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ARMORTHANE PROTECTING YOUR WORLD

PROTECTING YOUR WORLD

ARMORTHANE PROTECTING YOUR WORLD

Asphalt Roof Coating:
Types, Coverage, Cost
& When Not to Use It

Fibered asphalt, emulsions, resaturants and aluminum: which asphalt roof coating goes on which low-slope roof, how much it takes, what it costs per year, and why it does not belong on shingles.
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$1.00–$2.50
Per sq ft installed for an asphalt (bitumen) roof coating
HomeGuide and The Roofing Brief, 2026
5–10 yrs
Typical service life of an asphalt emulsion roof coating
The Roofing Brief, 2026
4 gal
Per 100 sq ft for a fibered asphalt coating, 7–8 gal for a resaturant
Karnak 71 and 198 data
48 hrs
No standing water allowed this long after rain under cold-process coatings
Karnak data sheets

Asphalt roof coating is the black stuff in the 5-gallon pail: cut-back or emulsified asphalt, usually with fibers, brushed or squeegeed over built-up roofs, roll roofing, modified bitumen and old metal to keep the sun off the roof and buy a few more years. It is the cheapest coating on the shelf and it does a real job on the right roof. It also gets put on roofs where it can only make things worse, and it is often confused with the very different job of coating asphalt shingles. We manufacture spray polyurea and polyurethane systems, which sit at the other end of the price scale, so this guide is about when the cheap black coat is the right call and when it is not. It covers the types of asphalt roof coating and the ASTM standards behind them, which one goes on which roof, how much it takes, a cost-per-year comparison against white coatings, and how to put it down so it lasts.

Quick answer

An asphalt roof coating is a bitumen-based maintenance coat for low-slope asphalt roofs: built-up (BUR), modified bitumen, roll roofing and some metal. Fibered solvent asphalt coatings (ASTM D4479) go on at about 4 gallons per 100 sq ft; asphalt emulsions (ASTM D1227) at 3 to 4; resaturants that rejuvenate dried-out BUR at 7 to 8. Expect $1.00 to $2.50 per sq ft installed and 5 to 10 years of life. It needs a roof that drains, it absorbs heat because it is black, and it does not belong on asphalt shingles. For a reflective finish over asphalt, use an aluminum or white coating on top.

What's in this guide
  1. 1Types of asphalt roof coating
  2. 2Asphalt roof coating picker
  3. 3Asphalt coatings compared
  4. 4What about asphalt shingles?
  5. 5Cost per year calculator
  6. 6How to apply asphalt roof coating
  7. 7FAQ
Know what is in the pail

Types of asphalt roof coating and their standards

"Asphalt roof coating" covers four quite different products. The label will usually cite an ASTM standard, and that tells you more than the marketing copy.

ASTM D4479

Solvent-based asphalt coating

Asphalt cut back with solvent, fibered or not, brushed or sprayed. Type I uses asphalts that are self-healing, adhesive and ductile; Type II uses high-softening-point asphalt with lower ductility. Karnak's 71 fibered coating is a D4479 Type I, applied at 4 gallons per 100 sq ft from 40°F to 120°F, over smooth BUR, SBS modified bitumen, metal and roll roofing.

ASTM D1227

Asphalt emulsion coating

Asphalt dispersed in water with clay (Class 1) or chemical (Class 2) emulsifiers, with fibers or fillers (Types I and II) or without (Type III). Lower odor, water cleanup, and often used as a primer or base coat. D1227 covers built-up roofs and exposed surfaces with slopes of at least 4%, roughly 1/2 inch per foot.

Resaturant

Roof resaturant

A thin, oily asphalt that soaks into a dried-out BUR. Karnak describes its 198 as penetrating oils that rejuvenate old asphalt while leaving a surface layer that protects from UV and can bind new gravel. It goes on heavy, at 7 to 8 gallons per 100 sq ft.

ASTM D2824

Aluminum asphalt coating

Asphalt with aluminum flake for a silver, reflective face. It protects the asphalt from UV and reflects roughly 0.63 of sunlight when new. Full details are in our aluminum roof coating guide.

Asbestos in old coatingsBoth D1227 and D2824 still define a fibered-with-asbestos type, a leftover from older products. If you are tearing off or grinding an old black or silver roof coating, get a sample tested before you disturb it.
Picker

Asphalt roof coating picker

Choose the roof, its condition and what you want the coating to do. The picker returns the product type, the standard to look for on the label, the coverage rate, and anything that should stop you from coating at all.

Product match

Which asphalt roof coating does this roof need?

