Mostly DIY Backyard Garage Build

In reply to Antihero :

Yeah, but he's gonna lose a lot of money if he tries to insist it be ripped out without cause.

He needs engineering. 
 

If he tells them to rip it out, they WILL walk. They've got 50% of the money for the job. That easily covers the cost of the footings.

I am strongly doubting it will need to be ripped out. 
 

I do agree with getting engineering that includes this footing as an existing condition. 

SV reX said:

In reply to Antihero :

Yeah, but he's gonna lose a lot of money if he tries to insist it be ripped out without cause.

He needs engineering. 
 

If he tells them to rip it out, they WILL walk. They've got 50% of the money for the job. That easily covers the cost of the footings.

You are not wrong, although I missed the 50 percent down part, I personally do thirds usually.

Engineering has to happen for any of the next steps, whichever way is needed 

In reply to Antihero :

It's 50. Travis and I have been speaking directly. 

SV reX said:

I am strongly doubting it will need to be ripped out. 
 

I do agree with getting engineering that includes this footing as an existing condition. 

I think they could engineer something where it's basically a mono pour on top of " hardened subbase" rather than calling it a foundation. It'll probably need the elevation raised to cover whatever they need to do there instead of demo.

SV reX said:

In reply to Antihero :

It's 50. Travis and I have been speaking directly. 

Ah, ok .

Here's a random idea I had while trying to remove a very rusted on wheel:

Bury the concrete in a few inches of  dirt and cut off the rebar they stuck in. The idea is that the slab is a totally different entity than the GigantoFooting.

Trench along the edge of the GigantoFooting down say......18 inches about 6-8 inches wide all along the outside edge. Bend continuous rebar from the slab all the way down the trench leaving a little gap so it doesn't catch the ground. You will also either want to have plastic on the side of GigantoFooting or dirt to bond break it from GigantoFooting.

This means that you can use the j bolts you need to, it'll hopefully be low enough that you won't have water intrusion and GigantoFooting isnt connected to your slab at all 

Down side is it's gonna make your structure bigger by 12-16 inches minimum and it'll cost a little more to build alon. Because you had to get a variance it might mean you have to get it signed off again.

It's literally a 10 second idea while cursing at my car so It needs some more follow thru but there's an idea

What's the vertical line elevation delta from top of new jumbo footing to the existing garage floor slab?

I am wondering if you can still place a 12" tall thickened slab edge on top of the footing. With our "almost nothing" frost line... it might work just fine to anchor the walls into a 12" thickened edge. 

In reply to OHSCrifle :

A 6" garage slab would be resting directly on top of the jumbo footing. The stem walls would also start from that same height.

 Travis, eventually, you will inhabit the ultimate version of the suburban car guy domain.  Condolences on the crap that happens when you try to pay people to do their jobs.

At my last house in CA, I tried three times to pay idiots to build me a (kind of long and steep) driveway.  It never happened, then I sold the house.  It's amazing how some people get paid for sucking at what they do . . .

I've got a terrible story about working in construction in my teens and having to move an entire perimeter foundation trench (custom house) three feet up a hill (after we completed the rebar and forms in the wrong spot) . . .

I look forward to seeing the future product!

maschinenbau said:

In reply to OHSCrifle :

A 6" garage slab would be resting directly on top of the jumbo footing. The stem walls would also start from that same height.

I was inquiring about the existing garage floor. Is the new building's floor slab going to align (be level) with the existing garage that's nearby?

In reply to OHSCrifle :

Yes, the new garage will be level with the attached garage's floor. To do that from this footing, the slab will be just over 6" thick.

In reply to maschinenbau :

I'm interested in knowing... Why does that matter?

In reply to SV reX :

So I can roll inop cars in and out of both garages or between them :) This is GRM isn't it??

I spent all evening reading about concrete and building codes. The more code I read the more I'm okay with this situation. My county simply follows IRC 2018 (with some amendments to delete a lot of environmental stuff LOL), which in Ch. 4 Foundations requires plain (unreinforced) concrete footings to have a thickness greater than "projection", which is the difference in width between the stem and footing. For my heckin' 20" to 24”  wide footing (which only needed to be 12" wide per code), assumed to be plain (not reinforced even thought it partially is), with a 6" wide stem wall, the projection is 9" on each side. The thickness is much greater than 9" at a whopping 24 to 30" or so, and the code has no maximums for concrete thickness. I've also read that a good "rule of thumb" for unreinforced footings is to go thicker than it is wide, and that's exactly what I have. Basically, reinforcement is not required, it's just extremely common because it is way more efficient to build that way, but perfectly acceptable if you go thick enough. IRC also allows a slab resting on edge of the footing, which they call a basement foundation. This garage is essentially a walk-out basement due to the grade they cut into, and has a foundation to match that. Plenty of houses have basement garages and they are often built this way. I can also have up to a 48" tall 6" wide poured wall before it needs to go thicker, and the back left corner is just under that. I have another friend in Georgia who recently built his garage this way: cut into slope, basement foundation trench footing, CMU walls, and slab directly on footing, and it's fine and passed inspections. Maybe it's not how they do it up north (or usually here) but I really think it's going to be okay, as long as the gravel and compaction is good. Engineering approved; I'm moving on with my life.

