# Leveling concrete floor of garage



## jovol (Sep 28, 2015)

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


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## MT_Stringer (Jul 21, 2009)

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


Better check with the person you are renting from first.


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## a1Jim (Aug 9, 2008)

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.


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## waho6o9 (May 6, 2011)

There's supposed to be a slope for drainage.

And a belated welcome to Lumber Jocks Jovol!


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## jovol (Sep 28, 2015)

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


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 (Jun 5, 2015)

> 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


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## jovol (Sep 28, 2015)

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?


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## rwe2156 (May 7, 2014)

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.


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## jovol (Sep 28, 2015)

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?


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## canadianchips (Mar 12, 2010)

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 !


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## Finn (May 26, 2010)

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.


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## WoodNSawdust (Mar 7, 2015)

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


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## AZWoody (Jan 18, 2015)

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.


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## Hammerthumb (Dec 28, 2012)

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.


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## MT_Stringer (Jul 21, 2009)

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.


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## Bluepine38 (Dec 14, 2009)

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.


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## jovol (Sep 28, 2015)

Hey all,

Thank you for all your opinions. I decided toward the sleepers + osb option as it was cheap, and easily removable should that ever need to be done. It has been a lot of work, mostly in shimming all of the sleepers to sit flat. Here are some picture updates:

(layout) http://i.imgur.com/51LncPu.jpg
(half the sleepers done) http://i.imgur.com/OynF4ng.jpg
(3/4" OSB laid out) http://i.imgur.com/ZmJQa5K.jpg

the sleepers are 16" on center, with support shims placed every 16". The edge shims are drilled into the concrete, in addition to the rails, but the interior shims are simply screws to the sleeper.

This upcoming weekend I am going to finish up the last few sleepers and install the moisture barrier and OSB.

I am trying to decide if I want another layer over the OSB. The OSB definitely feels strong enough, but the pressure/wear-and-tear of the jointer and table saw on casters has me worried. Visually, the OSB is a bit intense. Do yall have an suggestions for a top? I have in mind a cheap plastic light-colored laminate, and then covering that with epoxy. Does that sound doable?

John


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## MarkTheFiddler (May 29, 2012)

Howdy Jovol,

I'm just answering a question you asked earlier. I used the self leveling concrete on my kitchen floor before I tiled. I got as much as 1/2 inch thick in a few places while the higher spots just seem to be glazed over. I'm pretty sure it's the fastest route to go. There are lot's of videos online that tell hour to prepare and pour.


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## jovol (Sep 28, 2015)

Hey Mark, thanks for the suggestion. Unfortunately, my height differential was about 5" from one corner to the next.

Cheers,
John


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## bandit571 (Jan 20, 2011)

One other tip when using the sleepers. the space between them can be fill with a foam board, makes for a warmer floor under foot.

On top of the OSB, use an "Underlayment" plywood. It is just a 1/4" thick Luann, but designed to act as underlayment for flooring. Run the joints @ 90 degrees to the OSB. Then Paint the Luann.

use the THICK, Tongue& Groove OSB helps.


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## jovol (Sep 28, 2015)

I messed up! I accidentally bought non-t&g osb. Fortunately it's not a big deal laying something like 1/4" underlayment perpendicularly on top. I think i'll do that, paint it, and coat it in epoxy  Thanks for your advice!


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## rwe2156 (May 7, 2014)

Bummer about the plywood. T&G is definitly much stronger but probably still ok.

They might make an H clip but I don't know if for 3/4.
Or you can scab a 1×4 underneath to cover both seams.

Other suggestions/observations:

I would want a moisture barrier and maybe insulation (depending on your climate).

Epoxy is quite an expense, no? I would suggest painting with several coats of porch paint should be adequate.

Underlayment is going to add enough cost that I would be very tempted to exchange the OSB for sanded pine T&G ply. You will have a better floor in the long run for just a few dollars more. Not like you're looking at 20 sheets, right? You can even forgo the paint and leave as is maybe a couple coats of wood sealer.


