Roof Coatings After Hail: When a Coating Is and Isn't the Answer
By Blake Snow, experienced roof consultant
Roof coatings have become a common option for large low-slope roofs. A properly selected and applied coating system can extend the life of a sound roof, and on big buildings it can avoid the cost and disruption of a full tear-off. After a hailstorm, owners are often offered a coating as a quick fix. Sometimes that's a reasonable choice. Sometimes it covers up problems that will cost far more later.
This article explains how a roof consultant thinks about coatings after hail, and the questions to answer before anyone sprays anything.
A coating is not a repair for a failed assembly
A coating goes on top of the existing roof. It doesn't fix what's underneath. If hail fractured the cover board, crushed the insulation, or let water into the assembly, coating over it traps those problems. Wet insulation loses insulating value, can damage the deck and fasteners over time, and can cause the new coating to blister or fail. That's why the condition under the surface matters more than how the top looks.
Questions to answer first
- Is the insulation dry? An infrared moisture survey, confirmed with core cuts, can map wet areas. Wet insulation generally needs to be removed and replaced before any coating.
- How damaged is the membrane or surface? Fractures, punctures and damaged seams need proper repair first. Widespread damage may mean the roof isn't a coating candidate at all.
- Is the substrate compatible? Different coatings work over different roof types. Adhesion and compatibility should be confirmed, often with adhesion tests.
- What about drainage? Ponding water is hard on many coatings. Drainage issues should be understood before choosing a system.
- What do the warranties say? Existing roof warranties and the coating manufacturer's requirements both matter.
- What does the claim or scope say? If there's an open insurance claim, the scope of the covered repair should be settled before decisions are made that change the roof.
When a coating can be the answer
A coating may be a good fit when:
- The roof assembly is substantially dry, confirmed by testing
- Hail damage is limited and can be properly repaired before coating
- The existing roof surface is compatible with the coating and passes adhesion testing
- Drainage is acceptable or will be corrected
- The coating system and warranty fit the owner's plans for the building
In those cases, a coating can be a cost-effective way to restore and extend the roof's service life over large areas.
When a coating isn't the answer
A coating is usually the wrong choice when:
- Significant areas of insulation are wet
- The cover board or insulation is crushed or fractured over large areas
- The membrane has widespread fractures or is too deteriorated to repair properly
- The deck or fasteners are compromised
- The coating would be used to hide damage rather than restore a sound roof
Coating a roof in that condition may look fine for a while, but the underlying problems usually come back, and they can be harder and more expensive to deal with later.
Coatings and hail claims
From the roof side, coatings raise a few practical issues on a hail claim. Coating a roof before it's been documented can make it harder to evaluate the hail damage afterward. A prior coating can also affect how hail damage presents and how a roof is evaluated after a later storm. And whether a coating is an appropriate repair for a given loss is a scope question that should be grounded in the condition of the roof, not just the cost.
A consultant's role is to document the roof's condition, test where needed, and lay out the options (repair, restore with a coating, recover or replace) section by section, with the reasoning written out. See our forensic roof consulting and roof systems pages.
Timing matters
When a coating is applied matters too. Coating soon after a storm, before the roof has been documented and any claim scope has been settled, can make the hail damage harder to evaluate later and can complicate the claim. Coating in poor weather can also hurt adhesion and curing; most coating systems have temperature, humidity and dew point limits for application. And coating a roof with wet insulation in the hope that it will dry out is rarely a good bet. Moisture trapped under a coating usually has nowhere to go.
The better sequence on most large roofs is to document the roof, test for moisture, settle the scope of any covered repairs, make the repairs properly, and then decide whether a coating fits the roof that's left.
Questions to ask a coating contractor
- Has the roof been tested for moisture, and can I see the results and locations?
- Which hail damage will be repaired before coating, and how?
- Was adhesion testing done on this roof surface?
- Which coating system is proposed, and what thickness and number of coats?
- What warranty is offered, by whom, and what does it require?
- How will ponding areas, seams, flashings and penetrations be treated?
Clear answers to those questions are a good sign. Vague answers, or a proposal to coat without testing, are a reason to slow down and get an independent look at the roof first.
Maintenance after coating
A coating is not a set-and-forget roof. Most coating systems need periodic inspection, cleaning of drains and gutters, and attention to damaged or worn areas. Many warranties depend on it. Owners should budget for that maintenance and keep records, which will also help if the roof is ever evaluated after a future storm.
Large buildings
On big roofs and multi-building portfolios, the answer is often mixed: some sections are good coating candidates, some need repair first, and some need replacement. A roof inventory and moisture survey make it possible to plan that intelligently instead of applying one answer to every roof.
For more on how coating systems are installed, our sister company has an overview of roof coatings.
General information only, not legal or coverage advice.