Condo Blues: Ten Things You Need to Know to Level and Repair an Uneven Floor

Sunday, June 13, 2021

Ten Things You Need to Know to Level and Repair an Uneven Floor

After  I replaced the moldy wood subfloor in my master bathroom, I checked it with a torpedo level (a torpedo level looks like this,) declared it level, and promptly passed out in bed from exhaustion. (Disclosure: I am including affiliate links for your convenience.) The next day, I double checked the new subfloor with the correct tool for the job, a large I-beam level (an I-beam level looks like this.)

The new wood subfloor is not level.

There are a few random areas where the floor isn’t flat, mainly where some of the seams of plywood sheets meet - a pretty common thing when you are replacing a subfloor (especially if it is the first time you’ve removed and replaced a subfloor.)

You can’t lay tile on an uneven floor. Well, you could, but the grout and tile will eventually crack and break in those areas and you’ll curse the day you were born when you have to rip everything out (probably) and do what you should have done in the first place. Fix the uneven wood subfloor with a self leveling underlayment coating for floors.

how to fix an uneven sloping floor

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Leveling the floor stalled my bathroom renovation project because you have to turn off your heating/air conditioning for 24 hours while and after you pour the self leveler. You also need an extra person to mix the compound while you pour it and move it around the room due to its very short wet time – about 10 minutes. With our nutty Ohio spring and summer weather, we had to wait longer than we wanted for the not too cold, not too hot, my husband and I are free the same weekend trifecta before we could get the party started.

How to Do I Level an Sloping or Uneven Wood Subfloor?

How you use self leveler on an uneven concrete floor has the same technique as using a self leveler on an uneven wood floor, only the type of product is different. In my case I have to look for a self leveling compound made for wood floors which requires the extra step of priming the entire floor first.


What I used to level my wood bathroom floor:

Henry Pre-Mixed Floor Patch – You have to fill all of the cracks and seams between sheets of plywood first. If there is even the tiniest sliver or gap, by its very nature the self leveling concrete will find it and drip down into it and make a huge mess.


Floor leveling compound - You can find Henry 555 Level Pro 40 lb. Self-Leveling Underlayment for wood floors here

Electric drill and a mud mixing paddle – I like this mud mixing paddle here

Self leveling compound primer – You can find 554 Level Pro 1 Qt. Underlayment Primer here

how to make throw away work boots

The primer is dry and we're ready to pour!  You may want to invest in spiked flooring shoes like these if you plan to do a lot of this type of work. Since our project is a one and done deal I went with cheap throwaway option. Also plastic bag work boots are wicked sexy!

Paint roller and tray –  if your brand of self leveler requires priming the subfloor first

Spray foam insulation to make cheap and easy expansion joints – Do yourself a favor and buy Great Stuff spray  insulation in a can (you can learn more about Great Stuff spray foam insulation here.) When I used DAP (I like DAP products for everything EXCEPT their canned foam) and Loctite expanding foam insulation for another project it took weeks to harden while Great Stuff always cures overnight.

Cardboard and silicone caulk – you can find silicone caulk and caulk guns here

5 Gallon buckets – do yourself a favor and get at least one (or more) orders of this 6 pack of 5 gallon buckets. You will need them!

Measuring bucket – a measuring bucket like this will make your mixing partner’s life so much easier!

Flooring trowel like this one

Plastic drop cloths – so.many.drop cloths.

Gage Rake (a gage rake looks like this) or a bow rake (I used a bow rake. A bow rake looks like this.)


Self Leveler Tips You Need to Know!


I did a ton of research and watched a lot of YouTube videos before I bought my supplies and leveled my subfloor.  Here’s are a few things I learned that will make your floor repair project easier:


  • Factor in at least three days for this project due to drying times: 
    • One day to prime the floor.
    • One day to spray the expansion joints around the room and allow them to harden.
    • One day to level the floor and allow it to fully harden


  • I removed the bathroom door to make it easier to pour, rake, and trowel self leveler where it needed to go in the room. I cut a piece of cardboard, ran it along the wall with the door frame and caulked it to the floor to make a consistent expansion joint on that wall. The cardboard also acts as a barrier to keep the leveler from seeping out of the bathroom.

how to make cheap easy expansion joints

Hi everyone Lacey the Project Manager here! You should wear a dust mask to protect your lungs from the concrete dust in the self leveling powder. Make sure you put down more drop cloths than you think you need for the mixing area to the pouring area in case of splashing and sloshing.


  • Buy more self leveling compound and buckets than you think you need. When mixed properly the leveler is pretty thin and you may need more in some areas than in others. Keep your receipts so you can return any unopened bags to the store.


  • Yes you really do need an extra person to mix (or pour) because you have about 10 minutes to pour and rake/trowel before the self leveler starts to set and won’t budge. 


  • After I poured a bucket of self leveler I moved between using the rake and the trowel to spread and cover the floor with leveling compound. This worked well for my small bathroom. If you are leveling a larger floor, you may need to run a spiked roller like this kind over the wet self leveling compound to remove any air bubbles that may have formed when your partner mixed the leveler or when you poured it. 


  • Set up your mixing station by measuring and pouring self leveler powder in your buckets and separately measure and pour the water into a second set of buckets. Keep track of your mixing tool and keep it handy. I can’t stress enough how quickly you and your partner need to move during this project.


  • Setting up and cleaning up after will probably take longer than the mixing, pouring and leveling. It took my husband and I about 20 minutes to do the actual mix and pour.


  • Clean your area and tools immediately after you finish. Self leveling compounds are made of concrete and you really don’t want to try cleaning dried concrete from your supplies.

how to use self leveling floor compound cemet
Don't worry if you have swirling or color variations in the dried concrete underlayment. As long as those parts of the floor are hard, dry, solid, and level, you're ready to go to the next step in your project.


  • After you have made sure the self leveling compound is dry and the floor is flat and level, you can remove the cardboard barrier and cut the spray foam insulation level to the floor to make your needed expansion joint. I used this exact Rockwell multi tool because you can use any brand’s blades with it.

Tile Coach’s Easy Self Leveling Underlayment is much better how to level a sloping and uneven floor tutorial than I can write because Tile Coach is s a professional who’s leveled way more floors than I have. If you want to know how to use self leveler to fix an uneven floor check out his video below!


 Looking for more self leveling tools and ideas? Check out the following options – and more! – below!

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Donna Reidland said...

We were faced with that situation once. This is very helpful for future reference.

Life as a LEO Wife said...

This is a good tutorial to file away for that long awaited day when we move in to our house! I bet you got some loud cat calls with those sexy boots and dust mask! Lol. I'd definitely go that route too rather than buy new boots. I'm a miser. Thanks for sharing on Crafty Creators!
Niki ~ Life as a LEO Wife

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