I give up.... time to replace my garage slab

cbracer · Mar 16, 2013

I've got 3 days of work into prepping and fixing my old garage floor in hopes of doing porcelain tile over it, and now I'm over it. In my 20x20 garage, there's about 60 feet of cracks, delamination within the concrete, efflorescence, and very much not flat or level. I power washed it yesterday and now looking at it I just can't see it worth fixing.

I calculated $800 alone in leveling compound. Then a decoupling membrane for 400sqft which would be another $600. Fixing the cracks with good stuff will be another $200. Proper tile grinder rent or buy $150. Tile another $600 + thinset $300. That's $2700 and days more work when I can get a new poured concrete for $3200 and not have to do the work myself. Sure it won't be tile, but there more I can do with good concrete than bad stuff.

Any pointers for a new slab I should watch out for?

HotrodHR · Mar 17, 2013

There's got to be an easier fix than a complete repour. You're going to have to jackhammer that floor out and haul it away... I doubt the concrete guys are going to do that plus lay new floor for $3200. Better check the price...

pauloman · Mar 17, 2013

one or two coats of a solvent free epoxy floor coating would solve 90% or more of your issues and cost about $400-$500 - something like Industrial Floor Epoxy (tm)

miketyler · Mar 17, 2013

Hard to tell from pic but do how much elevation variation do you have?

cbracer · Mar 17, 2013

pauloman said:
one or two coats of a solvent free epoxy floor coating would solve 90% or more of your issues and cost about $400-$500 - something like Industrial Floor Epoxy (tm)

A neighbor down the other street tried that and it cracked in less than a year. If you have cracks of any decent size, a thin coat of epoxy will just crack with the concrete. Besides, my biggest complaint is how un level the floor is. Putting my tool box against the wall and the drawers slide open because it's so un level especially on the perimeter.

cbracer · Mar 17, 2013

HotrodHR said:
There's got to be an easier fix than a complete repour. You're going to have to jackhammer that floor out and haul it away... I doubt the concrete guys are going to do that plus lay new floor for $3200. Better check the price...

Hauling out the old stuff is included in the price if they can get a bobcat in to break it all out. Unfortunately they can't cause the ceiling is too low. So now it's $3800 for them to take the concrete out or $2800 if I take out all the concrete. Previous quote from another guy was $4000. I've got a full inch of un levelness, so leveling compound is too expensive.

My only hope would be MG-Krete poured over the top. I'm investigating that again first before pulling the trigger.

Shea · Mar 17, 2013

Have you considered filling in the low spots with a self-leveling polymer floor coating and then going with interlocking tile or floor mats? That's what is nice about a full floating floor covering. You don't have to worry nearly as much about prepping your floor like you do for porcelain tile or a coating.

TommyK · Mar 17, 2013

cbracer said:
Any pointers for a new slab I should watch out for?

Re-grade and re-compact the base. Install vapor barrier. Wet cure it.

cbracer · Mar 17, 2013

Shea said:
Have you considered filling in the low spots with a self-leveling polymer floor coating and then going with interlocking tile or floor mats? That's what is nice about a full floating floor covering. You don't have to worry nearly as much about prepping your floor like you do for porcelain tile or a coating.

Oh yeah, looked seriously at the tuff-shield tiles because I don't like plastic floors. But the leveler would run $800, plus fixing the cracks or it will continue to move and be unlevel again so another $200, plus grinder/dust sheild/diamond cup $200, plus the plastic floor. The leveler and primer won't stick, that's already been tried on a house 2 doors down. Which is when I decided leveling isn't going to work. Plus there is a 2" grade back to front so it can't really be level. Maybe dump $400 of leveler and see where it comes out to? But the perimeter is curled up and nothing can go along the wall without a good 4-5 degree slant

Had a concrete guy out today who has been doing this area for 50 years. He said the alkalide in the soil eats away at the concrete used in the 60's. It wasn't till late 70's they figured it out and changed the mixture to fix it.

guess if I want it level then bite the bullet and spend the money....

Todd.Brock · Mar 17, 2013

If you hate it that much, it sounds like you are skirting around the only real fix! Good luck and you know it will be exciting to have the new floor. Imagine your tool box drawers not opening them selves!! If I read correctly, 1000 bucks to demo? Do y have a way to haul it, and dump? That would be next to impossible without a truck and trailer. You could rent the jack hammer for 100-150 bucks, and then dump fees? How much is your time and back worth?

