A roof coating can add years of service to a commercial roof, but only when it goes on the right roof, over a dry surface, after proper repairs and preparation. Wet insulation, unsuitable substrates and unprepared surfaces can all cause coatings to fail early.
If you’re considering roof coating for a commercial building in East Lansing, including a retail or office building, apartment complex, church, warehouse or mixed-use property, understanding the process helps you compare proposals. Below is how a roof is evaluated for coating and how the system is applied, along with the difference between a coating warranty and how long the coating will actually last.
Want to discuss roof coating for your building? Call Armor Commercial Roofing at (517) 617-6953 to ask about assessment options.
Which Roofs Are Suitable for a Coating?
Not every roof should be coated. The existing roof, or substrate, has to be structurally sound, dry after necessary repairs and compatible with the coating chemistry. Substrates that commonly work well include:
- EPDM rubber: Coatings work well on aging EPDM with sound seams. A primer or special base coat is often needed for adhesion.
- TPO: Older TPO can be coated after thorough cleaning and adhesion testing. The surface often needs a specific primer.
- Modified bitumen: Granulated and smooth modified bitumen can accept compatible coatings once loose granules are removed and blisters are repaired.
- Built-up roofs (BUR): Some smooth or gravel-surfaced built-up roofs can be coated with an approved system. Gravel-surfaced roofs require additional preparation and a sound, suitable surface.
- Metal roofs: Coatings are very effective on metal when fasteners, seams and rust are treated first.
- Spray polyurethane foam (SPF): Foam roofs need a coating to protect them from UV damage, and recoating is part of normal SPF maintenance.
Some roofs are not good candidates:
- Roofs with widespread wet insulation
- Roofs with deck deterioration or structural problems
- Roofs where the membrane has shrunk, split or lost most of its attachment
- Roofs with severe, chronic ponding that has not been assessed and addressed
If your roof falls into one of those categories, a full roof replacement may be the better investment. A coating rated for ponding water does not eliminate the need to assess drainage and structural concerns.
Moisture Checks Before Anything Else
Coating over wet insulation can be an expensive mistake. Trapped water can break down insulation, corrode fasteners and decking, and contribute to blisters and loss of adhesion.
Before a coating is specified, moisture assessment may include:
- Infrared (thermal) scans: Under suitable conditions, these identify temperature patterns that may indicate wet insulation, which holds heat differently from dry areas.
- Moisture meters: These help assess suspect areas such as drains, seams and penetrations, using equipment suitable for the roof assembly.
- Core cuts: Small samples help confirm suspected moisture and reveal the roof layers and insulation type.
Wet sections should be identified, cut out and replaced with new insulation and compatible roofing before the coating goes down. If a large share of the roof is wet, coating may not be the right choice. The assessment findings should explain why.
Repairs Before Coating
A coating seals the roof surface, but it isn’t designed to bridge open seams, cover failed flashings or fill large holes on its own. Repairs come first, and they’re done with materials compatible with the coating system. Typical repairs include:
- Seams and laps: Open or weak seams are re-sealed and reinforced.
- Blisters and splits: Blisters are evaluated and repaired as appropriate, and splits are repaired with compatible membrane or reinforced coating details.
- Flashings: Loose or deteriorated flashings at walls, curbs and penetrations are re-secured or rebuilt.
- Metal roof fasteners: Backed-out or rusted fasteners are tightened or replaced, and fastener heads are sealed where required by the system.
- Rust: Rusted areas on metal roofs are cleaned and primed with a compatible rust-inhibiting primer.
- Drains and ponding areas: Clogged drains are cleared. Low areas may need drainage corrections before coating.
For roofs that need more than spot repairs, commercial roof repair may be necessary before coating.
Surface Preparation
Coatings only perform as well as the surface they’re bonded to. Dirt, chalking, oils and loose material all prevent adhesion. Preparation usually involves:
- Washing the roof: Dirt, algae, loose granules and chalk are removed using methods and pressures suitable for the existing roof.
- Cleaning with detergents or specialty cleaners: These address grease, exhaust residue or oxidation, which is common around restaurant vents and rooftop equipment.
- Letting the roof dry completely: Washing adds water to the surface, so enough drying time is needed before any coating is applied.
- Adhesion testing: Small test patches are applied and tested after curing to confirm the coating bonds to the specific roof surface.
- Priming where required: Primer selection depends on the substrate, coating manufacturer’s requirements and adhesion test results.
Skipping or rushing preparation can lead to peeling and delamination down the road.
Applying the Coating System
A roof coating is a system, not a single coat of paint. Depending on the roof and product requirements, application may include:
- Base coat at details: Seams, flashings, penetrations and transitions receive additional treatment, often with polyester reinforcing fabric embedded in a compatible coating. These are areas where roofs move and leak, so they need careful detailing.
- Field base coat: The main roof area receives its first coat at the specified thickness.
