Are You Looking For Answers On How To Level A Floor? Read On!

We all know that concrete is famous for its durability, right? You can use it for so many things, from building outdoor fireplaces and garden walls to pouring driveways and laying the foundation for a home. While this is true, it can still be prone to damage. Areas like the garage, basement, laundry room, and landscaping around your home can be vulnerable to imperfections. Sloping, cracking and sinking may still occur since they are usually high traffic areas. Don’t worry, though; what you need is an excellent guide to knowing how to level a floor! 

Cracked concrete in the basement floor texture.

Do you have a noticeable gradient in your home? A wonky, uneven basement floor, or maybe your garage floor? Are you wondering how to level a concrete floor that’s sloped? No matter what the case is, you don’t need to tolerate it any longer! Keep on reading to find all the DIY steps to repair the problem, especially for old houses!

Why you should level a floor

The word “flat” in the tile world means that the surface does not have any significant high or low spots. Wondering how you can determine if the floor is flat enough? Here comes the straight edge tool to help you out. This tool is usually fabricated of magnesium or aluminium and can be an “L” shape or a rectangular box. Find below why uneven floors happen and why you need to level them!

Why uneven concrete floors happen

One of the most common reasons is moisture. If the floor has moisture issues, some parts may swell up and leave the other ones sloppy. Another reason could be that the floors are prone to cracking. Cracks, dips, chipping, and holes may make your floor look uneven. These problems are more common in old houses. Here is where floor levelling comes in!

Why you may need to level your floor

Sloping floors often worry homeowners who want to install new rigid floorings, such as ceramic tile, laminate flooring, or hardwood. When the floor slopes from one end to the other or has sags and dips, it can be a frustrating, vexing problem. Also, the underfloor will determine the finish looks. If there is a new floor in your home improvement plans, it’s essential first to determine if your floors are uneven. Here are some signs that they are:

  • Do you feel that your underfloor isn’t properly glued and screwed to the floor joists underneath?
  • Does the floor slope?
  • Do you notice high spots?
  • Are any areas of your floor squeaking?
  • Is there movement and bounce when someone walks across it?
  • Are the grout or tiles cracking?

The bathroom floor is damaged with black stains and broken tiles.

Things to know before levelling the floor

Before you start levelling your floor, there are certain things you should consider. Keep on reading to find out all you need to know, so you won’t need to repeat any process.

Identify the Cause

The first step when addressing a sloped concrete floor is identifying the failure cause. This way, you can determine how to repair the concrete or whether you need to replace it entirely. If you notice that the concrete slab has heaved or sunk, it is paramount to address the cause of the failure before anything else. If you don’t, you will continue to run into problems after repairing the floor.

Inspect the material underneath

When you repair floors, it’s essential to examine the type of material underneath. It is often to find void space under a concrete floor due to expansion or settlement of the subgrade. If a frost-susceptible material is bearing the floor, it will be prone to shrinking and expansion

For example, clay can expand in moist conditions and shrink when dry. You should remove the clay and compact a non-frost-susceptible subgrade on top. That way, the new concrete floor will have a solid base to load onto. If the subgrade below the concrete has an appropriate bearing capacity and the concrete is structurally sound, it may only require re-surfacing. In that case, you can just pour concrete on top of the floor.

Safety considerations

Floor levelling is a major project that can permanently alter your home. But before you start your project, it is crucial to make sure you have the right PPE. That includes a mask, safety glasses and gloves. You should be extra careful when taking on any of these DIY projects, and it’s best always to have an assistant help you. 

Step-by-step guide: Preparing the underfloor

Whether you’re going to install ceramic, wood floor, or laminate, one of the most critical steps of any flooring project is to make sure the underfloor foundation is level. The first step is to clean and bond the subflooring before applying the self-levelling screed. Are you ready to tackle your uneven floors? Let’s get started!

Step 1: Remove the existing floor

The first thing to do is to get rid of the outdated flooring material. 

  • With a pry bar, pull up hardwood floors one section at a time. Unfasten the laminate or carpet and roll it up from one end. You will then expose the subfloor underneath, where most levelling problems lie.
  • You may leave sheet vinyl or linoleum in place if it’s hard to remove or if their removal would damage your sub-floor
  • Apply floor levelling compound and bonding agent on top of the existing floor.

a piece of board on tiled floor for removing dirty old trim

Step 2: Check the level of the subfloor

  • To have an idea of how much work you’ve got, set down a 1.8 m level every few cm from one end of the room to the other. A general rule of thumb is that the foundation shouldn’t slope more than 0.50 cm every 3 m.
  • Keep in mind that using a steel ruler or square for measuring the depth of holes or dips is more accurate than a tape measure.
  • If the area is large, use a long, straight 5 cm × 10 cm floorboard and set your level on top of it.  
  • To know how much flooring compound you’ll need to even out the floor, lift the floorboard until it is level.

Step 3: Sand down high spots

Is there any foundation rising above a specified height? You can deal with it by sanding down wooden subfloors using an electric or detail sander. You can also grind these spots with a motorised angle grinder. Remember to wear eye protection and a facemask; grinding and sanding produce a lot of dust

Step 4: Clean and repair old underfloor

Now that the underfloor is free of high spots and exposed, it’s time to prepare it for the new flooring.