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## jovol (Sep 28, 2015)

Hey all!
As a way of closing up this thread, I thought I post my finished floor. It ended up being non-t&g 3/4" OSB finished with three coats of polyurethane. It has certainly been strong/dense enough to handle rolling my table saw and jointer around. We'll see what happens when I start dropping things. It reflects a wonderful amount of light, especially considering the lighting it lacking in the shop. Here are some pics of the finished floor, and the hinged ramp I made for rolling heavy things in. It is certainly not perfect, but the subtle "bounce" is actually quite nice to walk on. I've left the left edge of the floor unfinished now in case I want to run things under the OSB, but will likely just cover that with OSB when I get the time.

sleepers done, plastic getting nailed down:


http://imgur.com/lpn6e2v

OSB laid and polyurethaned:


http://imgur.com/rSMHPe1

all the tools inside 


http://imgur.com/CqqOsD4

ramp up so I can close the doors:


http://imgur.com/VewM1lI


Even without insulation under the floor, the room is much warmer, esp for San Francisco's temperate climate.

If you have any questions, feel free to ask!


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## emanjamin (Nov 18, 2015)

I want to say thank you very much for starting this link and posting pictures! 
I am kinda of hijacking /opening the thread back up since this will somewhat relate.

Complete and very new rookie to this whole woodworking thing so bare with me. 
I have a rather large "barn" that I am trying to turn into a wood shop, it is a two and a half car width and easily two car depth. I also have a sloped floor to the center where I have a drain tile installed. Currently I have my bench and table saw leveled with wood blocks (poorly constructed) and I have numerous other tools I want to have a permanent place for but have qualms about the space available and what layout I should use… The entire left side is open to play with with a installed wood stove in the back left corner. The right side has chickens, and I will need to fit my vehicle with a plow among other lawn tools (tractor), patio furniture, and things a "normal" garage has in it. So the entire right side is off limits.

So my focused questions for this thread are, how should I level the floor, if I am going to (I am thinking that a concrete leveling compound would defeat the purpose of having the drain tile in the middle); Should I just keep using blocks of wood to keep everything level and find a spot to keep everything and not having it mobile. If I go the way that Jovol went, do I need to use the vapor barrier and polyurethane? I already have a snow plow = (lots of extra moisture) and chickens constantly breathing and pooping (necessary, and lots more moisture). I am thinking that I don't need to since I am not worried about moisture coming up from the concrete or any flooding. 
Also, if I am going to build a sleeper floor as shown, should I do just enough to level it and that is it, or should I really raise it up and possibly have all my DC piping and power run under the floor?!? I think I have a 12 foot ceiling so raising the floor wouldn't be an issue except for the cost and the fact I have no idea how to do it….
I know that I have some premium real estate for a wood shop this large, but I have no idea how to lay it out. We can save those responses for a whole new thread ;-)
I will try and take actual measurements tonight and take some pictures of what is currently in there now. 
I thank you for all who read this and post an opinion. I just want to do this efficiently from the beginning without going completely overboard.


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## Finn (May 26, 2010)

Something to consider. I routed my dust collection duct (6") along the floor against the wall and located my equipment near this duct. This eliminates the length of duct it takes to get up to the ceiling and then back down to each inlet. Under floor would work like that also.


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## emanjamin (Nov 18, 2015)

I had actually done something very similar to that before aquiring all of the other tools other than the portable tablesaw. 
One thing I forgot to mention is that my DC is now located upstairs in a sound dampened box. I figured that it would be better if I had length going from tool up to the ceiling, then over to the DC already in located up so I didn't have to run duct back down to valuable floor space. 
PS: pictures are coming as soon as I figure out how.


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## emanjamin (Nov 18, 2015)

Ok, here are 4 pics of the general layout now. Please be gentle with the judging . I have a lot of junk in there!





































I don't know why the first two images rotated… They didn't rotate when I took them. Unless it is my phone…


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## NDakota (Mar 2, 2014)

With that little slope why do anything? Your tools dont know the difference and after awhile you wont notice. There is a difference between flat and level! They only thing I would level up is workbench and shelving.


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## emanjamin (Nov 18, 2015)

> With that little slope why do anything? Your tools dont know the difference and after awhile you wont notice. There is a difference between flat and level! They only thing I would level up is workbench and shelving.
> 
> - NDakota


Ah, I have actually wondered that too. After browsing the internet, I kept finding all these articles about level floors and marking the floor exactly where you level spot is so your tool will always be in the right level to work with should you move it. 
How necessary is level? Flat totally understandable but level?
From the wall to the edge of the workbench (about 36in and there is about a two in difference. So going all the way to the drain, it has to get pretty significant.


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