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Evening Concrete Slab

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Nov 29, 2013, 11:59 PM
Evening Concrete Slab
My husband and I are pulling up all the carpet in the main living areas in our house. The previous owner turned the back patio into a huge sun room. There is a slope leading from the living room to the sun room. It is a slope of 2 inches over about 4.5 feet. Would it be easier to use our circular saw to cut a 2 inch line and break the concrete on that line and make a mini step between the two rooms or should we use self leveling concrete to help smooth the slope so that it feathers out over a larger area so that it doesn't affect the flooring?

We are hoping to do it cheaply because we just spent over 1k on supplies to redo the floor.
Nov 30, 2013, 11:12 AM
Easy answer: It is almost impossible to cut out the wedge of concrete needed to make a level floor with a 2" step. You are far better off to raise the floor to make it level. A couple of ways to do this:

1. Pour in a self-leveling cement to add the extra 2" to tapered amount needed. Pros: Fairly easy to do, just make a liquid mix and fill the space. Cons: Depending on how much area you have, you can run up some money in material. If your ceiling height is already low, you will lose another 2" of height.

2. Cut tapered joist pieces that are glued to the existing slab to level it out. Then, install a 3/4" wood subfloor. Pros: Can be as affordable as leveling cement. Once installed, the wood subfloor allows a wider variety of finished flooring products. Cons: More labor intensive. Higher skill level needed for a level install.

Nov 30, 2013, 01:45 PM
The backroom is around 500 square feet so its pretty huge. That's why we were hoping to remove the slope rather than try to raise that much floor.
Nov 30, 2013, 03:07 PM
The only way you could remove the concrete would be to rent some kind of commercial concrete grinder. Not even sure if you can rent one but even so, you will be grinding a taper from 2" to nothing - very difficult to do. I expect that even if you do grind the surface down, you will then have to do a pour to get it back to level.

That's a big area! If you did a pour to bring it up by 2" on the low end, then (if it's a 50' x 10' area) you will need a total of 72,000 cubic inches of mix. That's around 50 eighty-pound bags. The cheapest thing out there that will taper to 0" is thinset, so you are looking at around $500 of material to do the fill. Note that those numbers are approximate from the details given here.

Nov 30, 2013, 11:48 PM
$500 is certainly NOT an option for us financially at the moment.

If we used the circular saw set to a depth of two inches is there any way to use a combination of hammer and grinder to make it even enough. Keeping in mind with laminate it doesn't have to be perfectly flat just flatter than what we have!

I also read that we might be able to level it out enough with plywood. If we could make the 2" inch height of the slope angle out a farther distance (like across a larger portion of the room say over 5 or 6 feet) then it would be a possibility for us to still use the laminate.

This message has been edited. Last edited by: RobertsKitty,
Dec 01, 2013, 05:47 AM
What are the exact dimensions of the area that you want to level? If you post that, I can give you a more exact idea of what you are in for.

HOWEVER - From what you have said so far I have to tell you that what you want to do is just not going to happen. If $500 is way out of your budget range to level a 500 SF area of concrete slab, then you just can't do the job. I know you don't want to hear this but I am a contractor, I've done this kind of work for years and I do know what I am talking about. Some basic facts:

1. A circular saw will not cut 2" into concrete. Sure, given a circular saw and some masonry blades or even a diamond blade, you could eventually make a plunge-cut to a depth of 2" in concrete. Given an afternoon, you may be able to make a 2" deep cut that is a couple of feet long. But you will not make it much further than that. A typical circular saw is just not powerful enough. If you try to make a long and deep cut in concrete with a circular saw, you will soon burn the saw out. Plus, you will chew up a bunch of masonry blades. Even if you sprang for a better diamond blade for an extra $40 to $50, you will find that a small blade of that size will soon overheat, warp and lose it's temper. You just can't make big cuts in concrete with a typical circular saw.

2. You will need what's called a quickie saw. They look like a chainsaw with a 14" round cutting blade instead of a chain. They are available to rent at around $50 a day plus the cost of at least one 14" diamond blade at around $100 or more. They come in both gas and electric, but the gas versions cut much better.

3. All this is really a moot point though - Cutting a 2" deep line will not do much to level out the slab. Concrete is very strong and you are wanting to cut out a tapered section. To do this you would need to make many cuts in both directions so that you could divide up the slab into about 2"x2" squares. These smaller squares would then need to be manually chipped out. Your cuts would have to be of varying depth as you moved across the room. Even with a bigger saw, this will take you a long, long time and at the end you will have a very rough surface that will still need to be leveled.

4. Basically, even with all the right equipment it is not an option to cut out the concrete that you want to go away. In short, you will spend more to try to remove the old and build it back up than you will with a more simple overlay method.

Post the actual dimensions of the area and I can give a more accurate material cost to help you decide if you can do this. Your best options remain either of the two methods I listed in my first post above. Even with all DIY labor, this is a big job that requires tools and materials - I strongly feel that even a $500 budget will not get it done.

Dec 01, 2013, 09:35 AM
And if that slab is only 3 1/2 inches thick, cutting out 2 inches is not a good thing, and not to forget about any rebar in that slab or whatever was used (if used).

And with the dust and noise to cut out the slab, most DIY people will quit after they get about 1 foot of it done. "there's got to be a better way"

This message has been edited. Last edited by: Re-mdlr,

They make it look so easy on tv, don't they
Dec 01, 2013, 12:20 PM
I've seen on some of the home improvement shows like TOH when they do a hydronic heat install they'll pour a thin layer of concrete over the top, coming in from a Redi-Mix truck. It has no aggregate or only sand for aggregate and is very runny/self leveling. Cost aside would this be a valid option for the OP rather than mixing up individual bags of self leveling mix?

In leveling 500 square feet it is probably on the upper end of possibility for bags of mix and low end for a redi-mix truck.

General Disclaimer

Any advice given here is general in nature and is not necessarily valid for your given area. If in doubt check with your local codes enforcement department for what is required when doing electrical, plumbing or structural work on your house. Permits may or may not be required in your area and home owners may not be able to DIY some tasks. I have no way of knowing if you have the skills needed to complete the tasks you are asking about, when in doubt seek professional assistance.

My advice may be worth exactly what you pay me for it. :-) For the record I did not stay in a Holiday Inn Express last night.
Dec 01, 2013, 01:28 PM
Sparky - The OP stated in their original post that cost was a definite factor so I was trying to address the least expensive ways to level the floor. The entire area needs about 1-1/2 cubic yards of masonry fill - this is an awkward amount as it's near the high end for mixing individual bags yet is below the minimum delivery amount for redi-mix places.

Using thin-set is the least expensive product available - general purpose thinset goes for under $10 for a 50 lb bag. The thinset has the ability to feather out to almost nothing yet it can also fill the 2" deep areas. It's weakness is in those deeper areas as it is a softer product than other types of 'concrete'

There are better leveling cements out there that feather out even better than thinset but a product like Soniflo or the equlivant will cost in the area of $30 or more per 50 lb bag - pushing the material costs to over $1,500.

They could probably do better with a redi-mix product of leveling cement mixed with a fiber reinforcement. This would make for a strong pour that can feather out. Just guessing but as a more costly product and having minimum load surcharges I would expect around $1,000 for the small load needed. Plus, with redi-mix, you still have to get all the product from the truck to the site quickly or run extra time charges.

I think it's all moot at this point though, it's a big project that will have significant fixed material costs. As RobertsKitty has stated that even $500 is way beyond their budget, the best advice we can give at this point is to advise on the best plan to save up for.