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ARMORTHANE PROTECTING YOUR WORLD

PROTECTING YOUR WORLD

ARMORTHANE PROTECTING YOUR WORLD

Spray-On Roof
Coating: Rigs, Mils
& Warranties

Which roof coatings can be sprayed, how many gallons each warranty tier takes, which pump, hose and tip to run, and when a roof shouldn’t be coated. With three calculators for contractors and owners.
Roof Coating Quotes

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Tell us the roof type, size and condition. We'll connect you with an ArmorThane-certified applicator for a spray polyurea, spray foam or coating quote with the mils and warranty in writing.

  • Commercial, metal and spray foam roofs
  • Polyurea roof liners and SPF roofing
  • Mils, primer and warranty on the quote
  • Contractors: ask about spray rigs and training
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Step 1 of 3
16.04 mils
Wet film from 1 gal per 100 sq ft
1,604 ÷ 100
22 · 29 · 36
Dry mils for 10 · 15 · 20-yr silicone
Mule-Hide spec
.029–.035
Typical silicone tip orifice
Gaco spray guide
48 h
Ponding limit before you can't coat
NRCA definition

A spray on roof coating is the fastest way to put a seamless membrane on a commercial roof, and the fastest way to put one on the cars in the parking lot if the wind picks up. We manufacture sprayed roofing systems (polyurea roof liners like ArmorSeal 100 AL and ArmorFoam Roof 200 closed-cell spray foam), build spray rigs and train the crews who run them. This page covers the spray-applied side of roof coatings that most guides skip: which coatings can be sprayed, the mil math behind warranty tiers, the pump, hose and tip you need, and when a roof shouldn't be coated at all.

Quick answer

Acrylic, silicone and polyurethane roof coatings are sprayed with a heavy-duty airless rig; polyurea and spray foam need a heated plural-component proportioner. Coverage is all mil math: 1 gallon per 100 sq ft lays down about 16 wet mils, and dry mils = wet mils × volume solids. Silicone warranties typically step from 10 to 15 to 20 years at about 22, 29 and 36 dry mils (1.5, 2.0 and 2.5 gal per 100 sq ft). Installed costs run about $0.65–$1.75 per sq ft for acrylic, $1.50–$2.50 for silicone and $2–$5 for polyurethane (Angi, 2026), more for full commercial systems. Don't spray over wet insulation, ponding water or in wind, and asphalt shingle manufacturers' trade association advises against coating shingle roofs. Calculate your gallons.

What's in this guide
  1. 1Which roof coatings can be sprayed
  2. 2Gallons, mils & warranty calculator
  3. 3Sprayer, hose & tip selector
  4. 4Reading a spray tip code
  5. 5Can this roof be spray coated? (checklist)
  6. 6Spray technique and overspray control
  7. 7Spray coatings on asphalt shingles
  8. 8Spray roof coating cost
  9. 9Spray-on roof coating FAQ
Chemistry & standards

Which roof coatings can be sprayed

Almost every liquid roof coating can be sprayed. The difference is the equipment and how much material actually becomes membrane. Click a column to sort.

CoatingStandardVolume solidsSpray equipmentInstalled $/sq ftWatch out for
Acrylic (waterborne)ASTM D6083≥50% (spec minimum)Airless, single component$0.65–$1.75Ponding water; can't apply near freezing or before rain
SiliconeASTM D6694 (over SPF)≈90–96%High-pressure airless (≈6,000+ psi)$1.50–$2.50Hard to recoat with anything but silicone; slippery when wet
Polyurethane (aromatic base + aliphatic top)ASTM D6947 (over SPF)Product-specificAirless or plural component$2–$5Humidity during cure; aromatic bases need a UV top coat
Polyurea / hybridManufacturer specs100% (e.g. ArmorSeal 100 AL)Heated plural-component proportionerQuoteRecoat windows; aromatic grades need a UV top coat
Spray foam + coatingASTM C1029 Type III foamFoam + topcoatPlural-component foam rig$5–$10 (system)Wind, overspray and the coating's mils over foam
Standards: IIBEC summary of ASTM D6083; MaTest summary of ASTM D6694; ASTM D6947 and C1029 via ASTM and Professional Roofing. Solids: GacoFlex S20 (95%) and manufacturer data. Installed costs: Angi (Aug 2026) for coatings; West Roofing Systems for SPF + silicone systems.

