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Leveling concrete floor of garage

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Forum topic by jovol posted 10-15-2015 01:45 AM 1207 views 0 times favorited 28 replies Add to Favorites Watch
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jovol

12 posts in 438 days


10-15-2015 01:45 AM

Topic tags/keywords: concrete floor workshop level flatten

Hi there LJ!
First post. Recently started renting a garage/shed space in Sf that I’m making my woodshop. Before I set up the machines in the space, I want to take care of the shoddy concrete floor. There are divots and cracks in the concrete, and it has an annoying slope towards the door. It has made it difficult to wheel around my table saw and jointer.

I’m asking for advice on how to deal with this. Should I lay new concrete? Create a wooden floor? Perhaps some of you have dealt with this before.

The space is 18’ x 8’.

Thanks,
John


28 replies so far

View MT_Stringer's profile

MT_Stringer

2854 posts in 2697 days


#1 posted 10-15-2015 02:31 AM



Hi there LJ!
First post. Recently started renting a garage/shed space in Sf that I m making my woodshop.

Thanks,
John

- jovol

Better check with the person you are renting from first.

-- Handcrafted by Mike Henderson - Channelview, Texas

View a1Jim's profile

a1Jim

115202 posts in 3044 days


#2 posted 10-15-2015 02:48 AM

Welcome to Ljs John
It’s pretty unusual for a renter to go to the expense to level a floor for the owner. There are a number of ways #1
buy some self-leveling concrete and read the instructions how to use it #2 use sleepers( strips of wood that are cut at an angle to counter the slant) and then apply sheet goods over the top of the sleepers,#3 hire a company that has a diamond grinder and have them grind it level.

-- http://artisticwoodstudio.com Custom furniture

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waho6o9

7179 posts in 2043 days


#3 posted 10-15-2015 03:08 AM

There’s supposed to be a slope for drainage.

And a belated welcome to Lumber Jocks Jovol!

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jovol

12 posts in 438 days


#4 posted 10-15-2015 03:16 AM

Hi there LJ!
First post. Recently started renting a garage/shed space in Sf that I m making my woodshop.

Thanks,
John

- jovol

Better check with the person you are renting from first.

- MT_Stringer

I’ve asked my landlord and she is okay with me doing so. This is an outdoor shed/garage in well-used condition, and she is open to any rehabilitations I do. Unfortunately supply of such spaces is on the low side in SF.


Welcome to Ljs John
It s pretty unusual for a renter to go to the expense to level a floor for the owner. There are a number of ways #1
buy some self-leveling concrete and read the instructions how to use it #2 use sleepers( strips of wood that are cut at an angle to counter the slant) and then apply sheet goods over the top of the sleepers,#3 hire a company that has a diamond grinder and have them grind it level.

- a1Jim


The self-leveling route sounds doable and robust. How thick can a layer of this go? The difference in the low-side to the high-side is about four inches. With all my recent woodworking tool purchases, it would be nice to use them for this process. The only part of the wooden floor fix I’m worried about is the height delta between the floor and outside, making it hard to wheel machines in.


There s supposed to be a slope for drainage.

- waho6o9


That’s a valid point. There likely should be some sort of mild slope. However, the current floor is very uneven and “warped” (presumably sunken over the years). However, I don’t think a drastic slope for a shed that shouldn’t be draining anything is intentional.

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ForestGrl

445 posts in 553 days


#5 posted 10-15-2015 04:23 AM


The only part of the wooden floor fix I m worried about is the height delta between the floor and outside, making it hard to wheel machines in.

Is there room outside the door to install a ramp that will solve that problem? Seems like no matter which method you use, that end of the shop is going to be 4” higher than it is now. :-0

-- My mother said that anyone learning to cook needed a large dog to eat the mistakes. As a sculptor of wood I have always tried to keep a fireplace. (Norman Ridenour)

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jovol

12 posts in 438 days


#6 posted 10-15-2015 04:50 AM

Good point. There is room I could add a ramp. The sleeper+plywood floor does seem the least invasive and probably cheapest route! Not to mention I could take the materials with me whenever I leave this space.

Is there special plywood to use for flooring? And what should be the thickness be?

View rwe2156's profile

rwe2156

2198 posts in 947 days


#7 posted 10-15-2015 10:54 AM

I don’t think a thin layer of concrete will stand up to rolling machines.
It would have to be at least 2” thick, IMO.

I totally agree with Jim re: plywood.

I would definitely use 3/4 and I would check into the tongue and groove ply made for subflooring.
We have a product around here that is a waterproof strand board that is excellent and quite reasonable cost.

