# easy way to find out thickness of basement floor (conrete)?



## anuvanoob

*easy way to find out thickness of basement floor (concrete)?*

I had to drill a hole in my basement floor (concrete) for a project. I was shocked when I drilled through the concrete so quickly. What's a quick and easy way to determine the actual thickness of the concrete slab?


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## TarheelTerp

anuvanoob said:


> I was shocked when I drilled through the concrete so quickly.
> What's a quick and easy way to determine the actual thickness of the concrete slab?


thickness will vary


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## Canarywood1

anuvanoob said:


> I had to drill a hole in my basement floor (concrete) for a project. I was shocked when I drilled through the concrete so quickly. What's a quick and easy way to determine the actual thickness of the concrete slab?


 


There's no quick,easy,or cheap way to do that,only way i know of is to core it,but basement floors can be 3-5 inches.


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## Bondo

anuvanoob said:


> *I had to drill a hole in my basement floor (concrete) for a project. I was shocked when I drilled through the concrete so quickly.* What's a quick and easy way to determine the actual thickness of the concrete slab?


Ayuh,.... Ya just Did it,... 

Measure the drill bit, 'n note the depth it pushed through...


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## anuvanoob

The quick & easy way I determined the actual thickness was by bending the end of a paper clip into a small hook, sticking it through the drilled hole, fishing for the bottom of the slab, marking where the paper clip meets the top of the slab, removing the clip and then measuring from the bottom of the mark to the top of the hook's end. Its 3/4". Yes, that's three quarters of one inch. That worries me. Anyhoo, that method worked great!


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## Bondo

anuvanoob said:


> The quick & easy way I determined the actual thickness was by bending the end of a paper clip into a small hook, sticking it through the drilled hole, fishing for the bottom of the slab, marking where the paper clip meets the top of the slab, removing the clip and then measuring from the bottom of the mark to the top of the hook's end.* Its 3/4". Yes, that's three quarters of one inch. That worries me*. Anyhoo, that method worked great!


Ayuh,.... 3/4" keeps yer feet dry, 'n outa the mud....

It ain't like yer drivin' a Truck around on it...


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## tony.g

anuvanoob said:


> I had to drill a hole in my basement floor (concrete) for a project.


What actually is your project? If you are planning to install a drop forge, or a 100-ton sheet-metal gullotine, you might find 3/4" won't do. If you are just fixing some angle brackets for a workbench, you should be OK.


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## Canarywood1

anuvanoob said:


> The quick & easy way I determined the actual thickness was by bending the end of a paper clip into a small hook, sticking it through the drilled hole, fishing for the bottom of the slab, marking where the paper clip meets the top of the slab, removing the clip and then measuring from the bottom of the mark to the top of the hook's end. Its 3/4". Yes, that's three quarters of one inch. That worries me. Anyhoo, that method worked great!


 


Did you only drill one hole, and how old is the building?


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## wkearney99

And is this clearly part of the whole slab, or possibly an area that was patched at some point in the past?


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## anuvanoob

Really?! 3/4" is okay? I was under the impression that a concrete basement floor should be at least 2".

Anyhoo, I don't know the history of the basement construction, just bought the house late last year. I do know the house was built in 1918.

The project I'm working on is building a frame for an accent wall (non load bearing). I'm fastening the bottom plate to the concrete floor using concrete screws (2 3/4" Tapcon).


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## wkearney99

A good place to start would be the permitting office to see what's been filed for work done to the place. Always helps to know what was handled with a permit, because it can also give you insight about what wasn't done with a proper permit. With or without is no guarantee either way. But it'd give you some insight beyond just what you see in front of you. The same thing can be done when the next owner looks up your permit for the job.

What's considered OK today wasn't always that way. Maybe it didn't have a floor at all, or had one removed at some point, either way somebody at the time thought it was OK to put down what you've discovered now. But since you've found something rather thin you might want to take a hard look around at the rest of the structure. Check that other walls and load bearing points appear to be sufficient. Better to know that everything else is in decent shape before you spend money on something new, right?


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## Canarywood1

anuvanoob said:


> Really?! 3/4" is okay? I was under the impression that a concrete basement floor should be at least 2".
> 
> Anyhoo, I don't know the history of the basement construction, just bought the house late last year. I do know the house was built in 1918.
> 
> The project I'm working on is building a frame for an accent wall (non load bearing). I'm fastening the bottom plate to the concrete floor using concrete screws (2 3/4" Tapcon).


 


Basement floors are supposed to be 3- 4 inches thick,but as previous poster said it probably started out being dirt,and someone "upgraded" to 3/4 inch.


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## gregzoll

wkearney99 said:


> A good place to start would be the permitting office to see what's been filed for work done to the place. Always helps to know what was handled with a permit, because it can also give you insight about what wasn't done with a proper permit. With or without is no guarantee either way. But it'd give you some insight beyond just what you see in front of you. The same thing can be done when the next owner looks up your permit for the job.


Doubt they are going to find any permits from 1918. Lucky if there are records that go back that far, since most county offices if they did not get a chance to move the information to microfilm or microfiche, or still have the books they kept records in, that are still legible, it would be a Wild goose chase that would be pointless.

Also, most counties only retain records for so many years, and when they destroy those records at that time, they just make a notation and that they were "archived" or warehoused. You would be surprised how quickly stuff disappears once it gets "warehoused" and never to be found again.


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## anuvanoob

Well, there was plain ol' dirt on the paper clip from poking around down the hole. This hole I drilled is less than an inch away from the foundation. Does that change anything (i.e., maybe slabs are usually thinner near the foundation)?

Also, down the road we plan on digging up the basement floor so we can lower it a couple of inches (I keep bumping my head on the beams and ducts). If the slab is indeed 3/4" throughout then what does that mean for our plans of lowering the basement floor? Please tell me its still possible. Please?


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## gregzoll

Doubtful that you can lower it any. The footing would be right around the 3/4 mark, if you drilled just near the wall base. You just have to live with it, otherwise you will be in for a surprise in how much it costs to raise a house for more head room in a basement area.


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## wkearney99

Lowering the floor is not a trivial exercise. What has to happen is the foundation has to either be replaced entirely (propping up the house and putting a new one under it) or by underpinning it a section at a time. Either way, this is not an inexpensive endeavor. And it most definitely is not a total DIY job. There's a lot of engineering that has to go into it. Soil conditions, weight loads, local codes (earthquakes, etc), drainage, radon, and more. 

Permits exist for a fair amount of time. It never hurts to actually check. Don't just assume you won't find anything useful. Sure, you're not likely to find everything back to 1918, but that's no reason not to at least inquire. Unless you want a printed copy many permitting offices will let you review a list of what they know about at no cost.


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