Acrylics are the budget workhorse: waterborne, reflective, easy to clean up, and the D6083 spec requires at least 50% volume solids, so half of what you spray evaporates. Silicones are 90%+ solids, shrug off ponding better than acrylic and dominate restoration warranties, but almost nothing but more silicone sticks to them later. Polyurethanes are the toughest of the single-component group for foot traffic and hail. Polyurea is in a different class: 100% solids, gels in seconds, builds full thickness in a pass, and is what we spray on roofs that see abuse. Our ArmorSeal 100 AL is a 1:1, solvent-free polyurea roofing liner. For a non-spray overview, see our roof coating guide, silicone roof coating and spray foam roofing pages.

Tool 1 of 3

Gallons, mils & warranty calculator

Warranties are written in dry mils, but you buy and spray wet gallons. This converts between them the way manufacturers do: wet mils = dry mils ÷ volume solids, and gallons per 100 sq ft = wet mils ÷ 16.04. Check: Mule-Hide's 1.5 gal per 100 sq ft is 24 wet mils, which leaves about 22 dry at roughly 92% solids.

Roof coating calculator

How much coating for the warranty you want

Warranty tiers are silicone examples (Mule-Hide, GAF Unisil). Always use your manufacturer's spec.

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Wet mils to spray
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Gal per 100 sq ft
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Total gallons
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5-gal pails · 55-gal drums

Tool 2 of 3

Sprayer, hose & tip selector

Roof coatings are thick, and hoses on a roof are long. The pump has to deliver enough pressure at the gun after a few hundred feet of hose, and enough flow to feed the tip. Pick the coating and your setup.

Rig selector

What equipment the job needs

Specs from Graco, Gaco and Pittsburgh Spray Equipment published guidance. Example rigs, not endorsements.

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    Decode it

    Reading a spray tip code

    Graco-style airless tips use a three-digit code. Double the first digit for the fan width in inches at 12 inches from the surface; the last two digits are the orifice in thousandths of an inch. A 517 sprays a 10-inch fan through a .017 orifice, fine for paint and far too small for roof coatings. A 631 sprays a 12-inch fan through .031 and, per Gaco's guide, flows about 1.03 gallons per minute.

    TipFan width @ 12 inOrificeFlow (silicone, Gaco)Typical use
    62712 in.027≈0.74 GPMDetail work, thinner elastomerics
    62912 in.029≈0.90 GPMSilicone, acrylic field coats
    63112 in.031≈1.03 GPMSilicone field coats
    63512 in.035—Heavy-bodied silicones, high build
    Graco: tip code system and .025–.035+ for elastomerics. Gaco silicone spray guide: .029–.035 orifices and flow rates. Worn tips spray a wider orifice and a narrower fan; replace them on schedule or your mils drift.
    Tool 3 of 3

    Can this roof be spray coated?

    A coating restores a sound roof. It doesn't fix a failing one. Tick everything that's true today; any red item stops the job until it's fixed.

    Go / no-go checklist

    Is the roof (and the day) ready?

    Conditions from the Mule-Hide silicone spec, NRCA, SPFA and ARMA.

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    On the roof

    Spray technique and overspray control

    1. Clean, repair and prime

      Power-wash, let it dry, repair seams, flashings and blisters, and prime where the manufacturer requires it. Coatings follow the substrate: a weak spot under the membrane becomes a weak spot in it.

    2. Detail first

      Brush or spray reinforced detail coats at seams, penetrations, drains and curbs before the field coat.

