Concrete thickness explained! - The Barndominium show E136

Erik explains in detail the difference between 4" and 6" concrete slabs and how 4" can be drastically stronger than 6" if built properly.

#TexasBarndominiums
#Barndominium
#Concrete

Gear I use to shoot videos:

[tollav]

My wife and I have this argument all the

[johnbalgavy]

"Have your slab engineered" -- the most valuable part of this video. Following local building codes will generally keep you out of trouble. Knowing the subgrade soil characteristics is crucial -- they may lead you to build over code. If you're using reinforcing in a slab, always support on some kind of chair or concrete brick (with compressive strength greater than your concrete.)

[Zxt]

Extremely well rounded analysis. Anything complex has to many variables to explain in a quick youtube video but you hit the nail on the head.

[montanaplease]

I tried telling my wife that 4” is better than 6” but she just won’t listen

[tylertyler]

I just did a chicken coop/small barn 12x12. Did a 6 inch slab with fiber reinforcement. 3500 psi concrete. I couldn’t afford rebar, but my neighbor had cattle panels he was looking to get rid of. Not sure of gauge size but they’re roughly pencil thickness. I cut them to size and threw them in the hole, they sit a couple inches up from the bottom of the slab. It’s bulletproof for what it is

[franciscozahradnik]

As an architect I studied 5 years and another 2 to get the degree. Now there are tables that consider the resistance of the concrete, steel reinforcement you use and gives the load it can support. Also the sub base of gravel and sand over compacted soil. In any case slabs are not considered as supporting the framework of the building, you need foundations. For an house, 3" is enough with an reinforcement mesh and a good leveled compacted sub base. It is not a floating slab on a high rise bi¡building.

[Chickmamapalletfarm]

Great information. We are considering building a slab for a swim spa/ hot tub on
ground that has had an above ground pool weight on it for many years. This information is exactly what I was looking for. Thanks 🙏

[ganzeytyler]

I thought my dad was crazy going with high psi, fiber, wire mesh, AND rebar for his driveway. We spent a month prepping, easily 100+ hours walking a compactor. But 15 years later not a single crack, And it does rise a good inch or 2 during a cold winter. dont remember exact size but it was ~35yds of concrete @ 4"

[jesusfreakster]

I’m planning for residential hobby shop and low and behold it’s Erik Love your [now] channels .

[ShopperPlug]

It's important about soil type, following code due to location, how big the slab is and how much load its going to withstand. Some cities requires you to dig down at least 4 feet down regardless due to following frost line code.

[lilbullet]

I remember my late fathers company (god rest his soul), laying some HUGE reinforced Heavy load bearing Monolithic floors at a Rolls Royce engineering factory 12 inch deep. 8 inch of concrete with a 4 inch Granite topping laid on top before the concrete fully sets They were more like a 'Work of Art' than just a floor.

[kevin]

I love it when you get under cut in job then when it all goes wrong the home owner contacts you asking if you can fit! lol

[kubota]

Great video
So many variables. Same goes with compaction of underneath soil and preparation.

[thehappytexan]

Good info! Matt over on the build show has some really good videos showing the process from A to Z on how/why support beams or even columns are a must.

[garybiggs]

I'm going to go with a 10" slab for my garden shed with fiber and mesh sandwiched by two grids of #6 rebar just to be safe!

[davidmizak]

It's fascinating material you offer to your audience. Thank you very much for contributing. A heartfelt thanks!

[pipelinerskilllabro]

So i need to pour a 12 inch slab under my 4 inch slab ?

[johntucker]

The basic structural analysis is that a horizontal support element incurs bending forces, which are really compound of compression at the top of the element and tension at the bottom. And material-wise, concrete is exceptionally strong in compression but its worthless in tension it pulls apart like dirt.... in contrast, steel cable is exceptionally strong in tension but worthless in compression, sorta like string. So how it works is, if you embed some grade of steel near the bottom of the slap, some grade of steel with good tensile strength, then you make the entire slap vastly stronger than if you just poured concrete all by itself.

[roberthigbee]

Concrete thickness explained? No, not if you are actually trying to design a slab. Yes, if you knew zero about slabs going in and just wanted a few moments of entertainment and also wanted to know a tiny bit more. The Demo at the end was only superficially applicable to slabs. He cheated by making a “T” cross-section since the slab stiffening concepts he mentioned were about putting rigid elements inside the slab and not about selectively hugely extending the slab depth which is what the reinforcing rib on an”T” section does. A better demo would have been to glue a wire grid mesh to the underside side of the 3/4” plywood to crudely simulate the effect of adding rebar. He also failed to mention that there are various strength grades of concrete (e.g., 3, 000 psi) as well as special recipes for what percentages of grout, stone aggregate, sand, water, etc. to include in the mix. He also did not mention about the effect of the vertical position of the metal reinforcement, for example, if it is laid perfectly flat on the ground when you pour the slab, the metal will not be sufficiently imbedded and will pop off the bottom surface of the concrete when a moderate load is applied. He also explained nothing about how to design the underlying gravel bed, why you might want to add drainage pipes in the gravel, or add insulation (e.g., 2” 30 psi compressive strength closed-cell XPS) and also the use of adding a vapor barrier (e.g., 15 mills thick) on top of the insulation that should go under and around the slab’s perimeter.

[richardford]

Good stuff. Getting ready to build
A retirement Barndo on 12 acres
in Southeast Texas. We want it
done right.