We talked about it, they admit their mistake and they regret not just doing stem walls all the way around. It would have cost them like half, maybe even less, which of course they ate. Trying to do a turndown on two sides lead to confusion with their team during the pour. It was a dumb call on their part from the beginning and I didn't know enough yet to correct them. But we're moving past it. They're forming stem walls now and drilling the non-wall portion for epoxied threaded rod.

In reply to maschinenbau :

So....a lot of this isn't exactly right but I'm gonna bow out on this because I feel like you are predisposed to wanting it to be ok and that's fine because in the end it is your money and your shop.

I wish you the best of luck but I'll leave you with this:

You need an independent engineer to sign off on it. It kinda sounds like you looked into it personally, if so you need someone not connected to the project to look at it.

The things I'm telling you are not based on research, other people's experience or reading up on it. It's based on watching other people's vast amounts of money, sometimes life savings get eaten up by situations like this. I've fixed things similar to this, not exactly obviously but in the ballpark. You won't find this situation in a text book/website/etc because no one does anything like it that has done concrete more than once and after doing it, won't do it again.

Use a lot of steel in that slab. Like.....#4 less than 2ft on center or #5 2 ft on center. You have a 6" thick slab so #5 is perfectly fine.

When they cut in expansion joints be aggressive, and make sure it's a full quarter of the thickness of the slab.

Good luck

In reply to Antihero :

That's massive overkill. We simply don't need to do that in this region. 
 

I respect your knowledge of concrete and you've made some good points, but some of what you are saying is absolutey not necessary in this situation. 

SV reX said:

In reply to Antihero :

That's massive overkill. We simply don't need to do that in this region. 
 

I respect your knowledge of concrete and you've made some good points, but some of what you are saying is absolutey not necessary in this situation. 

Yes it is, that's the point.

And seriously, you can't say one of those statements with the other and that's kind of the problem here.

In reply to Antihero :

Why not?  There is nothing contradictory in those statements. 
 

Your recommendations are bordering on fear mongering.  They are excessive, not in keeping with the code or regional good  practices, and likely completely unnecessary.

I like your idea of getting a simple engineering footing design, but that's as far as I'll go.  
 

You are experienced and knowledgeable. I am too.  Over 40 years.   I have never seen a failure in this region like you are describing, and I have never seen the methods you are describing. 
 

The footing is an odd design, but it is seriously overbuilt for the loads and stresses it will be subjected to.

In reply to SV reX :

Have you seen a foundation built like this? 

It's not fear mongering, and that's below you for mentioning it.

Seriously, I understand it's easier to go with it and unfortunately I've been on these kinds of jobs and bids dozens of times. I get it, you don't see it yet but realize that none of what I'm explaining is really overkill with the full scope of the project.

Nor do i expect most people to have experience in these kinds of things, this is way outside of almost anyones expertise, it's outside of mine by a little because it's very stupidly done.

But, I am a concrete guy. I've done all sorts of weird stuff, I've fixed all sorts of weird stuff and boy howdy do I recognize that this is fact weird stuff.

I really don't know why I'm in this thread , I learned years ago to let these sorts of lost causes go, but I tried to help.

In reply to Antihero :

Really?

Antihero said:

"...I guarantee the slab cracks if it's connected to a heavy sinking object. Huge gaping cracks without heavy steel in the slab."

I respectfully disagree. 

In reply to maschinenbau :

Looking forward to your progress! 😊

Following, I just was in this forum after an update to one of my projects and saw this. I've been dreaming of a shop for a couple years myself since I moved from a house I had a 20x20 detached garage.

Just today I measured part of the building I work at, since I walked around and saw a garage area. The owner of the business stores a car here sometimes when he comes up from Florida. Guess the size? 22x26. I spent part of my work day planning out how I could use that space. So seeing your thread I'm interested to see how it comes together for you. 

Here's what an odd 22x26 looks like with a step up to the rest of the building. 
 

SV reX said:

In reply to Antihero :

Really?

Antihero said:

"...I guarantee the slab cracks if it's connected to a heavy sinking object. Huge gaping cracks without heavy steel in the slab."

I respectfully disagree. 

And you would be totally wrong.

This is the hill you want to die on? You think that having a brittle cracker up against a compacted not moving subbase, but with a sinking 40,000 pound weight connected to all sides won't crack????

Do you think it's gonna bounce or flex or something??!?

With overkill steel and enough relief it may not crack outside the expansion joints, but even then it's cracking. All concrete cracks, you just gotta control it.

Seriously wtf Twilight Zone episode have I tuned in to?

Also seriously, let it the berkeley go.

This isn't our thread, it isn't our money and it isn't our problem.

We need to stop putting in his thread