    3. Hold distance and overlap

      Gaco's guide: gun 12–18 inches from the surface, 50% overlap on each pass. Cross-hatch the second pass at 90° for even mils.

    4. Measure as you go

      Use a wet-mil gauge every few hundred square feet. Gallons on the roof ÷ area is the honest check at the end of the day.

    5. Control the overspray

      Mule-Hide doesn't recommend spraying "if any wind is occurring." SPFA notes that around 15 mph makes controlled spraying difficult and calls for a typical 25 ft setback from other workers; Gaco ropes off 150 ft. Cover intakes, shut down rooftop units and move the cars.

    Plural-component rigs are a different jobPolyurea and spray foam react inside the gun. They're sprayed from a heated proportioner (for example, Graco's Reactor 2 E-XP2: 3,500 psi, 2 GPM, 1:1, heating to 190°F through up to 310 ft of heated hose) and need a trained operator, respirator protection and isocyanate handling procedures. That's exactly what our spray rigs and applicator training are built around.
    Read this before you spray a house

    Spray coatings on asphalt shingles

    "Spray on roof coating for asphalt shingles" is a popular search, and the honest answer is cautious. The Asphalt Roofing Manufacturers Association (ARMA) "strongly advises against" field-applied coatings and rejuvenators on installed shingles, citing curling or cupping, granule loss, trapped moisture and possible effects on fire, algae and impact ratings. Coating can also affect the shingle manufacturer's warranty.

    Two different products get lumped together here:

    • Shingle rejuvenators such as Roof Maxx are a sprayed soy-based penetrant, not a membrane. Roof Maxx claims up to 5 years per treatment and up to 3 treatments, at about $1.75 per sq ft.
    • Shingle coatings such as Armor Garage's acrylic shingle coating ($379 per 5-gal pail covering about 1,250 sq ft in two coats, 5-year warranty) form a film over the shingles.

    We don't recommend coating a pitched shingle roof that's near the end of its life. Re-roof it. If you're considering either product, read the shingle manufacturer's warranty first. Our shingle roof coating page covers this in more depth. Low-slope commercial roofs, metal roofs and spray foam roofs are where spray coatings earn their keep.

    2026 pricing

    Spray roof coating cost

    SystemInstalled $/sq ftSource
    Acrylic coating$0.65–$1.75Angi, Aug 2026
    Silicone coating$1.50–$2.50Angi, Aug 2026
    Liquid rubber$1.75–$3.50Angi, Aug 2026
    Polyurethane coating$2–$5Angi, Aug 2026
    Commercial silicone restoration system$3.50–$7.00West Roofing Systems
    Spray foam + silicone$5–$10West Roofing Systems
    Angi lists materials alone at $0.15–$2.50/sq ft and labor at $0.50–$3. Restoration systems include cleaning, repairs, primer and warranty-grade mils; the coating-only figures don't.

    Use the calculator above to price the material for your warranty tier; the difference between a 10-year and a 20-year silicone spec is about one extra gallon per 100 sq ft. On a 10,000 sq ft roof, that's roughly 100 gallons.

    For roofing contractors

    Spray roofs with polyurea and foam. We'll build your rig.

    ArmorThane manufactures sprayed roofing systems (ArmorSeal polyurea liners and ArmorFoam Roof 200 closed-cell foam), builds mobile spray rigs and trains your crew on plural-component equipment. Not a franchise: no franchise fee, no royalties.

    See spray rigsBecome an applicator

    Building owners: get a roof coating quote →

    Straight answers

    Spray-on roof coating FAQ

    Can you spray roof coating with an airless sprayer?

    Yes. Acrylic, silicone and single-component urethane roof coatings are sprayed with heavy-duty airless rigs. Silicone needs high pressure; Gaco calls for at least 5,950 psi output. Polyurea and spray foam need a heated plural-component proportioner instead.

    What size spray tip do I need for roof coating?

    Typically .025–.035 inch orifices for elastomeric coatings (Graco) and .029–.035 for silicone (Gaco), such as a 629 or 631 tip. Check the coating manufacturer's spray guide.