Good luck I think it will be a worthwhile investment and make the shop much better to work in.

-- Everything is a prototype thats why its one of a kind!!

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jovol

12 posts in 438 days


#8 posted 10-15-2015 11:04 AM

Something like this?
T&G Oriented Strand Board 8’ x 4’ x 23/32”
http://www.homedepot.com/p/Unbranded-T-G-Oriented-Strand-Board-Common-23-32-in-x-4-ft-x-8-ft-Actual-0-703-in-x-47-75-in-x-95-75-in-920924/100054132
... this is actually way cheaper than I expected.

Would this be fine without any other layer atop it?

View canadianchips's profile

canadianchips

2360 posts in 2464 days


#9 posted 10-15-2015 11:48 AM

I would be concerned about any plywood or especially strand board laying directly on concrete. I would use pressure treated sleepers to level floor first, then a subfloor made for moisture or even 5/4 pressure treated deck boards. Also ask yourself: How many critters and bugs are going to move in under this gap in the floor ? Maybe layer of self leveling concrete will solve a lot of future problems .
Check prices on product called DRI CORE. Comes in 2’x2’ panels, made to lay direct on concrete. Can be removed easily if something goes wrong in future (like flooding)
These are just my thoughts !

-- "My mission in life - make everyone smile !"

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Jim Finn

2417 posts in 2388 days


#10 posted 10-15-2015 01:09 PM

I had this problem and solved it by ripping 2×4’s to different widths to level the finished floor and screwed them together and screwed tongue and groove plywood over it. (Not anchored to the floor) When I moved I unscrewed all of this and took the floor with me, and installed it in my new shop. I knew where the heaviest equipment would be and put the ripped 2×4’s 12” on center there.

-- "You may have your PHD but I have my GED and my DD 214"

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WoodNSawdust

1417 posts in 643 days


#11 posted 10-15-2015 01:36 PM

You might want to look into sprays and/or powders for insect control. Put them down before you add the plywood floor.

-- "I love it when a plan comes together" John "Hannibal" Smith

View AZWoody's profile

AZWoody

697 posts in 690 days


#12 posted 10-15-2015 03:37 PM

This can turn into a pretty big and expensive project.

You can get self leveling products for floors, but they’re not meant to be the top coat. In the areas where it is not thick, it will eventually crack and come off the floor. They are meant to level the floor before putting in the final flooring, whether it be carpet, tile or hardwood.

You could also put the self leveling material down, then build a floating floor out of plywood with some 2×4 or similar support underneath so the plywood will not lay directly on the concrete.
I would stay away from the OSB. It will work under carpet or something like that but will not stand up very well to machinery rolling around or will also separate or swell with water spills or leaking from rain.

If you’re wanting to just fill holes, you can try some concrete and mix in some concrete adhesive and apply the adhesive to the floor also. We have done it in a shop we have here but it only is good for some of the deeper holes. If it’s shallow, it won’t stand up to too much rolling around on it.

View Hammerthumb's profile

Hammerthumb

2533 posts in 1442 days


#13 posted 10-15-2015 03:53 PM

Most self leveling products like K-15 Ardex have limitations on how thick they can be applied. Also, how high a lift (single poor) can be done at a time. I believe that an aggregate will be required for anything over an inch. Self leveling products are very expensive and tempermental when it comes to application.

If you are going to do this with a cementitious product, look into using a product like Paragon Deck Mud to do the actual slope correction. Basically it is a sand and Portland cement mixture that will give you about 1” over 10 sqft for less than $5. A self leveling pour can be applied over the top of that.

-- Paul, Las Vegas

View MT_Stringer's profile

MT_Stringer

2854 posts in 2697 days


#14 posted 10-15-2015 06:56 PM

Sometimes, I get lazy, and this would be one of those times! Instead of all the work required to level/flatten the floor, I would get a quote or two from a concrete guy to pour a floor with some reinforced steel in it.

This would be a simple job for someone who does it for a living, and they have the tools and skills to do the job right the first time.

I don’t know if a permit would be required, but you could ask someone that knows.

-- Handcrafted by Mike Henderson - Channelview, Texas

View Bluepine38's profile

Bluepine38

3341 posts in 2552 days


#15 posted 10-18-2015 07:50 PM

A lot of concrete floors cracked because the dirt underneath them was not compacted properly, this could
cause problems with any floor poured over the top of the old floor, as MT_Stringer suggested above, you
should ask an expert that knows more about concrete floors than us. It might cost you, but maybe not as
much as having to redo a mistake.

-- As ever, Gus-the 77 yr young apprentice carpenter

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