Rules from manufacturer data and standards cited on this page: D4479 fibered asphalt at 4 gal/100 sq ft, D1227 emulsions at 3–4 gal on slopes of at least 4% (about 1/2 in per foot), resaturant at 7–8 gal, D2824 aluminum at 1–1.5 gal, and no standing water 48 hours after rain.

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Coverage

    Side by side

    Asphalt roof coatings compared

    Click a heading to sort. Coverage and temperature limits come from representative manufacturer data; your product's data sheet governs.

    CoatingStandardCoverage (gal/100 sq ft)Min. application tempInitial solar reflectanceMain job
    Fibered solvent asphaltASTM D4479440°FDark, 0.05–0.20UV protection for BUR, mod bit, roll roofing, metal
    Asphalt emulsionASTM D12273–4Per data sheetDark, 0.05–0.20Low-odor coat or primer on sloped BUR
    Roof resaturantManufacturer spec7–840°FDark, 0.05–0.20Rejuvenate dried BUR, rebind gravel
    Fibered aluminum asphaltASTM D2824 Type III1–1.550°F0.63Reflective UV shield over asphalt
    White acrylic over asphaltASTM D60833 (two coats)40–50°F0.85Cool roof finish, needs compatible primer
    Sources: Karnak 71 (D4479 Type I, 4 gal, 40–120°F), 198 resaturant (7–8 gal, 40–120°F), 97 aluminum (1–1.5 gal, 50–120°F, 0.63 SR) and 529 acrylic (3 gal, 40°F and rising, 0.85 SR); ASTM D1227 scope; The Roofing Brief (emulsion 3–4 gal; dark roofs reflect 5–20%).
    Common mix-up

    Asphalt roof coating on shingles?

    Search "asphalt roof coating" and you will find people asking whether to coat their shingle roof. Those are different jobs. Asphalt roof coatings are made for low-slope asphalt membranes. Asphalt shingles are a steep-slope, water-shedding system that needs to breathe and dry between the laps.

    Brushing a black asphalt coating over shingles glues the tabs down, fills the gaps that let water drain, and adds nothing the granules were not already doing. Even purpose-made shingle coatings deserve caution: coating shingles can slow drying and trap moisture, and shingle manufacturers' warranties may be affected. If your shingles are curling, cupping or losing granules, the honest answer is usually repair or replacement. Our shingle roof coating page covers the narrow cases where a coating can make sense.

    Spot repairs are differentAsphalt roof cement under a lifted shingle or around a pipe boot is a normal repair. Coating the whole field of a shingle roof with black asphalt is not.
    Calculator

    Asphalt roof coating cost per year calculator

    Asphalt coatings win on price per square foot and lose on how often you have to redo them. This calculator spreads each option over the years you plan to own the building so you can compare like with like.

    Lifecycle

    What will this roof cost to keep coated?

    Applications = horizon / service life, rounded up. Low case uses the low price and long life, high case the high price and short life. Installed price and life ranges: asphalt $1.00–$2.50 and 5–10 yrs (HomeGuide, The Roofing Brief); acrylic $0.50–$3.00 and 7–20 yrs, silicone $1.50–$4.50 and 10–15 yrs (HomeGuide); polyurethane $1.50–$4.00 (HomeGuide) and 12–20 yrs (The Roofing Brief). Excludes repairs and inflation.

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    Applications
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    First application
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    Total over horizon
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    Per year (midpoint)

    Tired of recoating every few years?

    Talk to an applicator about a seamless membrane.

    When a flat asphalt roof keeps blistering, splitting or ponding, certified ArmorThane applicators can spray polyurea or foam roofing over a repaired, dry substrate. If a fresh asphalt or aluminum coat is all you need, they will say so.

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    Process

    How to apply asphalt roof coating so it lasts

    1. Find the water first

      Cold-process coatings belong only on roofs with positive drainage; Karnak's rule is no standing water 48 hours after rain stops. Probe soft spots and blisters. Coating over wet insulation seals the water in and the deck keeps rotting.

    2. Repair splits, blisters and flashings

      Cut out blisters, dry and patch them, and reinforce splits and flashing joints with roof cement and polyester fabric. Let the repairs set before coating over them.

    3. Clean the surface

      Sweep off loose gravel, dirt and debris. On gravel roofs, decide whether you are resaturating and regraveling or removing loose gravel for a coating; you cannot do both.

    4. Check weather and temperature

      Solvent asphalt coatings typically go on from 40°F to 120°F. Below 40°F, Karnak requires the surface to be free of moisture and ice. Emulsions must not get rained on before they set and should not freeze.

