Concrete thickness explained! - The Barndominium show E136

what if I told you that 4-inch slab is stronger than 6-inch slab so I have read online multiple discussions about people trying to figure out what size or what thickness of slab they need for their foundation it usually goes something like this I'm gonna have my barndominium built and my concrete contractor suggested a 4-inch slab and somebody will chime in and say no no no that's crazy you need 6-inch slab or the other thing they may ask is like a my I'm getting a 4-inch slab for my building and it's gonna cost X amount and somebody will say well that's crazy 4-inch slab steering cost that much the problem is not all for in slabs or created equal what if I told you that 4-inch slab is stronger than 6-inch slab so we're gonna do a quick and dirty demonstration and hopefully I'll be able to prove to you that 4 inch 6 inch none of that matters without knowing a lot more details about that foundation okay so take a 4-inch slab so let's let's do this I'm gonna take this is 3/4 inch plywood 5 feet long and this is gonna be your 4-inch slab you can have a 4-inch slab on grade simply reinforce with fiber that's one number two you can have a 4-inch slab on grade reinforced with mesh wire now here's another variable mesh wire comes in six gates and 10 gauge so just because you say mesh wire I would ask you well which one the thick one or the thin one right so now we that's mesh wire now you step up from mesh wire you get into rebar so you know it's like a you know it's it's a rebar reinforced foreign slab okay what size rebar well number three or 3/8 by the way rebar is categorized in numbers number three number four number five and what that means is the the number of eighths in that rebar so if it's three eight three bars number three number four rebar is half-inch eight number eight is one-inch so so on and so forth okay well I have three it's rebar okay well what spacing right because you can have three a three bar but if you don't specify the spacing that's another that's another variable right so so well I have mine at 12 inches on Center each way or I have mine you know that's how you create your grid or I have mine at 16 inches on center so on and so forth right so now that's that's your four inch lab now it's a 6-inch slab better well it can be if they are built exactly the same however this is what I'm talking about you need to really specify or at least have your contract to specify what it is or how it is that they're building your foreign slab another thing you know the next step up of course all those that I have described so far are good for dry ways okay flat work sidewalks okay so that's that's that would be sufficient for that okay however for a foundation it is not in my opinion enough unless they say pole barn which all the load is being carried by the poles and then you pour the concrete afterwards or you know the slab then yes it I believe a four inch rebar reinforce slab may be enough however one more variable it depends on the type of soil that you have so a lot of variables so I'm hoping you're starting to understand that simply saying is six inches better than four or four inches better than six or is four inch enough there's so many more variables that you take need to take into account another variable how much slope do you have on your land okay if it's perfectly flat it's gonna take a lot less soil in preparation to bring it up to level then if you're on a four foot slope okay so all those things come to effect now are you on clay or you're on rock are you on sand as you can see tons of variables now so we have a 4-inch slab right here right is that enough for eight let's just call it a conventional home conventional barndominium no it is not enough why it doesn't have any support load-bearing beams so let's say you're gonna compare a 4-inch slab versus a six inch which one is stronger well again 4-inch slab when they say 4-inch slab that's just the surface that's what they're talking about so it's sitting like this right and then this is what you're walking on this is all you see 4-inch slab right is that enough well it depends how it's built it's six inches better it depends how it's built if you have a 6-inch slab fiber reinforced on grade versus a rebar reinforced 4-inch slab with perimeter and interior beams then the four-inch is way stronger the thickness of the surface even though it matters there's a lot more than you need to know now we're gonna do a quick demonstration and I'm gonna show you why a foreign slab can be a lot stronger than a six inch or even an eight inch depending on how it's built so we set up a quick demonstration right here so right now this is a 4-inch slab on grade okay and I'm gonna walk the plank all right we're gonna see what this thing's can do now I'm gonna get a tape measure by the way we are bringing this video to you from Daniel's cabinet shop ah I almost walked across this alright so this thing is you know show it six inches off the ground okay so I'm gonna walk this and we're gonna see how much deflection we get so I'm gonna come in about a foot in look how much deflection we have already and I'm not even putting my full weight on it now you can see where this is going okay I'm right in the middle there went or falling slab cracked so we got it held up pretty good there for a while we're getting about a good four inches of deflection before it broke that's a 4-inch slab okay now this is also a 4-inch slab same 3/4 inch plywood same width same length except now we have support beams this is exactly the same principle that you have the reason you have support beams on your slab okay so again this is a 4-inch slab and we're going to test it so this one is nine and a half ten inches off the ground okay and we're going to measure deflection okay there I am I can't read the tape what's a deflection right there Danny so pretty much no deflection whatsoever again this is the exact same thickness plywood they were actually both cut from the same sheet the only difference is one has support beams the other one doesn't so I hope this small demonstration is enough to show you that foreign slabs are not bad okay they are actually the most widely used thickness of slab in residential construction however it matters a lot how you build it okay again this was just quick and easy demonstration but I hope it shines enough light in the point that I've been trying to make in all those Facebook groups and such where I tell people it's not enough information for each lab saying that you have a 4-inch slab it is not enough information to guys can build them totally different one guy can be quoting this boring slab and another guy can be quoting this 4-inch slab okay so you need a lot more information that simply the thickness of the slab okay well I hope that helps you make a decision and I hope that shared some education on concrete slabs okay now you can get into 3000 psi 3500 psi we'll get into that in another video but I'll tell you that right now you do not want anything less than 3000 psi however for you to not have to worry about any of this that way you can sleep at night and know that you're getting the correct foundation for your home get some soil testing done and have your slab engineered that is going to eliminate any potential miscommunication or comparing apples to oranges whenever you're comparing two different contractors if you have a set of plans engineered for your foundation you can send the same plans to two different contractors and say how much for my slab they will bid exactly what's on the prints I hope that helps and we'll see you next time we are Texas bar no mediums [Music]

Channel: Texas Barndominiums

Views: 156,541

Rating: 4.6207056 out of 5

Keywords: Texas Barndominiums, Texas Barndos, Tx Barndominiums, Tx Barndos, Erik Cortina, How To, DIY, Custom Metal Homes, Metal Buildings, Texas, Barndominiums, Barndos, Metal Building Homes, concrete, slab, knowledge, test, proof, plans, blueprints, education

Id: -PiVezRzGLE

Length: 10min 18sec (618 seconds)

Published: Fri Jun 21 2019