How to level sagging floor in old house using shims, not floor leveler, in home renovation

Renovating an old house inevitably comes with sagging floors to some degree. This time we were faced with 2nd story floors which were out of level. In an effort to add as little weight as possible to the aging floor joists, we choose not to use floor leveler (which is essentially concrete).
To determine actual level, a laser level is a helpful tool in this process as well and can be found on Amazon:
DEWALT Line Laser, Self-Leveling, Red, 3-Beam (DW089K)
by Dewalt

A similar less costly laser level is :
KAIWEETS Self-Leveling Green Laser Level, 360 Laser Line with 2 Plumb Dots, Cross Line 197ft with 7800mAh Rechargeable Batteries & Magnetic Rotating Stand for Construction and Picture Hanging
by KAIWEETS

Rather than using heavy floor leveler, we opted for use of shims to raise the low spots and create a new level surface. When you can't raise sagging floors from underneath, as in this instance, without damaging the ceiling below, the next best option is to create a new level surface from above.

The process is straight forward. We found the highest spots in the room and placed one end of a 6 foot level :
on the high spot and the other end at a low spot. We then used shims (plywood pads) placed on the low spot till the 6 foot level bubble indicated level. Once a wider area was leveled, we could lay down the first sheet of 3/4 inch sub-floor.

Also, if you are in the market for any tools, check out our Amazon store front.
Visit our amazon store front for our recommendations for tools and supplies for DIY success!

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[Housebarons]

We can not stress enough the VALUE of having a laser level when doing this kind of work (or even checking the condition of the floors )!
If you are interested, check out the link :
DEWALT Line Laser, Self-Leveling, Red, 3-Beam (DW089K)
by Dewalt
It works well but this is NOT the most affordable version. We actually have 3 different brands and they ALL work great. If you are looking for more affordable options, check out the video description or our other floor leveling videos in the following playlist :
Just FYI. These Amazon links are affiliate links. They are free for you to use AND Amazon will pay us a small commission if you use them - Many thanks if you do. It helps us keep making videos!

[gregwood]

Great idea! Was just about to rip up my entire floor but I think you've saved me from a massive headache. Thanks from the UK

[JtotheRizzo]

I did this exact same procedure in my 100+ yr old house. A few thought/suggestions if I may:
1. If you have asbestos, it should be removed prior to doing this. If you cover it up, someone else down the line may renovate this house and may end up ripping out the floor and unknowingly disturbing the asbestos.
2. ALWAYS GLUE AND SCREW. Don't use nails.
3. Try to use at least 5/8" thick plywood (3/4" is best) as your top subfloor to maximize strength and minimize bouncy spots.
4. To shim, pick up a few sheets of 1/4" Luan, 1/2", 3/8" and 5/8" plywood. For really bad floors, rip down 2x4 to get desired height. Also pick up wide roofing shims for precision leveling.
5. There should be no more than 8-10" between the shims to prevent that bouncy feeling in areas where the shims are too far apart. If you use 3/4" plywood for subfloor, you can get away with 12" apart.

[bestguy]

I leveled my uneven basement floor with OSB boards, shims and concrete screws. Your video was really helpful. Thank you very much.

[sozaito]

I was planning to do this but started to doubt myself, so it's nice to see confirmation that it will work. You have no idea how you've eased my anxiety. Thank you!

[elvillian]

OMG, this is response to my prayers. THANK

[mariaboice]

This video was just the solution I needed. I have a sloping cement floor we are renovating and putting in new carpet. Thank you so much, I really didn’t want to try self-leveling compound so this looks like a good option.

[cindywatkins]

My sweetheart adjusted some posts under the floor in the crawl space and added some shims to level the floor. Then he used plywood over the subfloor. You need plywood not OSB if you are going to nail down hardwood. Then he nailed down reclaimed red oak with nails and a hammer which we had cleaned and removed nails and staples. Sweetheart then sanded it and used two coats of satin sealer. Beautiful oak floors now. They're fantastic. He did a wonderful job.

[dracula]

I know right away this is quality job when I see oatmeal plywood being used.

[jesserosenbloom]

This video helped me more than any other Ive watched in last couple months. so much appreciated. Thought I was stuck with my sloped floors. will be attempting this today. Im going to put 3/4 cdx ply down as subfloor, then 1/2 backerboard and tile on top. feels like that should be strong enough. thank you again guys!

[SeaTrekkie]

This will be a huge help for me. I have a very wonky floor.

[samjones]

I'm just getting into the remodeling the whole deal and mainly you guys do tremendous good work and I'm just starting and I already made my 10, 000 dollar Mark already just just from watching videos I'm doing jobs I thank you guys have a blessed day man

[timothykentlawson]

I KNEW that there was a way to compensate for an unlevel floor. Thank you for sharing! 👍

[LivPnt]

Omg! I love you!! One of my upstairs bedrooms has a dip in the middle if the floor, and I've been trying to find ways to fix it without major upheaval. This is the best!

[vincentmonet]

Great solution. Cheers chaps. Now to sort my 1830 floor out!

[synovia]

Great video. This is exactly what I thought I could do in my head. Nice to see a visual of it! 👏🏽👏🏽👏🏽

[SGB]

Thanks for the video. One of our bedrooms is like walking in a funhouse.

[john_blues]

Thanks for this. I'm having a house rehabbed and my carpenter just did this and I freaked out a little. lol. His explanation was the same as yours. I'm more at ease now. Thanks!

[carolyncrews]

I am my own diy and my grandmothers bedroom floor is uneven and I need to put down a new floor. Your video is the Best! Thank You so much.

[kashfortheking]

This is a great idea. No way this would fail if the directions are followed. A+ for this one 👍🏾👍🏾