Polyaspartic vs epoxy garage floor coatings

Both are two-part coatings. A resin is mixed with a hardener, and a chemical reaction turns the liquid into a hard film.^{[3, 6]}

Epoxy is usually a bisphenol A or F resin cured with an amine hardener.^{[4, 8]} Covestro, which makes coating raw materials, says most common floor coatings are based on aromatic binders, which it calls the yellowing kind.^[17] Makers say standard epoxies can yellow or chalk in UV light, and clear epoxy data sheets say interior use only.^{[4, 7, 8]}

Polyaspartic is made by reacting an aspartic ester resin with an aliphatic polyisocyanate. Covestro lists its aliphatic hardeners for non-yellowing topcoats.^{[4, 17]} Laticrete, for one, sells its polyaspartic as an aliphatic polyurea. That is why quotes mix the words "polyurea" and "polyaspartic".^{[1, 4, 27]} A polyurea base coat is not always the same product as the polyaspartic topcoat over it.^{[11, 12]}

A coated garage floor is built in layers. There may be a primer. Then comes a colored base coat, with vinyl flake broadcast into it while wet until it will not take any more. Once the base sets, the loose flake is scraped off and a clear topcoat seals it.^{[10, 25]} Each layer can be a different chemistry.^{[10- to 12]}

• Epoxy only. An epoxy base and a clear epoxy top. It usually has the lowest material cost, but clear epoxy is labeled for interior use, so the floor can yellow where sun reaches it.^{[4, 7, 8]}
• Epoxy base with a polyaspartic topcoat, often called a hybrid. One maker's version is an epoxy primer, an epoxy base with flake, and a polyaspartic top, about 60 mils thick in all. With a fast-cure epoxy base, the same idea can be done in one day.^{[10, 24]}
• Polyurea base with a polyaspartic topcoat. This is what some installers sell as a "polyaspartic floor". Penntek, for example, sells a polyurea/polyurethane base coat and a polyaspartic topcoat for flake floors, and says its topcoat is not meant to go straight onto concrete.^{[11, 12, 15, 16]}
• Full polyaspartic. Polyaspartic in every coat, for example a fast-cure colored base and a slower clear top. One maker's version is over 50 mils thick. On a damp slab, makers call for a moisture vapor barrier primer first.^{[25, 28]}

A coating maker explains the reasoning: epoxy body coats for build, adhesion and chemical resistance, with polyaspartic on top for UV stability and easy cleaning.^{[4, 10]}

Thickness is measured in mils. A mil is a thousandth of an inch, so a 60 mil floor is about 1/16 inch.^[10] In one maker's data sheets, a 100% solids epoxy base goes on at about 8 to 30 mils wet per coat. With no water or solvent to evaporate, it stays close to that once dry.^{[6, 10, 24]} Polyaspartic coats are thinner, about 4 to 16 wet mils. Laticrete caps a coat at 10 wet mils and Westcoat at 6 dry mils, because thicker coats can turn milky or soften.^{[1, 3, 19]} A water-based DIY epoxy kit dries to about 3 to 3.5 mils per coat.^[21]

Return to service is when you can walk or drive on the floor. Full cure comes later and takes days for both chemistries.^{[6, 7, 19, 20]}

• Polyaspartic: foot traffic in about 2 to 6 hours on faster grades, and vehicles often at 24 hours.^{[1- to 3]}
• Some polyaspartics take longer. One maker's extra-slow grade needs 3 days before heavy traffic, and Westcoat says 72 hours before tires on its polyaspartic.^{[3, 19]}
• Pro epoxy: heavy traffic at about 2 to 3 days at 72 to 77°F. One product needs 4 to 5 days at 50°F (10°C). One epoxy primer gives 72 hours before wheels.^{[6- to 8]}
• Water-based DIY epoxy kit: 3 days before you drive on it.^[21]
• Full cure: about 4 to 5 days for polyaspartic and 5 to 7 days for epoxy at room temperature. In the cold it takes longer: about 7 days for one polyaspartic and 10 days for one epoxy at 50°F (10°C).^{[6, 7, 19, 20]}

With a hybrid, the base sets the schedule. A 100% solids epoxy base needs 5 to 14 hours before the next coat, depending on its cure speed, and about 2 days before heavy traffic.^[6] A fast-cure epoxy base is what makes a one-day hybrid possible.^[24]

