How to install a full-broadcast flake floor, step by step

A full-broadcast flake floor goes down in layers over mechanically ground concrete: a thin primer, a pigmented epoxy base coat, vinyl flake thrown into the wet base until no wet spots show, a scrape and vacuum, then a clear topcoat. For a 440 sq ft two-car garage, that’s roughly 63–88 lb of 1/4-inch flake for a full broadcast, and two to three working days with an epoxy base and a polyaspartic topcoat.

The thicknesses, coverage rates and cure times below are for a complete professional system, Simiron’s SimFlake SB. Other systems follow the same order with their own numbers; always work from the system guide for the products you buy. If you’re new to the overall business, start with how to start an epoxy flooring business.

The system in layers

The finished system averages about 60 mils nominal. A mil is a thousandth of an inch; see mil and spread rate in the glossary.

Step 1: Inspect the slab and test for moisture

Walk the floor before you quote: cracks, spalls, old sealers or paint, oil stains, and where the slab meets the garage door. Then test for moisture, days before the install, because the tests take time. Standard epoxy and polyaspartic systems allow a moisture vapor emission rate of up to about 3 lb per 1,000 sq ft per 24 hours by ASTM F1869, or 75–80% relative humidity by ASTM F2170, depending on the product. Above that, the system needs a moisture-vapor-barrier primer rated for wetter slabs; some handle up to 25 lb or 95% RH at 16 mils. New concrete must cure at least 28 days. How to run the tests: concrete moisture testing.

Step 2: Grind to the right profile

Diamond grind or shotblast bare concrete to a profile of CSP 3 or more. On a previously coated floor, grind with 30-grit metal diamonds until any grout or topcoat that isn’t epoxy is completely gone. Compare the floor with CSP chips rather than judging by eye; concrete surface profile explains the scale.

Grind with the grinder connected to a dust extractor. If you have employees, OSHA’s silica standard requires the maker’s recommended dust collection system with a 99%-efficient filter and, indoors, a HEPA-filtered vacuum between passes.

Step 3: Edges, cracks and joints

• Edges. Grind along walls, around posts and into corners with a hand grinder and shroud. The coating needs the same profile at the edge as in the middle.
• Cracks and spalls. Patch cracks, holes and spalled areas with epoxy crack filler, or a 100%-solids epoxy thickened with fumed silica, scraped flush. Check again after priming; the primer shows what still needs patching. Crack and joint repair before coating covers which cracks to fill and which to honor.
• Joints. Honor isolation, expansion and moving joints with joint material after the coating is installed. Contraction (sawcut) joints can be filled and coated over, but the coating may crack there if the slab moves. Tell the customer before you start.
• Termination points. Sawcut and key in the coating where it ends at drains and high-traffic impact points. Where the coating stops at the garage door is a termination point too. Where walls meet the floor, a cove base carries the system up the wall.

Step 4: Clean, tape and set up

HEPA-vacuum the whole floor; don’t dry-sweep concrete dust. Tape the perimeter where the coating will stop. Set up a mixing station as close to the floor as you can, covered with plastic or cardboard taped down, with every tool, kit and piece of PPE laid out before the first mix.

Step 5: Prime

Mix only what you can apply in 10–15 minutes: pre-mix the base for one minute, add the activator, and mix for three minutes. Pour a long bead and spread it with a flat squeegee or spring blade at 3–8 mils. A tight, thin coat of primer with no back-roll is the best way to keep outgassing bubbles out of the floor.

Timing matters too. Apply the first coat when the slab is at its warmest and starting to cool, so the resin is drawn into the pores instead of air being pushed out through it. In a garage that warms up during the day, that usually means later in the afternoon rather than first thing in the morning. A 100%-solids epoxy primer is typically ready for the base coat after about 6 hours and has to be recoated within 24.