Herb67SS · Mar 17, 2013

I'd go with the $3800 and have the floor I want. Sometimes you don't really save money in the long run by going the cheaper route. Besides, that demo is a killer for a weekend warrior. Just make sure you and the contractor are on te same page on EVERY detail, I.E. wire/rebar, fiber, thickness, leveling and compacting the base, vapor barrier, etc. etc. then monitor the job closely to insure you are getting what you expect. Let t he contractor know you are just trying to make sure the end product is what you expect cuz you are the one that has to live with it, not him. Most good contractors understand that and will respect your involvement. Mine did on my new 28x36. Had a good contractor, did a great job but I still caught some gaps in some details that didn't get communicated properly to the workers. Not unusual. This wasn't his only job, but I was my only new garage build.

cbracer · Mar 17, 2013

Todd.Brock said:
If you hate it that much, it sounds like you are skirting around the only real fix! Good luck and you know it will be exciting to have the new floor. Imagine your tool box drawers not opening them selves!! If I read correctly, 1000 bucks to demo? Do y have a way to haul it, and dump? That would be next to impossible without a truck and trailer. You could rent the jack hammer for 100-150 bucks, and then dump fees? How much is your time and back worth?

Thanks, and you're right I should put a new floor in cause there's no way to level what I have. There's a recycle place for concrete at $35 per truck load and 20,000 lbs would be 15-20 trips so $600, or a low box from the dump is $500 plus two trips so $70 as the low box won't fit all of it. Then rental of the jack hammer and time to do it, plus getting friends to help which means likely only on the weekends. For $300 more I could go to work for the day and let other people do it. If the dump fees didn't exist and it wouldn't take so many truck loads, sure it would be better to do it myself. The guy I'm talking to is pretty honest about all the costs and where it goes.

cbracer · Mar 17, 2013

Herb67SS said:
I'd go with the $3800 and have the floor I want. Sometimes you don't really save money in the long run by going the cheaper route. Besides, that demo is a killer for a weekend warrior. Just make sure you and the contractor are on the same page on EVERY detail, I.E. wire/rebar, fiber, thickness, leveling and compacting the base, vapor barrier, etc. etc.

Yeah I'm torn on the vapor barrier. It creates surface cracks when the concrete drys, but prevents moisture coming up through afterwards which is only needed if you have coverings that later peel off. The dirt has all the alkalides so I'm leaning towards gravel / sand underneath and forgoing the vapor barrier since they don't use them in southern California.

I'm going to add wire to hold the concrete together if cracks form. Rebar is overkill for my simple garage. 3000psi concrete.

James-W · Mar 17, 2013

I agree, busting up the old concrete and getting rid of it is back breaking work, not to mention it can be expensive to get rid of the old concrete. I would not recommend trying to do it yourself, even if you have some friends to help you.

From looking at the pictures of the old concrete, I agree with you, I would say it is time to get rid of the old floor and pour a new one.

I would, however, suggest one more thing. If, at some point in time, you are plan on putting down some sort of floor covering, then do it right away after the new floor is poured. Do not wait until you have all sorts of stains on the floor before you decide to do something with the floor.

Herb67SS · Mar 18, 2013

Nothing wrong with wire and fiber in the concrete. Helps stop cracks from running even if you get some (which you shouldn't). I have a 24x24 attached and no expansion joints with no Cracks in 17 yrs. I see you are in SoCal. You shouldn't need any.

dcs Inc · Mar 18, 2013

Replace it. No type of lipstick will change this pig. The concrete is beyond it's life cycle. Also have some crack control cuts placed at time of pour. Concrete shrinks during hydration and the control cuts will insure no random cracks.

This is a one day project for a concrete crew to tear out and replace. If you have a concrete drive, have them wheel barrow from the street. Don't pull the concrete truck on the driveway.

Compacted sub base, low slump, 4000 psi + mix design, minimal 4" thick. If parking heavy trucks on it go 6".

roblouvasz · Mar 18, 2013

I can't tell from the photo but do you have an existing floor drain? If not, have you considered putting one in the center with the floor sloped towards it? Just a thought.

cbracer · Mar 18, 2013

dcs Inc said:
Compacted sub base, low slump, 4000 psi + mix design, minimal 4" thick. If parking heavy trucks on it go 6".

You don't think 3000psi is strong enough for a simple DIY garage? Not doing anything that heavy,

Dan in Pasadena · Mar 18, 2013

3000 psi is fine.

