How to Lay Terrazzo Floors

close up view of terrazzo flooring
  • 48-96 hours
  • Advanced
  • 600-800
What You'll Need
Marble chips or other stone aggregates with sizes and colors based on the design needed
Portland quick-dry cement
Metal divider strips, preferably zinc or brass
Some leftover plywood strips
Hydrochloric/muriatic acid
Stone floor grinder, from coarse to fine grade of grinding stones
Circular saw fitted with a masonry blade
Pressure washer
Wheelbarrow or cement mixer, depending on the quantity of terrazzo and cement to be used
Heavy-duty floor roller
Concrete finishing trowel

If you're looking to add some "pizazz" to that bland flooring, then using terrazzo floors is the surest way to go to get that colorful and intricate design while offering durability and being inexpensive at the same time. Basically, terrazzo is a type of flooring that consists primarily of a mixture of concrete and marble chips or other aggregates of stone. This mixture is placed on an already-present concrete slab, then polished to a shiny, smooth finish. The process of laying it down is a bit complex, so you need an assortment of materials and tools before you consider pursuing this kind of project. But if you're keen and confident enough with your do-it-yourself abilities, this should be a walk in the park for you.

Step 1 - Prepare the Concrete Slab

Prepare the concrete slab by putting some grooves into its base using the circular saw equipped with a masonry blade. Each groove should have a depth of 1 inch and a thickness of 0.375 or 3/8 of an inch, and should be spaced out at least three feet diagonally from each other. The purpose of these grooves, which are also called control joints, is to protect the eventual surface of the floor from any fissures that may occur with the terrazzo.

Step 2 - Attach the Metal Dividers

Sweep the floor, then drench it with clean water using the pressure washer. Using a mixture of hydrochloric acid and water, add 3 tablespoons to 1 gallon of water proportion, thoroughly scrub the floor then wash it down again with water using the pressure washer. Now, carefully attach the metal divider strips to the network of controls joints you made then affix those leftover plywood strips around the edges of the floor to prevent the terrazzo from pouring out of the intended section.

WARNING: Hydrochloric acid is toxic when inhaled, so wear a respirator mask and safety glasses during this step.

Step 3 - Mix Terrazzo

mixing concrete in a wheelbarrow

To make the proper terrazzo mixture using the Portland quick-dry cement and marble chips, the right quantity necessary is 94 pounds of cement, which is typically one bag, per 200 to 220 pounds of marble chips. Mix them using the wheelbarrow or cement mixer, depending of the quantity of the mixture, adding the precise amount of water as specified by the cement company instructions.

Step 4 - Apply Terrazzo

With one wheelbarrow amount of mixture, apply it accordingly to the floor and spread it at once by means of your floor roller. To make sure the marble chips are evenly and firmly bonded to the floor, press them correspondingly with the trowel. Apply further amounts of marble chips liberally onto the floors so that there are a bunch of marble chips loosely scattered. Then use the floor roller again to pack the terrazzo mix together and to expel the air bubbles that may have formed during the application process.

Step 5 - Polish

using a floor polisher

After letting the terrazzo mixture cure for approximately 2 days, use the stone floor grinder to polish off your terrazzo floor. Start off by using the coarsest grade of grinding stones first then gradually work your way up to the fine grade stones, making sure that you pass each and every section of the floor. The floor is polished enough when the divider strips and marble give off a noticeable shine. Then use the pressure washer again to wash away all the dust made by the polishing.

Step 6 - Remedy Air Bubbles

Sometimes, there could still be some air bubbles left over, causing very small pinpricks to appear on the surface of the floor. You can remedy this by applying a generous amount of cement mixture or slurry, made up of your quick-dry cement and water, onto the whole floor. Make sure that it is spread very thinly to cover those tiny holes, then meticulously scrape off the excess layers with your trowel.

Step 7 - Finish Up

Do another round of polishing with your floor grinder using the finest grade to finish it off and to give that flawless sheen to your brand-new terrazzo flooring.