- Top coat: Another coat adds the required coverage and thickness. Some systems use contrasting colors to help check coverage visually.
- Thickness checks: Wet-film thickness gauges help crews check application thickness. Required dry-film thickness depends on the system and is important for performance and warranty eligibility.
Choosing the Right Coating Type
- Silicone: Holds up well to ponding water and UV exposure. A common choice for low-slope roofs, subject to the product’s approved uses and drainage assessment.
- Acrylic: Water-based, reflective and cost-effective. Best for roofs that drain well, since prolonged standing water can damage many acrylic coatings.
- Urethane: Tough and impact-resistant. A suitable system may be useful on roofs with foot traffic or equipment servicing.
Weather Windows in East Lansing
Michigan weather limits when coatings can go on. Most coatings need dry conditions, surface temperatures above the manufacturer’s minimum, and a suitable curing window without rain, heavy dew or freezing temperatures. In East Lansing, that usually means late spring through early fall. Scheduling should account for forecasts and morning dew so the coating cures properly.
Product Warranty vs. Expected Service Life: They’re Not the Same
This is where many building owners get confused, so it’s worth explaining clearly.
A product warranty is a written promise from the coating manufacturer covering specified defects for a set period. Separate contractor or system warranties may offer different coverage. Terms vary by product and project. Key points:
- The available warranty term may depend on the coating system, dry-film thickness, substrate and installation requirements.
- Some warranties cover materials only. Others include labor. A “no dollar limit” warranty still has defined coverage, conditions and exclusions.
- Exclusions may include damage from foot traffic, hail, building movement, ponding water or lack of maintenance, depending on the warranty.
- Periodic inspections and documented maintenance may be required to keep coverage valid.
Expected service life is how long the coating actually protects your roof in real conditions. It depends on:
- How well the moisture checks, repairs and preparation were done
- The coating type and thickness applied
- Drainage and ponding
- Foot traffic and rooftop equipment service
- UV exposure, freeze-thaw cycles and snow load
- Whether the roof is inspected and maintained
A coating can outlast its warranty when the roof is maintained, or fail before the warranty ends if it went over wet insulation or a poorly prepared surface. A long warranty on paper doesn’t make up for poor installation. Many coating systems can also be cleaned and recoated near the end of their service life, which adds years of protection without a tear-off.
Before work begins, review what the proposed warranty covers, what it excludes and what maintenance it requires. For more on how coatings protect commercial roofs, see our article on protective roof coating.
Why East Lansing Buildings Benefit from Roof Coatings
East Lansing’s commercial buildings include student housing and apartment complexes, offices and retail along the main corridors, churches, and older masonry buildings with built-up or modified bitumen roofs. Aging roofs that remain sound may be suitable candidates for coating.
Michigan’s freeze-thaw cycles, snow loads and summer UV exposure all wear down exposed roof membranes. A properly applied coating on a suitable roof:
- Protects weathered surfaces and properly repaired seams
- Reflects sunlight and can reduce summer cooling loads when a reflective system is used
- Adds a renewable protective layer that can often be recoated later
- Can reduce the cost, disruption and landfill waste associated with a full tear-off
- May allow tenants, residents and businesses to remain in the building during work, depending on site conditions
For related information in the Greater Lansing area, see our page on roof coating in Lansing, MI.
Get an Honest Roof Coating Assessment in East Lansing
If your commercial roof is aging but still sound, a coating may be a cost-effective way to extend its life after necessary repairs. A thorough assessment of moisture, adhesion and roof condition helps determine whether coating, restoration or replacement makes the most sense.
Call Armor Commercial Roofing at (517) 617-6953 to discuss roof coating in East Lansing, MI, and ask about an assessment and estimate.
Roof Coating FAQs
How long does a roof coating last?
It depends on the coating type, thickness, preparation and maintenance. Some systems have anticipated service lives of 10 to 20 years under suitable conditions and can be recoated to extend protection further. The specific product and roof condition matter.
Can you coat a roof that’s leaking?
Yes, but only after the leaks are found and repaired and any wet insulation is replaced. Coating over active leaks or wet areas can trap moisture and lead to failure.
Is a roof coating cheaper than a roof replacement?
Usually yes, often significantly, because there’s less tear-off, labor and disposal. It’s only a good value if the existing roof is a suitable candidate.
What’s the best coating for a roof with ponding water?
Silicone coatings are often suitable where water ponds, provided the product is approved for those conditions. Drainage problems still need assessment. Acrylics are generally better suited to roofs that drain well.
Will the coating disrupt my business or tenants?
Coating work often causes less disruption than a full tear-off, but the impact depends on repairs, access, odors and how the building is used. The project plan should address air intakes, occupied areas and any scheduling restrictions.
Does a longer warranty mean a better roof?
Not by itself. A warranty depends on the coating system, thickness and terms. Real performance depends on moisture checks, repairs, preparation and installation quality.