Cement Your Style With a Polished Concrete Floor
Polishing a Concrete Floor at a Glance
- Tools & Materials: Walk-behind diamond disc grinder and discs, concrete sealer, spray pump, microfiber mop
- Step 1: Clean area and fill cracks
- Step 2: Polish with coarse-grit disc
- Step 3: Polish with progressively finer discs
- Step 4: Apply concrete sealer
While most commonly seen in commercial settings like hospitals and restaurants, polished concrete offers several advantages for the modern home. For starters, polished concrete adds a unique aesthetic appeal to a variety of living spaces. It’s easy to clean and resistant to mold, mildew and mites. It can also be an affordable alternative to stone, tile, carpeting or hardwood.
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Our guide details how to polish an existing concrete floor. If you’re interested in polishing the concrete flooring in your home, read on to discover how it’s done.
What’s Polished Concrete?
As the name implies, polished concrete has a shiny, polished appearance after undergoing a specialized treatment process. This specialized process involves multiple passes with a walk-behind diamond disc grinder using progressively finer grits of diamond grinding discs, from 40- to 1,000- or 3,500-grit.
Despite the absence of published standards that specify exactly what constitutes polished concrete, it’s generally accepted among industry professionals that the concrete must undergo a multi-step grinding process that culminates in a 1,800- to 3,500-grit in order to be considered “polished.” However, some polished concrete contractors may only use grinding discs as fine as 1,000-grit (or less), depending on the concrete being polished. A chemical solution called a concrete densifier is also applied at some point during the operation to strengthen the concrete and produce a more attractive polished finish.
Can You Polish an Existing Concrete Floor?
Polished concrete is installed using one of three: polishing an existing concrete floor, installing a polishable concrete overlay on top of an existing concrete floor or pouring a concrete slab specifically tailored for polishing during the initial stages of the home’s construction.
Polishing existing floors is among the most common and affordable methods, as most concrete floors can be resurfaced and polished. Depending on the quality and condition of the concrete, some preparatory work like filling cracks and holes might be necessary prior to polishing.
If the condition of your existing concrete is particularly poor, a popular option is to install a polishable concrete overlay over the existing concrete. This involves applying an epoxy layer onto the concrete, then installing a relatively thin layer of self-leveling concrete over the epoxy. This smooth and level concrete overlay is then polished like a typical concrete floor.
Pouring a concrete slab designed for polished concrete produces the highest quality result, but this is, by far, the most expensive and labor-intensive option. When this is the case, a contractor will usually be employed to oversee the entire process. This includes the design stage, pouring the slab and polishing the concrete.
Can You Polish Concrete Yourself?
While it’s possible to polish concrete yourself, it’s generally not recommended unless you have prior concrete polishing experience. This is especially true if you will be installing a concrete overlay or pouring a brand new pad. As you’ve seen, polishing concrete is a fairly involved process requiring equipment that has a somewhat steep learning curve to use.
Doing it yourself might also not save you as much money as you think, considering the diamond disc polisher can cost as much as $1,000 a week to rent, and the polishing discs may have to be rented or purchased separately. At the end of the day, hiring a polishing concrete contractor might be the most affordable option. However, if you take pride in performing your own home improvement renovations, polishing your own existing concrete floor might still be worth it. However, pouring concrete overlays or new concrete pads should usually be left to the pros.
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How to Polish a Concrete Floor
The process of polishing an existing concrete floor is quite similar to refinishing hardwood floors. Use the following tools and steps to give your concrete floors a beautifully polished sheen.
- Walk-behind diamond disc grinder
- Polishing discs of varying grits
- Concrete sealer
- Spray pump
- Microfiber mop
You can use the following steps to polish an existing concrete floor yourself if you’re sufficiently experienced and equipped.
Step 1: Prepare the Area
The amount of prep work required will depend on the condition of the floor and the method you’ll be using to polish it. Polishing an existing concrete floor or installing a concrete overlay will generally involve the same preparation procedure, including:
- Removing dirt and dust by sweeping and mopping
- Removing existing concrete sealers by grinding, scraping or apply a chemical seal remover
- Filling any cracks, holes or blemishes in the existing concrete
Step 2: Polish With a Coarse-Grit Grinding Disc
Once the floor has been prepared, it’s time to wheel out the grinder. Start with a coarse-grit (40- or 50-grit) grinding disc depending on the hardiness of the concrete you’re grinding. Move the concrete grinder in a circular motion, starting on one side of the room and slowly moving to the other. Slightly overlap the passes you make with the grinder to avoid any bare spots. Some concrete polishers recommend pouring water in front of the grinder to cool the grinding discs and prevent dulling (or “glazing”) the diamond bits.
Step 3: Polish With Progressively Finer Discs
After the initial pass with the coarse-grit disc, you should make anywhere between three and six (or more) passes with progressively finer discs. The total number of passes will depend on the hardness and condition of the concrete, the desired quality of the finished polish and the discretion of the polisher.
As a general rule, the next level of grit you should use in subsequent passes should be at least double that of the previous. In other words, if you used a 40-grit disc on the first pass, you should use an 80- or 100-grit one on the next pass, then a 160- or 200-grit on the following, and so on.
A concrete densifier should be applied at some point during this stage. Again, the optimal timing depends on the condition of the concrete and the discretion of the polisher. Some professionals suggest applying the densifier after grinding with the 80-grit, while others recommend doing so after the 200- or 400-grit. As a general rule, the densifier should be applied to soft- and medium-hardness concrete after polishing with an 80-grit disc; and medium-hard and hard concrete after the 200- or 400-grit disc.
Step 4: Apply Concrete Sealer
After the concrete has been polished to your satisfaction, you should vacuum, sweep and mop residual concrete dust and debris in preparation for a top-coat of concrete sealer. Applying a concrete sealer will protect the concrete from oil, water and other stains while maximizing the longevity of the polished finish.
Pour the appropriate amount of sealer needed for the size of your space into the spray pump, and add the quantity of water that’s indicated by the manufacturer. Spray the sealer onto the concrete and spread evenly with a microfiber mop. Spray and mop one section at a time instead of spraying the entire floor at once. Otherwise, the sealer may cure unevenly.