    5. Apply at the full rate

      Brush or squeegee fibered coatings at about 4 gallons per 100 sq ft, working them into the surface. A thin coat looks fine on day one and cracks the first summer.

    6. Add a reflective top if you want it cool

      Black asphalt runs hot; DOE notes conventional roofs can top 150°F. Once the base has cured, an aluminum coat or a compatible white elastomeric over a bleed-resistant primer drops surface temperature substantially. See our acrylic roof coating guide.

    SafetySolvent-based asphalt coatings are flammable and the vapors build up in enclosed spaces; follow the SDS and keep air intakes in mind on occupied buildings. Fall protection is required for roofing work 6 feet or more above a lower level under OSHA 1926.501.
    FAQ

    Asphalt roof coating questions

    What is asphalt roof coating used for?

    It is a maintenance coat for low-slope asphalt roofs: built-up roofing, modified bitumen, roll roofing and some metal roofs. It shields the asphalt from UV and weathering, fills minor surface cracks and extends the life of a roof that is still basically sound and dry.

    How long does asphalt roof coating last?

    The Roofing Brief puts asphalt emulsion coatings at 5 to 10 years with 3 to 7 year warranty terms. Real life depends on thickness, sun exposure and drainage. Plan on inspecting yearly and recoating when the surface starts to craze or chalk.

    How much does asphalt roof coating cost?

    HomeGuide and The Roofing Brief both put bitumen or asphalt emulsion coatings at about $1.00 to $2.50 per sq ft installed. Repairs, cleaning and any reflective topcoat are extra. See our roof coating cost guide for every coating type side by side.

    Can you put asphalt roof coating on shingles?

    We advise against it. Black asphalt coatings are made for low-slope membranes; on shingles they glue the tabs, interfere with drainage and drying, and may affect the shingle warranty. Spot repairs with roof cement are fine.

    What is the difference between fibered and non-fibered asphalt coating?

    Fibered coatings contain reinforcing fibers that build a thicker film and bridge small cracks, and they are applied heavier, around 4 gallons per 100 sq ft. Non-fibered coatings are thinner, spray more easily and are often used as primers or on smoother surfaces.

    What is a roof resaturant?

    A resaturant is an oily asphalt that soaks into a dried-out built-up roof to rejuvenate it, leaving a surface layer that blocks UV and can bind new gravel. It goes on heavy, about 7 to 8 gallons per 100 sq ft.

    Can you put asphalt coating on a metal roof?

    Fibered asphalt coatings are listed for metal roofs, and they protect old barn steel cheaply. They are black and hot, though, and you cannot easily paint over them later. On metal you want to keep looking good, see our metal roof paint guide.

    Can I put a white coating over an asphalt coating?

    Yes, after the asphalt has fully cured and with a primer the white coating's maker approves for asphalt substrates, because asphalt oils can bleed through and stain or soften a white topcoat. Aluminum coatings are the traditional reflective top for asphalt.

    AT
    Written by the ArmorThane technical team. We have manufactured polyurea, polyurethane and polyaspartic coatings and spray foam in Springfield, Missouri since 1989 and support certified applicators who restore and waterproof flat roofs. For the full range of roof systems, see our roof coating guide and roof waterproofing page. Updated October 2026.

    Sources

    1. ASTM D4479, asphalt roof coatings, asbestos-free: store.astm.org/d4479_d4479m-07r18.html
    2. ASTM D1227, emulsified asphalt used as a protective coating for roofing: store.astm.org/d1227-13.html
    3. ASTM D2824, aluminum-pigmented asphalt roof coatings: store.astm.org/d2824_d2824m-18.html
    4. Karnak, 71 fibered asphalt roof coating: karnakcorp.com/product/71-fibered-asphalt-roof-coating
    5. Karnak, 198 asphalt roof resaturant: karnakcorp.com/product/198-asphalt-roof-resaturant
    6. Karnak, 97 fibered aluminum and 529 acrylic data: karnakcorp.com/product/97-fibered-aluminum-roof-coating
    7. HomeGuide, roof coating cost by type (2026): homeguide.com/costs/roof-coating-or-sealing-cost
    8. The Roofing Brief, roof coating types and cost (2026): theroofingbrief.com/roof-coating-types-and-cost
    9. The Roofing Brief, solar reflectance reference (2026): theroofingbrief.com/roofing-solar-reflectance-sri-reference-2026
    10. Wikipedia, roof coating (coating asphalt shingles): en.wikipedia.org/wiki/Roof_coating
    11. U.S. Department of Energy, cool roofs: energy.gov/energysaver/cool-roofs
    12. OSHA 29 CFR 1926.501, fall protection: osha.gov 1926.501

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