Re compact, re compact, re compact! Your floor cracked significantly because what it was sitting on was likely NOT compacted properly. If in doubt, have a local test lab come do a compaction test. 95% minimum, welded wire fabric and you're good. Still planning porcelain over a new slab?

dcs Inc · Mar 18, 2013

Go with straight bag mix. In the 70-80's 3000 was a good mix. They have so many additives in mixes these days to cut costs and still achieve it's compressive strength it becomes difficult to get a decent finish because of the limited paste to bring to the surface. I used 6 bag mix on most of my pours. That equates to a 4000 psi mix. When you order a 4000 psi mix it is 5.5 bags of cement per yard with fly ash added. Fly ash is a bye product that acts as a binder. It is harder to work with in closing the surface and shortens the finish time. Fly ash will sometimes cause coloration changes in concrete causing splotching.

MPOWERD · Mar 18, 2013

No one has mentioned whether any of these solutions are actually a good investment for you...

How long will you be living on this site? If its less than 10 years (average is 5 years) you might want to rethink the entire project. How long have you lived on the site already? How long has the floor been a problem? Is it truly unbearable or can you cope with it by making adjustments such as modifications to tool storage, etc to live with it...?

What else can you do with these funds that would give you a better return on investment instead of putting the money into the garage floor? Have to ask yourself these questions considering the shape the economy is in these days...

James-W · Mar 19, 2013

I can't speak for everywhere in the country, but here in Wisconsin a nice neat garage is a really good selling point when you want to sell your house. A lot of people who are looking for a house are especially interested in the garage, and the bigger the garage the better. It would seem that a great many people use their garage more for working than they do for parking their car. For what it is worth, I believe if he repairs the floor and turns the garage into a really spiffy space, I doubt he will lose any money should he decide to sell his house. At the very least it will make his house sell easier.

James-W · Mar 19, 2013

I was just thinking about something, and while I don't have any statistics to support this, I tend to think that money you spend on your house in order to "make it better" is money that you will get back should you decided to sell it. But let me expound on that a little.

If you do something really unusual to your house, like putting in a bowling alley, you probably won't get that money back should you sell the house. But that isn't really what most people do anyway, most people do things to make their house more attractive, or they do things to increase the square footage of their living space. For example, if you have a full basement and you want to finish it off and turn it into a really cool living space, I think you will probably get most, if not all, of your money back if you sell the house. But here is the important thing, even if you don't get all your money back, you still get the use of the space for the time you are living there and that has to be worth something.

cbracer · Mar 19, 2013

I haven't decided about the porcelain tiles yet. It would be nice but the new slab serves my main needs just fine. I've lived here almost 3 years now, and while I'm not excited about the location there isn't anything I desire which can afford to move into. So I'm likely here for a while. It's a good point though, no need to dump money into a place I'm not going to live in for very long..

The concrete guy says never to use fly ash, clean sand is so much better. He talked about the original concrete being 4.2 or something and the new stuff being 5.2 or something. The .2 number was different but I don't remember what it was. Rather than pouring onto the dirt I want to do a little layer of gravel or sand.

MPOWERD · Mar 19, 2013

James lets not take away from his thread with to much of this... Personally I spent what I wanted to so I could make my garage the way I wanted it to be because improvements are very rarely ever recouped. So I just mentioned it because no one else did.

The OP has addressed my point and hopefully he can find a solution for his floor that won't cost him to much and still give him what he wants...

Justanoldguy · Mar 19, 2013

MPOWERD said:
James lets not take away from his thread with to much of this...

I find it ODD that you raise this issue then
want it stopped when someone else voices
there opinion on it.. Weird indeed, don't you think? :eyecrazy:

ConCretin · Mar 19, 2013

cbracer said:
The concrete guy says never to use fly ash, clean sand is so much better. He talked about the original concrete being 4.2 or something and the new stuff being 5.2 or something. The .2 number was different but I don't remember what it was. Rather than pouring onto the dirt I want to do a little layer of gravel or sand.

You are getting some of your terminology mixed up. Fly ash is used to replace some of the cement in concrete. It doesn't have anything directly to do with the aggregates i.e. sand.

Some finishers don't like supplementary cementitious materials like fly ash because they tend to slow the set times somewhat but other than that they are fine.

If you decide to proceed with replacement You should definitely pay attention to the subgrade. Ideally you want a well compacted, self draining, granular material like stone or gravel. The material under the slab actually supports the weight of what you put on the slab. If the existing material is soft or expansive, your new slab will fail.

Finally I'd go with a 4,000 psi mix for a garage floor. You don't necessarily need the additional compressive strength but you'll get a more durable surface.

Good luck.

slickgt1 · Mar 19, 2013

CB, before you continue with complete slab replacement. Find a few good tile guys and price out tiles with MUD JOB. You know like my garage. You can possibly do this yourself, but if you are willing to pay $3k for new concrete, you might be able to score a deal on tile with mud job. It will address all of your issues, and give you a nice floor for the rest of your life.

