Leveling Garage Slab for New Studio Build

Single car garage slab is sloped- I'm guessing a good 3 inch drop in elevation from one side to the other....going towards the house. House is 20 years old. Hopefully it's done settling! Is there anything I can do to level this thing off or should I just pour a new slab? What are my options? I sign the contract tomorrow on the house. Thanks in advance. I really appreciate your input guys...

I am going to use a combination of mortar and self leveling concrete to level out part of my floor which drops over 1 1/2" in 9.5' Recommended to me by Sandersd in my thread here

Have you ever heard of a mortar bed such as is used under tile? Masons use it to level a floor in preparation for laying tile. It can be several inches thick. My point is it a common practice and is considered by many tile men the best substrate for laying tile. If it works for tile, it'll work for other flooring also. You don't need self-leveling concrete unless you are laying a floor that requires a precisely leveled floor. Just make sure any aggregate in concrete is smaller than the thinnest areas of concrete.

I'm not going to say this is the best way, only 90% sure this is what I am going to do as I've not yet found another option. 1st I'll put down the mortar as flat as can be, then build my inner walls on that. Then drywall and most of the build happens. Then the self leveling concrete just before the wood floor. Self leveling concrete is something like $40 per 60 pound bag and would be expensive by itself for an entire floor... BUT it can be feathered out to an edge unlike regular concrete which needs to be 3 1/2 thick or something like that. To my understanding it's mostly used for leveling, pre installing hardwood floor and other floors which need a very level surface. You can also partially or completely float a wooden deck/float your floor. A search through Google brought me to a DIY leveling a floor technique (please try and find it :D ) which was partial floating. Many PT 2x4's were used, each ripped down to a precise angle, space 16" or 24" on floor and then 3/4" ply on top of that. This technique had nothing to do with studio building. IF you were to do this you would want to fill the voids with insulation or even sand is recommended BUT make sure you read the Floating Floor sticky this forum before even thinking about floating a floor. :D IN my case a mistake by my architect was made, for near the same money I spent on a new footer I could have had a new slab poured and not have to deal with my floor uneven, which part of used to be a patio. Redoing your garage floor would be the best, would cost the most BUT would give you the options of isolated slabs and footers under your new heavier then average studio walls. My wild A$$ guess is it might cost you up to $2,000 depending on how much you can do yourself. I'll be watching this thread to see if any one else has a brilliant idea to level out a conrete floor for a studio. cjbdrm, please when/if you make your decision how to level this, let us on the forum know. Good luck and congrats on the (I presume) home purchase. Marc

Guitardad72, Thanks for the response! I plan to start my own studio build thread when the time comes... My next question will be 'to beef or not to beef' (the outer walls of the garage): From what I understand, the 3 leaf effect applies mostly to smaller sealed airspaces, is this correct? So if I build a 'room within a room', and have a good deal of air surrounding that room, wouldn't that negate the 3 leaf effect? For instance, if the dimensions of the garage are 10' high by 11' wide by 21' long, and the room I build is 8' high by 9' wide by 16' long, that's a difference of 1158 cubic ft. of air. Surely that volume of air can't be acting as a 'spring' can it? I'm sure that certain conditions must be met to create the 3 leaf effect- my question is whether or not this scenario would meet those conditions.

I'm going to advocate breaking up that old slab and pouring a new one because that's what I did and misery loves company. :twisted: But seriously... It is the ideal (albeit expensive) solution. Sloping 3" towards the house? YIKES! :shock: --Keith :mrgreen:

sharward wrote:

I'm going to advocate breaking up that old slab and pouring a new one because that's what I did and misery loves company. :twisted: But seriously... It is the ideal (albeit expensive) solution. Sloping 3" towards the house? YIKES! :shock: --Keith :mrgreen:

I was afraid you'd say that! It might be 2 1/2"...but it's definitely noticable. Maybe my biggest worry should be the house falling into a sinkhole! But like I said, the house is 20 years old, so I'm hopeful it's done settling. Maybe I should bring someone in to look at the slab? I guess during house inspection, I could ask about it? It's doubtful the garage slab is being used to support the house, right? But it looks like it the way it's sloped towards the house. Well, any help is appreciated. I don't want to make a very big expensive mistake.

Maybe I'm making too many assumptions. The direction of the slope should be towards the big garage door so that melting ice/snow or any such thing runs towards (and out) the door. If it's sloping the opposite direction, then you have a serious problem! If your garage slab is monolithic and sloping the wrong way, then it's possible the entire garage is leaning like a certain infamous Italian tower... :roll: Get a whole house inspection, quick!!! Never buy a home without one! --Keith :mrgreen:

Absolutely. Home inspection is in 10 days. If there are any issues, there will be some re-negotiating :) I did find the IRC 2003 309.3 code snippet regarding garage floors sloping towards a drain or the door opening itself...I didn't see a drain... A softball placed on the floor in the back left hand corner of the garage rolls indirectly towards the house, with maybe a 20 degree angle towards the garage door opening. To me, it's significant. It''ll probably pass inspection and I'll have to deal with it, unfortunately. These people have all their belongings in the garage. I can't exactly pour water on the floor and see where it goes... Anyone have any experience with this? Any inspectors in the house?