    How many gallons of roof coating per 100 square feet?

    It depends on the target dry mils and the coating's volume solids. One gallon per 100 sq ft is about 16 wet mils. Silicone specs commonly call for 1.5, 2.0 and 2.5 gallons per 100 sq ft for 10, 15 and 20-year warranties; granulated surfaces need more.

    How thick should a roof coating be for a 10, 15 or 20-year warranty?

    In Mule-Hide's silicone specification, about 22, 29 and 36 dry mils respectively. Other manufacturers and chemistries differ, so use the specific warranty spec.

    Is spray-on roof coating good for asphalt shingles?

    Generally no. The Asphalt Roofing Manufacturers Association strongly advises against field-applied coatings and rejuvenators on installed shingles because of curling, granule loss, trapped moisture and possible effects on fire and impact ratings. Spray coatings are best suited to low-slope commercial, metal and spray foam roofs.

    What's the difference between Roof Maxx and a roof coating?

    Roof Maxx is a sprayed soy-based rejuvenator that soaks into asphalt shingles; it doesn't form a membrane. A roof coating forms a continuous waterproof film over the roof.

    How much does spray-on roof coating cost?

    In 2026, about $0.65–$1.75 per sq ft for acrylic, $1.50–$2.50 for silicone and $2–$5 for polyurethane installed (Angi). Full commercial silicone restoration systems run about $3.50–$7.00, and spray foam plus silicone $5–$10 per sq ft.

    Can you spray roof coating in the wind?

    It's not recommended. Overspray travels, and at around 15 mph controlled spraying becomes difficult. Some manufacturers advise against spraying in any wind. Protect cars, intakes and people downwind.

    Can you coat a roof with ponding water or wet insulation?

    No. Wet insulation must be removed and replaced, and ponding (water remaining 48 hours after rain) should be corrected with drainage or tapered insulation first. Coatings restore sound roofs; they don't fix failing ones.

    Which spray roof coating lasts longest?

    Life depends mostly on thickness and the warranty spec rather than chemistry alone. Silicone and polyurethane systems are commonly warranted 10–20 years at higher mils; spray foam systems with a maintained topcoat can last longer with periodic recoating.

    AT
    Written by the ArmorThane technical team. We manufacture spray polyurea and spray foam roofing systems, build spray rigs and train applicators across North America. Updated October 2026.

    Sources

    1. IIBEC, ASTM D6083 explained: iibec.org
    2. MaTest Labs, ASTM D6694 summary: matestlabs.com
    3. ASTM D6947 (moisture-cured polyurethane coatings over SPF): store.astm.org
    4. GEI, wet film formulae: geionline.com
    5. Mule-Hide 100% silicone roof coating guide specification: buildsite.com (PDF)
    6. GAF, installing silicone commercial roof coatings: gaf.com
    7. GacoFlex S20 silicone product data sheet: gaco.com (PDF)
    8. Gaco silicone coating spray guide: gaco.com (PDF)
    9. Graco GMAX II 7900 Roof Rig: graco.com
    10. Graco roofing equipment catalog: graco.com (PDF)
    11. Graco, choosing and understanding airless spray tips: graco.com
    12. Pittsburgh Spray Equipment, spraying elastomerics and roof coatings: pittsburghsprayequip.com
    13. Graco Reactor 2 E-XP2: graco.com
    14. SPFA, site preparation: spraypolyurethane.org
    15. Professional Roofing, SPF standards: professionalroofing.net
    16. Professional Roofing, ponding water: professionalroofing.net
    17. Angi, roof coating cost per square foot (Aug 2026): angi.com
    18. West Roofing Systems, spray-on roofing systems: westroofingsystems.com
    19. ARMA, coating of asphalt shingles after installation: asphaltroofing.org
    20. Roof Maxx, soybean oil vs roof coatings: roofmaxx.com
    21. Armor Garage, shingle roof coating: armorgarage.com

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