Post frame construction questions.

[SirReal63]

Looking to do a 40 x70 x12, all living space inner framing with 2x4's & 2x6 ceiling joists. My nagging unknown is the SLAB, yes 5" thick with rebar on 24" grid, BUT are you guys going flat slab ? Or dug out beams poured in slab. EVERYTHING else I am good with. What say ye ?

Our slab is also 5-1/2" to 6" and they dug 24x24 footers as well as beams. They didn't get to 24" depth in all areas for the footer, they hit shelf rock at 12-16" in most places and drove pins to anchor the slab to the rock. We have a large amount of black clay and I wanted to ensure the slab never moved, so we went the extra mile to ensure that. A 12x12 footer is more common but it will depend on the soil you have to deal with. It varies greatly in the State so make sure and build appropriately for the area.

We went with Viega Fosta-Pex for the water lines, in the slab and as Eddie mentioned, it is insulated as well. It is common around here to do either in slab or in wall water lines, we had little worry of slab movement so we did in the slab, it was also included in the builders quote to do it that way.

If you are ever up this way, let me know, we don't mind showing you what we have done. It has been a great learning experience.

 

[Mathis bound]

Thanks Jack ! How much rebar is in your beams ? Is rhat a current picture of your build ?

 

[SirReal63]

That pic is from about a year ago, they boxed in the beams with rebar with pins driven in to prevent slab shifting. What you don't see is the thousand or so plastic chairs to hold up the rebar, they put them in right before the pour. I am framing the main house now, it is slow going when you work alone, though I do have the SIL for a few days this week. I will send you a link so you can see how far along we are.

 

[EddieWalker]

I was going to ask about the chairs, and I'm glad that you mentioned it. It's really important that the rebar is somewhere in the middle of the slab. I've heard the ideal place is in the bottom one third, but I have also read that there isn't any measurable difference between the center and the bottom third of the slab. Just as long as it's inside the slab and not sitting on the bottom like what happens with wire 100% of the time.

You also bring up a good point about footing depth. Different types of soil have different load bearing capacities. Also different amounts of movement. The black clay found just East of Dallas is rather famous for how much moves as it dries out, then when it's wet and freezes. It takes some serious footings and beams in the slab to hold it all together!!!

I'm lucky, I have red clay. It is very stable and it supports a lot of weight. Sand is probably the worse for how much weight it can support.

 

[Mathis bound]

Jack, I look foward to seeing more pictures of your build. Maybe some day take a day trip to check it out in person, the wifee is on board with my plans as long as it does not involve a mobile home, but seeing the real thing might give added peice of mind to her. Yours is 40x70 or there about right ?

 

[SirReal63]

Yes, 40x70 for main house but a portion of that will be shop space, the guest house is 24x24, both with 14' walls and a loft space.

 

[LD1]

I was going to ask about the chairs, and I'm glad that you mentioned it. It's really important that the rebar is somewhere in the middle of the slab. I've heard the ideal place is in the bottom one third, but I have also read that there isn't any measurable difference between the center and the bottom third of the slab.

I have actually read some places say that the rebar in the middle does no good at all. Being on the neutral axis of the concrete and all. Howecer it will still keep the slabs together when the control joints are cut so one slab dont end up moving higher or lower.

Ideally, as I have heard, is near the bottom or bottom 1/3. That way, with heavy load on the floor, the rebar is in tension (which is where steel excells and concrete sucks), and the top of the slab will be in compression, where concrete is excellent.