How to Restore Terrazzo Floors

Years of wear and tear can leave your terrazzo floors looking dull. Restoring them to their former glory is a complex process that requires specialized equipment and expertise. In the video above, This Old House host Kevin O’Connor visits Del Ray Beach, Fla., to witness the impressive transformation of tired terrazzo flooring. The guide below will show you how to restore terrazzo floors in your own home.

Understanding Terrazzo Flooring

Terrazzo is a composite material consisting of marble, quartz, granite, or glass chips set in cement, epoxy, or resin and polished to a smooth surface. The combination of these materials creates a unique, speckled appearance. 

This flooring type has been used for centuries since its origin in Venice, Italy. Terrazzo’s durability and aesthetic appeal have made it a popular choice for both residential and commercial spaces.

But over time, terrazzo floors can stain, lose their shine, crack, or chip. Routine maintenance can mitigate some of these issues, but others may require professional intervention. Full restoration goes beyond simple cleaning and polishing to include a multi-phase grinding process and meticulous patching. 

The Terrazzo Restoration Process

While homeowners can perform minor maintenance, we recommend leaving full restoration to a professional. However, it can be helpful to understand the tools and steps involved.

Tools and Supplies

Terrazzo restoration requires not only expertise but also several pieces of specialized equipment. Here’s what you would need.

Preparation

Before the actual restoration begins, remove all furniture and obstacles from the area. Clean the floor thoroughly to remove surface dirt and debris. Then, cover the lower 24 inches of the room’s walls with plastic sheeting to protect them from water and debris. Note any issues that require special attention, such as high-traffic areas, heavily stained sections, or damaged spots. 

Consult with your contractor to see which parts of this process you can handle yourself and which they will do. Proper preparation can streamline the process and prevent delays.

First Grinding

The first major step in the restoration process is grinding the floor to remove the top layer and expose the aggregate beneath. Here are the basic steps:

1. Prepare the grinder: Install 30-grit diamond disks onto an electric floor-grinding machine. Add steel weights to the machine to increase downward pressure.
2. Wet the floor: Wet the floor with a garden hose. Grinders like the one in the video have a reservoir that allows the operator to release more water as necessary.
3. Grind the floor: Grind the floor in both east-west and north-south directions, slightly overlapping each pass. Go over the entire floor four times in each direction, for a total of eight full passes.
4. Grind the edges: Use an angle grinder to smooth areas the main machine can’t reach, such as edges and corners.

This messy stage removes imperfections and levels the surface, creating a fresh canvas for subsequent steps.

Progressive Refinement

After the initial grinding, the contractor will move through a series of increasingly fine diamond disks to gradually smooth the surface. Each time the disks are changed, a little more weight is removed.

The contractor will continue until reaching the finest grit (typically 3,500), checking the floor regularly for uniformity and adjusting their technique as needed. The higher grits polish the aggregate and the cement matrix to a near-gloss finish.

Patching and Repairs

Once the floor has been fully smoothed, it’s time to address any holes or damaged areas. Patching involves a five-step process:

1. Enlarge the holes: Use an electric chipping hammer to enlarge the holes.
2. Prepare the patch: Mix polyester stone adhesive cream hardeners and marble chips that match the floor’s colors.
3. Patch the floor: Fill the holes with the adhesive mixture and allow the patches to harden.
4. Grind the patches: Smooth out the patches using an angle grinder with progressively finer grits of sandpaper.
5. Blend the patches: Wet the floor with a sponge, then use resin diamonds to blend the patched areas seamlessly with the surrounding floor.

The use of matching marble chips in the adhesive mixture and careful blending makes the repairs almost invisible.

Polishing

The next step in restoring the terrazzo is polishing, which brings out the floor’s natural luster. Here’s how it works:

1. Apply polish. Spread an acid-based compound polish over the floor and mix it with water. 
2. Polish the floor. Make multiple passes over each section with a wet polishing machine, releasing water from the machine as you go to create a slurry.
3. Clean, dry, and buff. Clean and dry the floor thoroughly, then buff the surface to achieve a high-gloss finish.

Polishing not only gives your terrazzo floors a glossy finish but also seals the surface, offering some degree of protection against future wear and tear.

Sealing

Sealing helps protect the surface from stains, moisture, and wear, ensuring the longevity of your freshly restored floors. The first step is selecting the appropriate sealer for your terrazzo floor. There are two main types of sealers: penetrating sealers and topical sealers.

• Penetrating sealers are absorbed into the floor’s pores, providing protection from within without altering the surface’s appearance. As such, they are often the best choice for terrazzo floors in high-traffic areas.
• Topical sealers, on the other hand, form a protective layer on the surface of the floor. They enhance the gloss and shine but may require more frequent maintenance as they can wear down over time.

Applying the Sealer

The floor should be completely clean and dry before sealing to ensure proper adhesion. If the floor has been recently polished, make sure all residue, dust, and debris have been thoroughly removed. Using a clean microfiber mop or a paint roller, apply the sealer in thin, even coats.

Typically, two coats are applied for optimal protection. Allow the first coat to dry completely before applying the second. Make sure to ventilate the area well during the sealing process, especially if using a solvent-based sealer.

Drying and Curing

After the sealer has been applied, it needs time to dry and cure fully. Depending on the type of sealer used, drying times can vary from a few hours to 24 hours. During this time, avoid walking on the floor or placing any furniture back in the room. Ensure the room remains well-ventilated to allow the sealer to dry properly.

Maintaining Restored Terrazzo Floors

Routine care will keep your newly restored floors looking their best and extend the time between major restorations.

Regular Cleaning

Daily and weekly cleaning prevents dirt from becoming embedded in the floor or scratching the surface. Sweep or dust-mop daily to remove abrasive particles. Once a week, clean the floors with a pH-neutral cleaner and microfiber mop. Avoid using harsh chemicals or acidic cleaners that can etch the surface.

Periodic Polishing

Periodic polishing refreshes the surface and maintains the reflective quality of the floor. To maintain a high-gloss finish, apply a specialized terrazzo polish every few months. Use a soft cloth or machine buffer for even distribution. You may also want to invest in professional polishing annually or bi-annually, depending on foot traffic.

Protecting the Surface

A few preventive measures can help protect your floors from common causes of damage, such as scratches and stains. Clean spills immediately to prevent staining. Avoid dragging heavy objects across the floor, and use felt pads under furniture legs. Place mats at entrances to trap dirt and moisture.

Our Conclusion

Restoring a terrazzo floor requires specialized equipment and expertise, but investing in professional restoration is worth it. With proper care and maintenance, professionally restored terrazzo floors can continue to impress for decades to come.