Some installers give longer waits. An Edmonton-area installer tells customers to wait 5 to 7 days before parking on its epoxy floors. A Vancouver-area installer says one recent garage job waited 5 days before parking, and stresses that this was one project, not a universal cure time.^{[9, 13]}

Cold slows every coating, and dry air slows polyaspartic. Data sheet times assume about 70 to 77°F, and Simiron says to expect longer traffic times for its polyaspartic when it is cooler than 72°F or the humidity is under 50% during cure.^{[1, 3, 7]} Ask your installer for the day you can park, in writing, based on the products and the weather on install day.

Epoxy can yellow in sunlight. Data sheets say epoxy may darken or yellow, and that clear epoxy is for interior use unless a UV-resistant coat goes on top.^{[7, 8]} Rust-Oleum's EpoxyShield DIY kit page says indoor use only.^[29]

In a hybrid, the polyaspartic top protects the look, but epoxy the flake does not cover can still yellow. Simiron's epoxy-base system guides warn that spots not covered by chip will discolor.^{[10, 24]} One installer says yellowing is most noticeable on white and grey solid colors.^[5]

Polyaspartic holds up well in lab UV tests. In one maker's test, gloss went from 92 to 95 down to 87 to 89 after 1,000 hours under UV lamps.^[3] The ASTM UV test standard says results from different test machines should not be compared unless they have been shown to match. Read a lab number as a direction, not a forecast of years.^[30]

UV resistant is not UV proof. Westcoat says long sun exposure may still change its polyaspartic's look and performance, and Elite Crete labels one of its polyaspartics not for exterior concrete.^{[18, 19]} If your driveway apron or patio gets coated too, check that the data sheet allows exterior use.^[18]

In a closed garage it matters less. M&M Floors, which sells both, lists a garage that gets no direct sun as a reason to choose epoxy.^[5] The exposure to watch, installers say, is sun through an open door or a garage with a lot of natural light.^{[5, 27]}

Abrasion is usually reported with the Taber test, ASTM D4060. In the data sheets we read, abrasive wheels run over a coated panel for 1,000 cycles, and the weight lost is recorded. Less loss means better wear resistance.^{[3, 6, 31]}

From the same maker, the polyaspartic lost 30 mg and the epoxy lost 50 mg.^{[3, 6]} Across brands the numbers overlap. The polyaspartics we read lost 30 to 65 mg, and the pro epoxies 50 to about 65 mg.^{[3, 6, 7, 12, 19, 20, 23]} ASTM warns that fillers and friction can skew comparisons between coatings, and names epoxies as an example.^[31] So polyaspartic often wears better, but it depends on the product.^{[3, 4, 6]}

Chemical resistance is mixed. In Simiron's charts for its own polyaspartic and epoxy, the polyaspartic rated better on solvents such as MEK, xylene and isopropyl alcohol, and on brake fluid. The epoxy rated better on 10% nitric acid, 10% sulfuric acid, 50% sodium hydroxide and mineral spirits. Both rated excellent on motor oil, transmission fluid, bleach and E85 fuel.^{[3, 6]}

Battery acid needs care. CAA-Quebec, a consumer organisation, says polyaspartic is more vulnerable to battery acid. One maker's residential warranty excludes damage from brake fluid and battery acid.^{[32, 33]} Whatever you choose, wipe spills up quickly.^[28]

Hot-tire pickup is when warm tires stain a coating, or in bad cases pull it off. Tires contain plasticizers, softeners that leach out as the rubber heats up and move into the coating. Rubber mats and the weatherstripping on a garage door can do it too.^[26] Euclid Chemical says epoxy and urethane coatings are less likely to mark than acrylic cure-and-seal products, but it is still possible. Simiron's data sheets say tire marking may occur on both its polyaspartic and its epoxy.^{[3, 6, 26]} Some kit pages promise no hot tire pickup. We would not count on any coating being immune.^{[26, 29]}

Two things help. Let the floor cure before you drive on it, since Westcoat warns that early tire traffic can cause staining. And if you are worried, Simiron suggests parking on a small sheet of metal or plexiglass.^{[19, 28]}