Step 6: Base coat and broadcast

1. Tint the base to the flake. Tint the clear base to match the main color of the flake blend, so any spot the flake misses doesn’t stand out.
2. Mix and pour. Same routine: one-minute pre-mix, three-minute mix, no more than you can apply in 10–15 minutes, poured straight onto the floor in an 8–12-inch bead. Don’t scrape the pail or turn it over to drain; unmixed material running down the bucket walls leaves sticky spots.
3. Spread. Wearing spiked shoes, pull a 1/8-inch notched squeegee along the bead at 8–12 mils, then back-roll with a 3/8-inch shed-resistant roller to even out the film.
4. Broadcast. Give the base 10–15 minutes to level, then throw the flake. Grab loosely, throw it high into the air, keep moving around the area instead of standing in one spot, and don’t crush the flakes in your hand. Leave a wet strip at the edge of each section so the next mix can tie in.
5. Go to rejection. For a full broadcast, keep throwing until the base won’t accept any more and no wet spots show. A single, lighter broadcast rarely covers the epoxy completely, which is why the base is tinted to match.

How much flake. At full broadcast, 1/4- and 1/8-inch flake covers about 5–7 sq ft per pound, 1/16-inch and hybrid blends about 3–5. Partial broadcasts cover about 25–50 sq ft per pound for heavy coverage, and more for a light scatter. For 440 sq ft of 1/4-inch flake: 440 ÷ 7 = 63 lb to 440 ÷ 5 = 88 lb. The flake calculator does this for any floor and blend.

Step 7: Scrape and vacuum

Once the base has cured enough to walk on (a standard-cure 100%-solids base takes light foot traffic after about 10 hours and can be recoated after about 8 hours at 72°F), vacuum the loose flake. Then scrape the whole floor with a long-handled floor scraper to knock off loosely bonded chips and sharp edges without damaging the coating, and vacuum again.

Step 8: Topcoat

The clear coat locks the flake in and takes the wear. A slow-cure polyaspartic topcoat goes on at 100–160 sq ft per gallon for a 10–16-mil wet film, spread with a flat or notched squeegee and back-rolled with a 3/8-inch roller. The rules that matter:

• Mind the window. The epoxy base has to get its topcoat within 24 hours; miss it and the floor has to be sanded first.
• Watch humidity. Polyaspartic cures faster in humid air: a slow-cure version gives about 70 minutes of working time at 72°F and 20% humidity but only about 28 minutes at 80%. In hot or humid weather, dip-and-roll from a pan with an 18-inch roller.
• Keep tie-ins fresh. Don’t let more than 5–10 minutes pass between mixes, and use joints as natural breaks.
• Don’t flood it. Applying it thicker than specified, letting it pool, or rolling into material that has started to set can leave a white, hazy finish.
• Second coat for a smoother feel. A 6–8-mil second coat can go on within 24 hours if the customer wants less texture.

Slip resistance

Flake under a clear coat leaves texture. A slow polyaspartic topcoat at 14 mils over full flake tests at a wet dynamic coefficient of friction of about 0.63 under ANSI A326.3, well above the 0.42 the standard sets for level interior floors that get walked on wet. A second, thicker topcoat makes the floor smoother; for ramps or wet areas, add an anti-slip aggregate.

Cove (optional)

In kitchens, labs and other wash-down spaces, the coating often runs up the wall as an integral cove base, usually with a ¾-inch or 1-inch radius. In a residential garage it’s an option to price separately, not part of the standard system.

Step 9: Cure and return to service

Typical times for this system:

Cold slows every number in this table. Epoxy cure time, temperature and humidity explains how to plan around the weather and the dew point.

A typical sequence for a two-car garage

For a 20 × 22 ft (440 sq ft) garage at about 72°F:

One-day systems compress this. A one-day polyaspartic flake system skips the primer, uses a fast-cure polyaspartic as the base, broadcasts flake immediately before the surface skins over, and finishes with a slow-cure polyaspartic topcoat. The trade-offs are covered in polyaspartic vs epoxy.

Mistakes that cost callbacks

• Skipping the moisture test. Moisture vapor coming up through the slab peels coatings off.
• Under-grinding. A smooth, sealed or troweled surface gives the primer nothing to grip.
• Skipping the primer on porous concrete, then chasing outgassing bubbles in the base.
• Mixing fast or partially. High drill speeds whip in air; partial kits throw off the ratio.
• Uneven broadcast. Crushing flakes in the hand, rushing, and using the settled fines from the bottom of the box all leave blotchy areas.
• Late topcoat. Past the 24-hour window, the base must be sanded before it will bond.
• Thick, pooled topcoat that dries hazy.
• Uncovered base coat. An epoxy base left showing between chips yellows over time in sunlight; full coverage and a UV-stable topcoat protect it.

More failure modes, with causes and prevention, are in why epoxy floors fail.