To make sure your subfloor is level, map the room's high and low spots using a laser level or a straight-edge. Address high spots first by sanding or planing the wood, then fix low spots using a cement-based patching compound or self-leveling underlayment.
Yes, uneven floors can definitely cause dizziness. This happens because the sensory systems your brain uses to maintain balance get confused.
Check the Level of the Subfloor
To check for small high or low spots that may not even be visible, place a long level or straight pipe on the subfloor. Move it around to different areas and mark any high or low spots you find with a pencil or marker. Most floors will have at least some slight variations.
If your subfloor isn't level, it can cause cracking in tile, gaps in wood planks, or a bouncy, squeaky floor. Before installing new flooring, you need to either flatten the high spots or fill in the low spots to ensure your new floor has a solid, even foundation.
To level a subfloor without removing it, first locate and sand down any high spots. Fill low spots with a patching compound, or apply a pourable self-leveling underlayment (SLU) to the entire room. If the floor is severely sloped, install shims and a new over-layer of plywood.
A subfloor needs to be clean, dry, level and structurally sound. Use a level to determine if the floor is level within 3/16-inch change per 10 feet. Mark any high or low spots with a pencil or marker. If you're gluing the new floor to the subfloor, use a sander to remove oil, wax, paint, adhesives or other materials.
The most cost-effective alternatives to self-leveling compound are portland cement and sand mixtures (for deep fills) or thin-set mortar mixed with plywood shims (for localized dips). For large areas, combining a bulk base mix with a thin top layer of premium leveler cuts costs dramatically.
Uneven floors are common in older homes. Before installation, a RiteRug Flooring Expert can inspect your subfloor for dips, slopes, or other issues. Minor imperfections can often be fixed with underlayment or patching, but major gaps may require leveling.
What is the cheapest way to level an uneven floor?
Yes, you can use self-leveling underlayment on plywood, but it requires specific preparation. Plywood flexes and absorbs moisture, so you must secure the subfloor, fill gaps, and apply a manufacturer-approved primer to prevent the leveling compound from cracking, breaking, or delaminating.
Signs Your Subfloor May Be Uneven
Homeowners may notice a slope or dip when walking across the room. This can indicate uneven floors beneath the surface.
For most flooring installations, the subfloor cannot vary by more than 3163 over 16 end-fraction316 of an inch over a 10-foot span, or 18one-eighth18 of an inch over a 6-foot span. For overall structural sloping, the National Association of Home Builders allows a maximum of 12one-half12 of an inch of slope in a 20-foot distance.
Mistakes to Avoid When Applying Self-Levelling Compound
When Should You Worry About Uneven Floors In An Old House? While some unevenness is normal in older homes, certain signs should prompt you to seek professional help. These include: Cracks in Walls or Ceilings: Cracks indicate that your home's structure is under stress and may need reinforcement.
Let's say you have a three foot wide safe that weighs 1,000 pounds, and your floor joists span 12 feet (which is typical). This three foot by 12 foot section of the floor was designed to safely carry a live load of 3 x 12 x 40 PSF, which equals 1,440 pounds.
The "Rule of 3" in flooring is a design principle that recommends using no more than three distinct flooring materials or color variations throughout your entire home. Limiting your design to three elements creates visual cohesion, prevents a chopped-up layout, and ensures smooth, intentional transitions from room to room.
Mix the self-levelling compound: Follow the manufacturer's instructions to mix the compound to the correct consistency. Pour and spread: Pour the compound into the low areas and use a long-handled trowel to spread it evenly across the floor.
Yes, you can absolutely use a self-leveling underlayment (SLU) on a subfloor. However, because wood subfloors are porous and prone to flexing, you must use a product specifically rated for wood and follow strict preparation steps to prevent cracking and leaks.
When Not to Use Self-Leveling Concrete - Top Scenarios to Avoid
To level an uneven subfloor, first identify high spots and low spots using a straightedge and level. Sand down high spots on wood subfloors or use an angle grinder for concrete. Fill low spots using a leveling compound, or raise depressions with shims and underlayment.
A subfloor typically lasts 20 to 30 years, but under ideal, dry conditions, it can last the entire lifespan of the house. Lifespan heavily depends on the material:
Uneven floors in old houses are a normal issue, especially in homes built decades ago. Some minor sloping may be typical. But in many cases, it's a sign of deeper problems, like foundation settlement or crawl space damage, that need attention.
The most cost-effective way to level a floor depends on its current condition. For small bumps, grinding them down with a concrete grinder is cheapest. For uneven areas and dips, using a self-leveling underlayment (around $30 to $40 a bag) or a floor patching compound for minor low spots is best.
Coca-Cola does three main things to concrete: it slows down the curing process (acts as a retarder), etches the surface to expose decorative aggregate, and removes tough stains. This happens because of the soda's high sugar content and phosphoric acid.
You can use several methods to level a floor without traditional self-leveling compounds, including plywood underlayment, floor patch, shims, or even a mud bed, depending on the severity of the unevenness and the type of flooring you plan to install.