Cracks and joints. Installers and CAA-Quebec say polyaspartic and polyurea flex more than rigid epoxy.^{[27, 32]} Data sheets for both kinds of system still warn that moving joints and shrinkage cracks can show through the coating. Prep patches cracks, and joints built to move should be kept open through the coating, not buried under it.^{[10, 28]}

Pot life is how long a mixed batch stays workable. Standard polyaspartic grades often give about 10 to 25 minutes, slow grades give longer, and heat and humidity shorten it.^{[1, 2, 19, 22, 23, 34]} In one maker's chart, its fast grade at 72°F gives 25 minutes in dry air but only 14 minutes at 80% humidity. Its extra-slow grade gives up to 2 hours in dry air.^[3]

Crews have to keep a wet edge. Simiron says the next batch should meet the last within 5 to 10 minutes, or tie-in lines can show.^[3] CAA-Quebec says two or more experienced workers are ideally needed, because polyaspartic cures in under 30 minutes.^[32] Coats rolled too thick can turn hazy or milky.^{[1, 3]}

Many polyaspartic data sheets say professional use only.^{[1, 19, 22, 23]} The hardener is an isocyanate, and makers call for respirators and good ventilation during the install. Keep people and pets out of the garage while it goes down.^{[1, 17, 19, 28]}

To be fair, pro epoxy is not much easier. A 100% solids epoxy also gives only about 12 to 40 minutes.^{[6, 8]} Longer pot lives of 1 to 2 hours or more belong to thinner water-based and solvent-based epoxies.^{[7, 21]}

DIY kits have a place, such as a budget floor in a closed garage. Know what you are buying.

• Rust-Oleum's water-based EpoxyShield kit dries to about 3 to 3.5 mils per coat, must be used within 1 to 2 hours of mixing, needs 60 to 85°F (15 to 29°C), and takes 3 days before you drive on it.^[21]
• Rust-Oleum's EpoxyShield kit page says indoor use only.^[29]
• Kit prep is a mild citric acid etch, and the moisture check is a taped plastic sheet. Pro installation guides call for grinding or shot blasting the concrete, and set moisture limits by ASTM tests.^{[3, 21, 25, 28]}
• "Polycuramine" is Rust-Oleum's own name, not a polyaspartic label. Its RockSolid data sheet lists the resin as a blend of epoxy, urethane and polyurea, with a 45 to 60 minute pot life and vehicles in 24 to 36 hours, depending on temperature.^[35]
• Its product page says drive on in 24 hours. We went with the data sheet.^{[35, 36]}
• CAA-Quebec notes that without a professional installer, the manufacturer's warranty is often limited to one year.^[32]

If you find a polyaspartic sold to homeowners, read its data sheet for pot life, coat thickness and temperature range before you buy.

Many polyaspartics and most epoxies need about 50°F (10°C) or warmer.^{[7, 8, 19, 23]} Some grades of each go colder. Simiron rates both its polyaspartic and its fast-cure epoxy down to 35°F (2°C), and Penntek's winter-grade polyaspartic topcoat is rated 30 to 60°F.^{[3, 6, 12]} Laticrete lists low temperature cure at 25°F (-4°C) for one of its polyaspartics and -30°F (-34°C) for another.^{[1, 2]} So polyaspartic has more cold-weather options, but fast-cure epoxies also go down near freezing. The product decides.^{[2, 6, 24]} Covestro does say polyaspartic cure depends less on temperature than other two-part coatings.^[17]

Heat and humidity work against polyaspartic. It cures faster with moisture in the air, and heat shortens its pot life.^{[4, 28]} Sika sets a 75% humidity maximum during application and cure for one product, and warns not to coat while the slab is warming up, or pinholes may form.^[22]

Concrete on the ground can push water vapor up into a coating, and too much can make it blister, bubble or lift.^{[4, 32]} Pros test it two ways. ASTM F2170 measures relative humidity (RH) inside the slab with probes. ASTM F1869 uses calcium chloride to measure how much vapor leaves the surface, in pounds per 1,000 sq ft per 24 hours.^{[37, 38]}

