THE BOOK ON GARAGE FLOORS
HOW TO INSTALL GARAGE FLOORS FROM A TO Z
(NOT 1, 2, 3)
BY DONALD EUGENE SANDERSON JR - HOUSTON TEXAS USA
Epoxy vs Urethane
Floor coatings are super heavy duty glues that have color powder (pigment) added to them so that they have a solid color. Glue has a hard time sticking to a smooth surface. This is why it is easier to glue your porous fingers together with super glue than non-porous plastic, glass, or metal. Neither 2 part epoxy or 2 part urethane or 2 part acrylic will stick to a smooth surface. Glue needs a porous slightly textured surface to soak into and grip onto. If we were to coat a garage floor as-is (with no preparation) it would peel, not because the coating failed, but because we failed to give it something to grip onto. Garage floor concrete is typically smooth because it is finished like indoor concrete with a trowel which makes it smooth and relatively non porous at the top surface. Therefore if we want to apply a coating that stays stuck then we have to rough up the top surface of the concrete so that the coating has something to grip onto. When you make scratches, grooves, channels, and large pours in the concrete by diamond grinding you can then embed half of your floor coating below the surface of the concrete and it will be impossible to separate the two without first destroying the concrete.
When a properly installed floor coating peels it will have concrete particles stuck to the bottom of the peeled floor indicating that the bond between the coating and the concrete never broke, on the contrary, the concrete crumbled and shed from itself causing the peel.
Urethane has a much higher tensile strength than epoxy does which means that when pulled apart urethane is much stronger than epoxy. Urethane also sticks much better. Urethane is also UV stable which means it does not yellow like epoxy. Epoxy yellows fast and it only gets worse over time so that the epoxy always looks dirty and dingy.
Nevertheless epoxy is half the price of urethane, so it is more profitable to sell which makes it the first choice of most when on a budget and unaware that it is weaker and does not stick as well.
Epoxy vs Polyaspartic Urethane
Adhesion Strength Test
Epoxy Adhesion Strength - 300 psi
Polyaspartic Urethane Adhesion Strength - 425 psi
Urethane Wins the Adhesion Strength Test!
Urethane sticks 141% Better than Epoxy!
Tensile Strength Test
Epoxy Tensile Strength - 3,527 psi
Polyaspartic Urethane Tensile Strength - 6,400 psi
Urethane wins the Tensile Strength Test!
Urethane is 181% Stronger than Epoxy