Grinding down basement floor

8 years ago

We are looking at renovating our unfinished basement. The house was built in the 1920s. We have in most spots approx 6’6” height but along the side and in the corners the cement is much highe.

Is is it possible to grind down the high parts by approx half an inch? We’d rather not pour leveller and lose that height - important for my very tall husband, and digging the basement out seem excessive. Can you grind basement flooring down? Is it damaging to the foundation? How would you go about this?

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My Deck

8 years ago

Sorry, I confused your post with another and thought you had the foundation bump out. but, as luck would have it, i had the same issue of uneven floors with some of my1940 basement rooms.
i wanted to not lose height as well, so I tried just patching the low spots and friending down the high ones, and then added floating luxury vinyl tiles on top. however, it was a total failure and eventually, I had to use self leveler to level the entire floor to get it right. although I was scared to lose more height (I had around 7'), I will say that I don't lose more than maybe an inch in most spots. most importantly, I know for sure it's going to give me more comfort and extend the life of my vinyl tiles.
you could though, pay the extra money and remove the existing concrete and put in new.

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Comments (9)

millworkman
8 years ago
No issues doing it but just know that 90 year old concrete will be very hard. The grinding process will make one hell of a mess if if you wet grind it, and it will be time consuming.
ksc36
8 years ago
last modified: 8 years ago
It might be hard getting a permit to create living space with a 6'6" ceiling height.

R305.1 Minimum height. Habitable space, hallways, bathrooms, toilet rooms, laundry rooms and portions of basementscontaining these spaces shall have a ceiling height of not lessthan 7 feet (2134 mm).
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My Deck
8 years ago
you didn't say how much of a bump out this concrete footer is creating. if it's anything like that way it is in my basement, it's probably best to just work that into your designs. if you see my pics below, we just built the wall on to of the footer. depending on the situation, need and budget, you could then build a bench seating or just class the raised concrete with something like an azek board.
Tara Cauchi
Original Author
8 years ago
Thanks for the comments.

I should mention we are in Toronto where the minimu ceiling height for a basement apt is 6’5”
PRO
GN Builders L.L.C
8 years ago
1920's house, concrete is probably 2" thick if that... In those days they only covered the dirt and it was called a "rat slab"...that is what we find here in houses of that era.

The best way is to take the slab out and dig down 12 or so inches and pour a new slab.
SJ McCarthy
8 years ago
GN is on to something here - the slab thickness. I've seen plenty of these old slabs being 'busted open' (for whatever reason) only to discover the thing is SUPER thin (like two inches).

Before you go grinding away, you may need to find out how THICK this thing is. Let's play the "what if" game. What IF this thing is only 2" thick.

I know removing 1/2" doesn't SOUND like a lot, but let's have a look at the numbers using percentages. If the concrete is 2.0 inches, and you wish to remove 0.5 inches, you will be reducing the thickness by 1/4. That's a 25% REDUCTION in thickness. Wow. Imagine what that translates to with an 8" slab...that's the same as removing 2" from an 8" slab. That's a SERIOUS amount of reduction.

The "What if" game is a really cool thing to play. And turning things from inches into percentages REALLY drives the point home.

Please have someone look into the total thickness of this slab before you do anything else. It may not be possible to remove 1/2" for the simple fact that you will turn a thin slab into a paper-thin slab. And a DIY renovation could turn into a money pit if things go wrong.

If you have a thick slab (6" - 8") then 1/2" shouldn't be too bad.
PRO
Knight Kitchens Ed Stoehr
8 years ago
Grinding a half inch of concrete off a basement floor will make a colossal mess. That is a lot of material, the right equipment will be needed so that your entire home with dust and debris.
Jason LeLiever
4 years ago
Any updates on what you did here?