House for my Parents

[EddieWalker]

Vapor Barrier under a concrete slab on a single story house is a misnamer. It's purpose is to control the moisture in the concrete when pouring on certain soils that will dry out the concrete when it's still wet. I have very good red clay that I will dampen before the concrete is poured and not have any need for plastic under the slab.

Radon isn't a concern on a single story slab that is on grade.

Humidity or moisture on top of a concrete slab has nothing to do with there being plastic under the slab or not. It is 100 percent the result of water content in the air and the different temperature of the concrete to the air around it. Warmer air and cooler concrete will lower the ability of the air to hold moisture, resulting in moisture on the slab. Insulation under the concrete might help this, or heating the air above the concrete to where it can hold more moisture and not creat condensation. Air movement, such as fans or proper venting will dry out the condensation before you see it in some cases, and keep it to a minimum in other cases.

And for those who want to share their belief that water will come up from the ground and go through my concrete to bring moisture into the house, I disagree. In every house there are drain lines and there are traps. Where the traps are located, the surrounding concrete doesn't touch the trap, leaving exposed dirt under your tub and shower. This soil is extremly dry and hard. I do this for a living and if I find any moisture there, it's because there was a leak.

Water will always take the path of least resistance. Going up and then through 3 1/2 inches of concrete isn't going to happen. If you don't believe me, put a 3 1/2 inch thich piece of concrete in to a puddle of water that is an inch or so deep and wait. Plan on being there a very long time, because water will NEVER work it's way up to the surface of that piec of concrete sitting in water.

And on those jobs where I have been where they do put down plastic, it's more of a joke then actually trying to keep water from getting from the ground to the concrete. I've never seen it taped, or sealed in any way. I've never seen it done in a single piece. It's cut and torn all over the place by the time it's ready to pour. It's one of those things that was done to keep the concrete moist all the way through, and nothing to do with water coming up from the ground and into a house.

Thank you,
Eddie

 

[MarkV]

Here is a pretty good article for any that would like to read more about the vapor barrier or not debate that has long been going on. www.staticworx.com/articles/moisture-vapor-barriers.php

MarkV

 

[EddieWalker]

Thank you for the link. I read it and felt it agreed with my position on using plastic to keep moisture in the soil, but then I got confused when they claimed that moisture in the soil will turn to vapor and work it's way to the surface. I don't believe that moisture in the ground turns to water vapor. In fact, I question the possibility of this even being possible. Surface water is one thing, but once you get a couple feet into the ground, temperatures drop and the soil is much cooler then on the surface.

I think that the article is misleading.

Using flooring failure as a reason for plastic under the slab does not work either. Once a new slab has dried properly, then there isn't a concern for moisture unless it's from other issues inside the house, or flooding from a poor design where surface water gets under the slab. In either case, plastic under the slab doesnt do anything anyway.

I'm not against plastic under a slab if the soil requires it. It does a lot for the strength of the concrete and allowing it to cure longer, which means stronger concrete. That is all it does, and only needed if pouring over soil, sand or gravel. On hard, red clay, it isn't needed.

Eddie

 

[jackievg]

Eddie, can you adopt me? Great house! Your parents are really lucky. Sure hope my son (7) grows up to be such a good son!

 

[ustmd]

We've had company visiting from Canada this week and haven't got a lot done. Not that it matters, I'm still talking to guys about finishing the concrete. Hopefully we can pour this week, but I don't know when, or who will do it.

Rebar is half inch, doubled up in the footings and 3/8's on a two foot grid sitting on chairs through the rest of the pad. There is 3/8's rebar sticking through the forms a foot for the porches every two feet that I will tie into when we make the forms to pour them.

Eddie
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Eddie,

I am jealous of your red clay. Down here on the Black Land Prairie (black clay), you would have dug down 3-4 ft, brought in road base, compacted it, then dug 18 x 24 perimeter beams (at least) with 12 x 18 grade beams throughout the slab.

Here is a picture of some of the foundation work for the porch we added in 2009 (engineered foundation):

 

[EddieWalker]

After finding out the guy I've used before for bigger concrete jobs was deported, and asking around the people I know for somebody they recomended, and after talking to them, I went to Angieslist.com and found the guy I hired. He was at .50 cents a foot to finish it off. He arranged with the concrete company when to be here and set the day for this morning.

He and his guys showed up about quarter to seven and started going over the rebar and setting their guide stakes. They came in two trucks, each pulling a trailer full of supplies. Three power trowels, all sorts of straight boards, rubber boots and just about everything you could think of to do concrete work.

The first truck showed up a little after seven and the last one was gone by 9:30. Almost forty yards for a total of just over $4,400 for the concrete.

They stayed and worked it until about 2pm. It looks perfect!!!!!

Eddie

 

[KENSFM]

Looks good Eddie, I always enjoy your pictures. Looks like you are off to a great start.
Take care,
Ken

 

[brin]

Eddie !!! CAUTION !! Wet Concrete....where is Oscar....Oh Geeeeez, can you imagine what Oscar will do to that...LOL

 

[EddieWalker]

In the very last picture, where it shows the cut in the concrete for the garages, you can see the electric wire to keep Oscar out. He does not like that wire!!!! LOL

Eddie

 

[EddieWalker]

I had two loads of road base delivered on Monday, but wasn't able to get to it until yesterday. Cost of rock is steadily rising and this was $22 a ton for a total of just over $1,200

I had a road in already that was wide enough to drive on, but not much else. Parking has been on dirt since I built my house. With my parents here and their friends coming over to visit, we needed more parking areas. This worked out just right!!!!

Eddie