How To Level A Floor

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Most homeowners are not aware that their floors can be out of level, and it has a major impact on the aesthetic appeal of your home. It is important to know how to level a floor whether you’re building a new house or remodeling so you can keep your house safe and looking great for years to come. 

There are also a number of reasons why your floor can fall out of level with the rest of your home. Such reasons include non-leveled subflooring, shifting foundation, or a poorly engineered floor joist system. Knowing the required techniques will help you understand the problem before getting the floor checked and repaired by a professional.

Whether you're installing ceramic tile, hardwood, or laminate, make sure your subfloor foundation is level. Here are the steps to help diagnose unevenly floor:

Remove the Existing Flooring

If you are installing a new floor in your old house, you need to remove the old floor. This step is important because it determines whether your subfloor will be level or not. Pull up one section at a time of that squeaky hardwood floor by using a pry bar. If there's a gap between the floor and the wall, you have to fill up that gap with wood filler. Once your old floors are removed, get rid of any debris or nails remaining on the subfloor by brushing them away.

Check the Level and Structure of Your Floor

Check why your floor is unlevel. You can do this by stripping out a thin layer of wood around the perimeter of the room. This way, all floor materials, including the subfloor, will be level. There are many reasons why your floor is not level, and each of these reasons requires a specific approach in terms of repairs.

Not every floor situation will require these steps. But the first step you must never forget with your flooring level is to use a level, straight edge, and a hammer to knock down any and all high spots. The level will also help you determine which direction your floor needs to slope in order to form a level plane.

Inspect and Diagnose Your Floor

Make sure you get to the root cause of your flooring problem. Is it a high spot that needs to be leveled, or is it a low spot that needs to be sloped? Sometimes the problem isn't with your floor level at all,  it's actually in your subfloor. The subfloor may not have been installed correctly. Or there could be decay, dry rot, or mold damage beneath the floor. Leveling the floor without correcting the underlying can result in a fix that only turns out to be temporary.

Therefore, it's a good idea to call in a contractor to look for trouble spots such as rotten wood, cracking, or moldy plywood. You don't want to tear up a perfectly good floor only to find that moisture has damaged the subfloor. The contractor should be able to test the subfloor for areas of weakness. They should also inspect the floor, drywall, and subfloor layers to find out if the floor slants, such as in a house with a hill.

Replace the Framing

Once you've thoroughly inspected the floor and have all the problems diagnosed, now you should start repairing. If there's moisture damage or insect infestation, you'll need to replace the affected boards. Make sure that all bad wood is removed and replaced; otherwise, you'll get problems later on down the road.

Make sure you replace the rotten girders, band joists, and floor joists if they're rotted or deteriorated. If you can't replace this affected insulation yourself, you may need to hire a professional to do the job. Once you've installed new joists and girders, now it's time to get rid of floor squeaks. There are several different ways to solve this common problem, depending on what flooring material is currently being used.

Raise the Floor and Fix the Sags

If you have an uneven floor that is sagging in some areas, the best way to fix this problem is by raising the entire floor. First, use a Sawzall to cut away any nails or screws holding down the existing subflooring and remove it. Next, you'll need to apply construction adhesive onto several beams across all joists.

Toenail these beams into place and use a leveler to make sure they are completely even before the adhesive dries. It is important that you use wood beams instead of steel ones in order to avoid any additional weight on the flooring material. Once all joists are leveled, apply construction adhesive onto them as well as across your new laminate floorboards. Lay the flooring and nail it into place.

Once all boards have been laid, let construction adhesive dry overnight before you caulk around them with a waterproof caulking compound to create an airtight seal. Leave this for at least 24 hours, and then reapply the compound to be doubly sure that your walls are protected.

Plan Your Layout

Plan the layout of your plywood sheets to enable you to utilize the least number of boards in your pack. Using a tape measure, mark out the length and width of each room onto the back of each board so that you can work more efficiently. Make sure that you leave a 1/4″ gap all around between each sheet.

Ensure the plywood's short sides are centered over joists, and the long sides are flush against the walls and ceiling. The bottom edge should be fitted so that it's flush with your subfloor. Make sure there is self-leveling underlayment from the joints of your plywood sheets and secure sheets to the floor joists with 2 1/2″ or 3″ nails. Nail from the center of each stud outwards.

Sand Down High Spots

While sagging and slanted flooring materials are the main cause of unlevel floors, humps can also cause tripping hazards. If you place a level on top of the hump, it will read the level or be higher than the lines marked alongside. A simple solution to this problem is to sand down high spots with an electric sander. It can take a while, but in the end, you'll have a smooth floor that's easy to level. 