  • Fill any cracks in the concrete underfloor with epoxy and ensure that the filled areas are level before cleaning the underfloor.
  • To remove any remaining dust and debris, vacuum the entire room. Then mop concrete underfloor using diluted muriatic acid to clear away traces of wax, oil, or adhesive that may be clinging to their surface.

Step 5: Cover the underfloor with a bonding agent

  • Remember to wear waders, gloves, and old clothing when working with liquid bonding agents and floor levelling compounds
  • Starting with the room’s edges along the moulding, spread on a thin coat of bonding agent with a wide, soft-bristled paintbrush. 
  • Work your way about 30 cm out from each wall.
  • Using a roller or mop, apply the bonding agent to the larger area in the centre.

Step-by-step guide: Leveling the floor

Now that the underfloor is ready, it’s time to apply the self-levelling compound. Ready for a new floor surface? All you have to do is follow our step-by-step guide!

Step 1: Mix the self-levelling screed to a creamy consistency

You will find most levelling compounds in powdered form. That’s why you need to combine them with a little bit of water to be effective. You may also find this product in the market as self-levelling floor resurfacer, self-levelling concrete, or self-levelling underlayment.

  • Pour your powder into a 38 L bucket.
  • Begin adding room temperature water little by little till the mixture thickens to slurry. 
  • Stir vigorously to break up lumps and work quickly; some compounds begin to set up in just a matter of minutes. You can use an electric drill with a mixing paddle attachment to make mixing quicker and more efficient.

Construction worker mixes leveling compound, putties the floor and prepares the floor for parquet laying. The worker mixes the filling floor in the bucket.

Step 2: Pour the screed over the subfloor

  • Start in one of the far corners of the room.
  • Drizzle the wet compound into each of the sunken sections you found while checking the level. 
  • You should pour slowly to minimise any splashes and splatters. The liquid will seek out the underfloor’s lowest parts and fill them in.
  • To make sure that the finished floor turns out flat and nice, it’s best to go ahead and cover your entire surface. You can chip away at what you don’t need later on.
  • Wait and let it work its magic.

Step 3: Smooth out inconsistencies using a hand trowel

By the time you’re done pouring, the compound will have set enough to finish the job by hand.

  • Using long, arcing strokes, spread it over the uneven foundation with the trowel.
  • You should apply a consistent amount of pressure over the whole surface.
  • Focus on contours and lumps where it is possible that the different pools have dried separately and formed noticeable seams.

Step 4: Allow the compound to dry

If you used a quick-set levelling compound, it typically hardens to the touch in a matter of minutes. However, to cure completely, it will typically take several hours. Check the product’s manufacturer’s instructions to find out how long you can expect to wait before finishing your level floor.

Step 5: Sand the entire floor

When the compound is dry, use your electric sander one more time for a perfectly level surface. What you need to do is to shave down slight differences in the subfloor’s height and even out rough patches. 

  • Sand from one room’s end to the other.
  • Reverse your direction each time you reach the opposite wall.
  • Work your way from low-grit sandpaper to a high-grit one to smoothen and blend your floor area.

Step 6: Check the level again

To get a more accurate reading of the overall slope of the floor, place your level in several different spots. The level shouldn’t be off by more than 0.50 cm. Any minor deviations you may discover shouldn’t impact the finished floor’s stability. If your floor is more off level than that, you may need to compound and sand further. 

closeup to a craftsman measuring floor level

Step 7: Install your flooring

Now that the underfloor is level, you can proceed to put in any floor coverings you like without having to worry about any structural imbalances or frustrating gaps. As long as your underfloor is level, everything that goes on top of it will be as well! Some ideas are:

  • Wood flooring
  • Hardwood floor
  • Tile floor
  • Laminate flooring
  • Vinyl plank flooring
  • Carpet 

New plywood underfloor to replace damaged wood

Sometimes, when the problem is minor, all the floor needs are new plywood sheets for the underfloor. If the supporting stringers are in good shape, this will be a relatively quick and easy fix. The plywood will become the new underfloor with the floor laying on top of it. To fasten it down, you’ll need to drill through the wood and into the concrete.

How much will it cost to level your floor?

Are you wondering how much this project is going to cost you? Your favourite answer: it depends! Concrete levelling, in most cases, costs about half of what replacing the entire floor would cost. That makes it a much more budget-friendly solution that can save you a more costly and time-intensive job down the line. An average self-levelling concrete floor will cost around £400-600 per 9 square metres. If you opt for a more luxurious finish and multiple coats, you can expect the price to go up accordingly.

closeup to painting garage floor with brush

Whether you’re going to install laminate, hardwood, or ceramic tile, one of the most critical steps of any flooring project is to make sure your subfloor foundation is level. This project can be a big job during the renovation process. To make sure that you’ll do the job right, check our instructions and get to know all the steps you need to follow. The entire process can take around 2 days to complete from start to finish. After that, say goodbye to cracking, sinking, and sloping and enjoy your advanced floorEven if you want to make cement look like marble, we are here to help you!

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