existing roofing system is in suitable condition, coating may be an option. If there are widespread problems underneath the surface, covering them doesn’t make those problems disappear.

Roofs, unfortunately, are not impressed by optimism.

Start With What’s Under the Surface

A commercial roof can look rough without necessarily being structurally unsound. The opposite can also happen. A roof might look reasonably normal from above while moisture has been working its way into the system underneath.

That’s why the decision shouldn’t be based entirely on appearance.

The existing membrane needs to be examined for cracks, punctures, open seams, deterioration and areas where materials have separated. Flashing around walls, vents, pipes and rooftop equipment also needs attention.

Then there’s the question of moisture.

If water has entered the roofing assembly and saturated large areas of insulation, applying a coating over the surface doesn’t remove that moisture.

At that point, the problem is underneath the coating.

A Little Damage and a Lot of Damage Are Different Things

Commercial roofs take abuse.

HVAC technicians walk across them. Maintenance crews move equipment around. Storms send branches and debris across the surface. Years of sunlight and temperature changes gradually affect roofing materials.

Some amount of repair work on an older commercial roof isn’t unusual.

A few localized areas may be repairable as part of preparing the roof for a coating. Damaged sections can sometimes be addressed while the remainder of the roofing system remains serviceable.

Widespread failure is different.

If seams are opening throughout the roof, large portions of membrane are deteriorating or significant areas contain trapped moisture, restoration may no longer address the real problem.

There comes a point when fixing everything necessary to make a roof suitable for coating starts looking suspiciously like rebuilding the roof.

Drainage Matters More Than People Think

Commercial roofs are often called flat roofs, but they shouldn’t actually function like swimming pools.

Low-slope roofs are designed to move water toward drains, scuppers or gutters.

After a Louisiana thunderstorm, some water may remain temporarily. Persistent ponding in the same areas, however, can indicate drainage or slope problems.

That matters when evaluating a roof for coating.

Different coating systems have different tolerances for standing water, but a coating shouldn’t automatically be treated as the solution to a drainage problem.

If water keeps collecting in one spot, figuring out why is generally more useful than simply giving the puddle a new floor.

The Existing Roof Material Matters

Not every commercial roof is built the same way.

There are metal roofs, modified bitumen systems, built-up roofing, TPO, PVC, EPDM and other materials.

Coating products are also different.

The coating has to be compatible with the existing roof surface, and proper preparation may include cleaning, repairs and primers.

Adhesion is critical.

If the coating doesn’t bond properly to the roof, it doesn’t matter how carefully everything else was planned.

That’s why surface preparation is such an important part of coating work.

A roof covered with dirt, oils, biological growth or deteriorated material usually needs more than somebody opening a bucket and finding a roller.

Old Repairs Can Complicate Things

Commercial roofs tend to develop a history.

A leak happened eight years ago, so somebody patched it.

Another leak appeared three years later, and somebody used a different material.

Then somebody else fixed something around an HVAC unit.

Eventually, the roof becomes a little archaeological record of every maintenance decision made since the building opened.

Those previous repairs need to be evaluated.

Some materials may work with a proposed coating system. Others may require additional preparation or removal.

The goal is to create a stable, compatible surface before the coating is applied.

Age Isn’t the Only Question

People often ask how old a roof can be before coating is no longer practical.

There isn’t one universal number.

A roof’s condition depends on much more than the date it was installed.

• Maintenance history matters.
• Storm exposure matters.
• Drainage matters.
• Installation quality matters.
• Foot traffic matters.

Two commercial roofs installed in the same year can age very differently.

One may remain dry and structurally stable while another has experienced repeated leaks and repairs.

The birthday of the roof is useful information, but it doesn’t tell the entire story.

Louisiana Weather Has Opinions

Around Slidell and Southeast Louisiana, commercial roofs experience plenty of weather.

• Heat.
• Humidity.
• Heavy rain.
• Tropical systems.

Occasional cold weather just to keep everybody guessing.

All of that affects roofing materials over time.

Weather also matters when applying coatings. Many products require specific temperature ranges and dry conditions during installation and curing.

Anyone familiar with Louisiana weather understands the comedy involved in scheduling something that requires guaranteed dry conditions.

Forecasts are helpful.

So is flexibility.

When Does Replacement Make More Sense?

Replacement becomes more likely when the underlying roofing system has widespread deterioration, saturated insulation, structural concerns or extensive membrane failure.

At that point, removing or rebuilding portions of the roof allows those underlying problems to be addressed directly.

A coating is most useful when there is still a viable roofing system worth preserving.

That’s really the key distinction.

The question isn’t simply whether a roof can physically be coated.

Almost anything can be painted if somebody is determined enough.

The better question is whether the existing roof provides an appropriate foundation for a coating system.

That requires looking at membrane condition, moisture, drainage, previous repairs, structural stability and material compatibility.

Sometimes the answer is coating.

Sometimes the answer is replacement.

The roof usually provides enough evidence to make the distinction.

It just needs somebody to actually listen to what it’s saying.