• Many polyaspartics allow up to 75% RH or 3 lb.^{[1, 3, 25]}
• Some allow more. One Sika polyaspartic allows up to 85% RH.^[20]
• On the epoxy side, one primer sets its limit at 75% RH or 5 lb, while a 16 mil fast-cure epoxy base allows 85% RH or 12 lb.^{[8, 24]}
• Above the limit, makers call for a moisture vapor barrier primer first, often an epoxy.^{[3, 18, 25]}

A test is a snapshot. Simiron warns that on a slab with no vapor barrier under it, seasonal ground moisture can exceed the limit whatever the earlier test said, and ASTM says an F1869 result may not indicate future conditions.^{[3, 38]}

Prep is the same job for both. Pro data sheets call for diamond grinding or shot blasting to a concrete surface profile (CSP) of about 2 to 4. CSP is the International Concrete Repair Institute's scale for how rough the prepared surface is.^{[22, 25, 28]} Cracks and spalled spots are patched and ground or scraped flush before the base coat.^{[10, 28]}

We used only prices installers publish as their own, not market ranges. Before citing a business we checked that it is a real, named business with an address or licence we could look up, that it shows real finished jobs of its own, and that its site shows no signs of lead generation. US prices are in US dollars. Canadian prices are in Canadian dollars.

Only M&M Floors prices both here. Its polyaspartic option runs about $2 more per square foot than its epoxy, in Canadian dollars. On a 440 sq ft two-car garage, a $2 gap adds $880.^{[5, 16]} M&M Floors also puts it as a percentage: its polyaspartic-only systems run 25 to 35% more than epoxy-only.^[5]

Read "polyaspartic" prices closely. Two of these installers' polyaspartic floors are a polyurea base with a polyaspartic top, not polyaspartic in every layer. Compare quotes layer by layer.^{[15, 16]}

Why it costs more: Elite Crete says polyaspartic has a higher material cost than basic epoxies.^[4] Installers add that its short working time calls for a bigger, experienced crew.^{[5, 32]} Croc Coatings adds that a thin polyaspartic build will not level deep pitting the way a thick epoxy mortar coat can, so a rough slab may need extra prep.^[15]

The recoat window is the time in which the next coat bonds without sanding. For most pro epoxies and polyaspartics it is about 24 hours. After that, the surface has to be sanded first.^{[6, 22, 23]} Simiron says other topcoats should go onto its polyaspartic while it is still soft.^[28] Some products allow longer: 7 days for one pro epoxy and for one DIY kit.^{[7, 35]}

Local repairs are possible. Laticrete's repair steps for its polyaspartic floors are: remove loose coating, sand the spot and the coating around it, wipe with solvent, put the system back to its original thickness, and keep traffic off for at least 24 hours.^[39] A repaired patch may not match exactly. One maker's warranty excludes those differences in appearance.^[33] Simiron notes that heavy traffic areas may need reapplication over time.^{[10, 28]}

Coating over an old epoxy floor depends on its condition. GLI Epoxy Flooring in Toronto says a well-bonded, intact epoxy floor can sometimes take a polyaspartic topcoat after prep and scuffing, but peeling, bubbling or delaminated epoxy must come off first.^[14] Integrity Concrete Coatings says it usually removes the old coating so the new system bonds to prepared concrete.^[27] Makers' install guides differ by system. Laticrete's and Simiron's polyaspartic chip floor guides say to remove previous coatings, while Simiron's epoxy-base flake guide says to grind off any topcoat that is not epoxy based.^{[10, 25, 28]}

No manufacturer data sheet we read gives a lifespan in years for either chemistry. The material warranties on the pro data sheets we read run 1 year, and the ones that spell out terms exclude labor. Longer warranties exist, with conditions (see below).^{[1, 3, 6, 22]}

Lifespan figures come from sellers. M&M Floors near Edmonton, which sells both, estimates 15 to 20 years for epoxy and 20 to 25 for polyaspartic in an Edmonton garage. That is one company's estimate, not a test result.^[5]

"Lifetime" warranties have limits. One maker's limited lifetime residential warranty covers UV discoloration of its polyaspartic topcoat and peeling or delamination. It needs an authorized dealer install and registration within 30 days, and it generally ends when the home changes hands. It excludes cracks, marks from soft tires or tire shine, slab moisture, brake fluid and battery acid, and labor.^[33] Ask any installer for the warranty in writing, and read the exclusions.