What flooring can go directly over concrete?

When it comes to installing new flooring in your home, one of the most common substrates is a concrete slab. Concrete provides a durable, stable base for flooring, but not all types of floors can be installed directly over concrete. The key considerations are the flooring material, the condition of the concrete, and proper preparation. In this article, we’ll discuss the flooring options that can go directly over concrete and the steps needed to ensure a successful installation.

Tile

Tile is one of the most popular choices for concrete subfloors. The rigid nature of tile allows it to be installed directly over concrete without an additional subfloor. Tiles made of ceramic, porcelain, or natural stone are commonly used. When properly prepared, the concrete creates an ideal foundation for the tile. This prevents cracks, chips, and other damage over time.

There are a few factors to keep in mind when tiling over concrete:

• The concrete must be fully cured and dry. New concrete requires up to 90 days to adequately cure and dry.
• The surface should be free of contaminants like paint, wax, oil, etc. These can prevent proper adhesion.
• Concrete should be flat within 1/8 inch over 10 feet. Greater variations may require leveling compounds.
• Textured or porous tiles often require a tile-bonding mortar to create adhesion.

With proper subfloor prep, tile can adhere directly to concrete for a beautiful, durable finished floor.

Tile Installation Tips

Here are some tips for a successful tile installation over concrete:

• Use a concrete primer before setting tile to improve adhesion.
• Check floor flatness and use leveling compounds if variation exceeds 1/8 inch.
• Follow all manufacturer instructions for mortars, adhesives, and grout.
• Use backer boards for lightweight tiles or those with high moisture sensitivity.
• Use a high quality polymer-modified thinset mortar suitable for concrete.

Vinyl Flooring

Vinyl is another excellent choice for concrete subfloors. Materials like luxury vinyl plank (LVP), luxury vinyl tile (LVT), and sheet vinyl can be installed directly over concrete in most cases. Vinyl is more forgiving and able to flex over minor variations in the substrate. It also provides cushioning and comfort underfoot.

As with tile, there are some important considerations when installing vinyl flooring over concrete:

• Moisture testing is critical to check for high vapor emissions that can cause flooring failure.
• Concrete must be clean, dry, and free of contaminants like adhesives, sealers, curing compounds, etc.
• New concrete should be cured for at least 60 days prior to installation.
• Use a suitable primer and adhesive formulated for concrete substrates.
• Follow the manufacturer’s recommendations for subfloor prep and installation.

Vinyl Installation Tips

Here are some helpful installation tips for vinyl flooring over concrete:

• Conduct moisture testing with a calcium chloride test per ASTM F1869.
• pH testing should also be performed to check for alkalinity.
• Smooth uneven surfaces with a suitable patching compound.
• Use an embossing leveler for highly textured concrete.
• Allow proper open time for adhesives to develop tack before setting flooring.

Laminate Flooring

Laminate flooring can also be placed directly over concrete in certain circumstances. Most laminate floors have an attached underlayment pad to provide resilience and moisture protection. While laminate is not impervious to moisture, modern laminate floors use water-resistance treatments and materials to withstand minor moisture exposure.

Tips for installing laminate flooring over concrete:

• Test concrete moisture levels, which should not exceed 3 lbs per 1,000 sq ft over 24 hours.
• Use a suitable moisture barrier like 6 mil polyethylene sheeting.
• Install boards perpendicular to joints in the concrete to prevent telegraphing.
• Include expansion gaps around perimeter and fixed objects.
• Use rubber underlayment for additional moisture and sound protection.

With proper preparation and product selection, laminate can be suitable for concrete substrates in many residential applications.

Engineered Hardwood

Engineered hardwood floors can also be installed over concrete in some cases. Engineered hardwood has multiple layers of plywood or high-density fiberboard with a top veneer of solid wood. This construction makes engineered floors more dimensionally stable and less prone to moisture damage compared to solid wood.

Tips for installing engineered hardwood over concrete:

• Moisture barrier is required between concrete and engineered flooring.
• Use engineered hardwood rated for concrete installation, typically 3/4 inch thick.
• Install perpendicular to direction of concrete seams.
• Follow all manufacturer instructions for subfloor prep and installation.
• Maintain proper room relative humidity between 30-50%.

With extra care taken for moisture protection, engineered hardwood can be a good option over concrete. But moisture issues can still arise over time, so solid hardwood is generally not recommended.

Concrete Subfloor Preparation

Proper subfloor preparation is critical when installing flooring over concrete. The key steps involve:

1. Cleaning: Concrete must be free of dirt, waxes, oils, paints, curing compounds, adhesives, and any other contaminants.
2. Patching: Fill any cracks, holes, and other defects with a cement-based patching compound.
3. Moisture Testing: Check moisture vapor emissions and alkalinity.
4. Priming: Use primer to improve adhesion and create a bonding layer.
5. Leveling: Smooth any variations in flatness with a suitable leveling compound.

Taking time to correctly prep the concrete prior to flooring installation helps ensure a long-lasting, trouble-free floor.

Flooring Type	Can Be Installed Over Concrete?
Ceramic, Porcelain Tile	Yes
Natural Stone Tile	Yes
Vinyl Tile	Yes
Luxury Vinyl Plank	Yes
Sheet Vinyl	Yes
Laminate	Sometimes*
Engineered Hardwood	Sometimes*
Solid Hardwood	No

*With proper moisture testing and protection.

Conclusion

Installing flooring over a concrete slab can expand your design options well beyond carpet. With proper preparation and product selection, options like tile, vinyl, laminate, and engineered hardwood can be suitable for concrete subfloors. Always follow manufacturer instructions carefully, perform moisture testing, and take time to correctly prep the concrete surface. This will help ensure many years of enjoyment from your new floor over concrete.