You can also use a motorized angle grinder to remove high spots, but this is a more dangerous option. Be careful when using power tools to sand down your flooring for leveling purposes, as they can cause gouges or other hazards. Wear eye protection and a face mask or ventilator to prevent inhalation of dust or fumes.

You can also fill in low spots with epoxy adhesive mixed with sand to give it more body. If the floor has a large amount of slant, you may install level boards underneath to even out the floor. Make sure that these boards are secure and won't shift under your weight when you walk on them.

Clean and Repair Old Subflooring

Before laying your new flooring, clean up the subfloor and scrape off any old adhesive. Smoothing with a putty knife is usually enough to remove most of the residue. Unfortunately, this process can be time-consuming for large areas. A faster way is to use an adhesive remover meant specifically for removing adhesives from concrete.

Make sure you vacuum the entire room, especially around the corners of the room. There you'll have to dig out dirt and grime that may be trapped in corners or under the floor where it can't escape. When mopping concrete subfloors, use muriatic acid to clear any traces of oil or grease, then a disinfectant to kill any microbes. 

Fill cracks in the concrete subfloor and ensure the filled areas are dry before starting the floor leveling process. Do thorough cleaning to get your subflooring ready for floor leveling.

Check for Minor Irregularities

Lay a long straightedge along the floor, and check for any minor cracks or slight depressions. It's important to get these out of the way before applying floor leveling compounds. They'll only inhibit the final result. Use a chisel and hammer to chip away at them, then clean with a damp cloth.

As you move your straightedge across the floor, you'll notice some low spots where it doesn't sit flush. Use a block of wood and your hammer to tap down into those spots until you get the right height.

Cover Your Subfloor with Bonding Agent

Start with the edges of your room, along with molding and baseboards. Scrape a little bit of thin-set adhesive out onto your straightedge, and spread it about two inches along with the flooring you'll be bonding it to. Press down firmly in order to form a seal between both surfaces. If you find any seams or gaps, cover them too with this thin layer of bonding agent.

Cover Your Subfloor with Bonding Agent
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Mix the Leveling Compound to a Creamy Consistency

Follow the manufacturer's directions with regards to how to mix your leveler. You want the mixture to have a paste-like consistency that will easily flow out onto your subfloor when you start applying it using a notched trowel. Spread it evenly at a rate of four or five square feet per gallon of dry material, and use the 8-inch side of the trowel for the initial spreading.

Your mixture should have the same texture as pancake batter. It should flow out easily but not be too runny. After that, stir the mixture vigorously to break up lumps and get rid of air bubbles and voids.

Add Subfloor Sleepers

Once your floor frame and walls are aligned and laid out, it's time to add the sleepers that will serve as a subfloor. The terms subfloor and sleepers are interchangeable. Any flat boards or dimensional lumber that is suitable for use as flooring can be used as sleepers. 

Add Subfloor Sleepers
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This will give your new leveled subfloor a new height. The gap that will be created between the sleepers and the current floor height can be filled with a filler material made up of sawdust, pea gravel, and a floor leveling compound. The manufacturer recommends 3 lbs. per square foot. The subfloor sleepers will help to prevent cracking of the leveling compound.

The floor leveling system is then installed over the sleepers and the filler material per the manufacturer's instructions. The flooring material can now be laid over the leveler, ensuring that it will have a perfectly smooth surface. Follow your local building code to determine if you need a finished floor or whether an unfinished subfloor will suffice.

Install the New Subfloor

At this point, you may apply a bead of flooring adhesive to the subfloor, but this is optional. It won't hurt to apply it, though, making it easier to install the flooring material later. Then lay the new subfloor on top of the sleepers. Once your new subfloor is locked into place, you will want to use either a nailer or dato blades to cut around any obstacles in the way of the new subfloor.

Install the New Subfloor
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Install Your New Floor

Now that your subfloor is level and locked in place, you can install your new flooring material. You can put hardwood or laminate flooring, tile or carpet, or any other material you prefer. You won’t have to worry about having a flat subfloor to support it.

FAQs on How Level a House Floor

How do I level my floor?

It's a lot easier to remove the old subflooring than to adjust the existing subfloor, so go with that if you have an option. If not, you'll need a sledgehammer and pry bar to remove the nails from your old flooring.

How do you level the uneven floor?

If uneven floor is due to floor joists that have warped or were not installed correctly, then the only way to level it is to remove the subflooring and shim the joists.

Conclusion

Once you have leveled your floor, you will be ready to install your new flooring material like hardwood, tile, or carpet. No bumps or dips will affect the new flooring material as long as the sleepers are in place and secure.  

 

Dino Paccino

Dino Paccino

Dino is a lifelong writer and home improvement specialist. He enjoys bringing cutting-edge information on home renovation and remodeling to Kitchen Infinity.

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