Figure your budget is about $7 sq ft. I am almost sure you can find someone to lay tile and mudjob for that price.

James-W · Mar 19, 2013

I am a little confused here. From what I can see from the pictures, he has some fairly large cracks in the floor. I always thought concrete cracks for a reason and until you find and fix the problem it will continue to crack even further. Assuming that is correct, then if he doesn't fix the cause of the cracks and he tiles right over them, won't the cracks in the concrete underneath the tiles continue to get worse as time goes by? In other words, if the concrete cracks even more, won't it screw up the new tile floor as well?

pop pop · Mar 19, 2013

In my 50 year experience building projects, dcs is giving you excellent advice on the 6 bag mix. Good to see someone with experience not drinking the new kool aid additives. Only thing I'd add is do a slump check upon delivery. If more than 4", reject the concrete.

cbracer · Mar 19, 2013

slickgt1 said:
CB, before you continue with complete slab replacement. Find a few good tile guys and price out tiles with MUD JOB. You know like my garage. You can possibly do this yourself, but if you are willing to pay $3k for new concrete, you might be able to score a deal on tile with mud job. It will address all of your issues, and give you a nice floor for the rest of your life.

Figure your budget is about $7 sq ft. I am almost sure you can find someone to lay tile and mudjob for that price.

What do you mean by MUD JOB ? laying mud, dirt, sand, thinset, whatever down? The concrete cracks are getting bigger and lifting sides up, so there will be vertical movement if I leave those slabs in there. Nothing I can do that will handle vertical movement

The un-flatness is a full 1" and the slope from back to front is 2". Can't level that out

Unless you've got ideas?

Zeke · Mar 19, 2013

Racer, I say do new concrete if the floor is floating. If it was a monolithic pour, you're going to have to flush saw the perimeter. You could do a broadcast color as the new concrete is being bull floated.

pauls340 · Mar 19, 2013

I've put down thousands of square feet of Mg-Krete and I would tell you to replace that slab with new concrete and if you go with Vapor Lock 20/20 Admix in your concrete it will make that 3000 psi over 4000, for free AND you will have ZERO moisture issues in or on your concrete. Vapor Lock comes from your Mg-Krete dist. It's the best stuff in the industry and I put it on my slab 3 years ago and it works. Good luck.

cbracer · Mar 20, 2013

Zeke said:
Racer, I say do new concrete if the floor is floating. If it was a monolithic pour, you're going to have to flush saw the perimeter. You could do a broadcast color as the new concrete is being bull floated.

Not a monolithic pour, it was after the foundation and sits on just dirt.
Thanks,

jim bremner · Mar 20, 2013

Call Kina @ 562-964 6739 He poured my floor in Fullerton at 5" thick with rebar drilled into the foundation and added a handicap ramp for the wife. his crew did a pretty good job. there's a few low spots but I think that te job was worth his bill. I had some other work done at the same time and got a package price

skulldrinker · Mar 20, 2013

Fiber mesh is waste of money. Go to the barber shop and sweep up some hair,,,,same thing. I've delivered loads with 3" long wavey metal mesh in it. Now that's a lot better. Just use the real roll of wire mesh. Or sheets of heavy duty thick mesh. Don't let them add Chloride to the load that will corrode the wire mesh over time. Make sure you watch them bozo's because 90% of them just leave it lay on the stone and never lift it up so it rests in the middle of the slab. It does no good laying in contact with the gravel.

Easy just get a saw and cut around the walls and repour. I've been on hundreds maybe even thousands of garage pours over my 25 years of delivering concrete.

and for gosh sake use 4000# mix. nobody uses 3000#. Even the city of chicago fills in temporary patches for pot holes with 4000#

Justanoldguy · Mar 20, 2013

skulldrinker said:
Easy just get a saw and cut around the walls

Why? It's not necessary. :dunno:

cbracer · Mar 20, 2013

My next question: Should I have a base of compacted gravel or aggregate (crushed concrete)? The concrete guy said that aggregate is better than gravel and both are much better than sand.

It's amazing how many people want broken concrete blocks. Rather than pay dumping/recycling fees of $600, I posed on craigslist under free and got 6 calls the first day. That'll save me some money!

Herb67SS · Mar 20, 2013

Gravel vs aggragate???

Can someone help me understand the difference? Around here gravel is aggragate.

cbracer · Mar 21, 2013

Herb67SS said:
Gravel vs aggragate???
Can someone help me understand the difference? Around here gravel is aggragate.

What they call aggragate here is recycled concrete crushed into various small rocks. Gravel is all similar in size and not recycled concrete.

I give up.... time to replace my garage slab

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