[jad]

Would like to cover the dirt area under the screen porch (about 16 X 16) so it will be better/cleaner for storage.
I live in North Carolina and we don't get any real deep freeze's so I don't think I would need to go real thick with the concrete, but how do I
determine the thickness.?? I am thinking 1 or 2 inches might be enough, but I don't want it to break up in a few years. Do I need to put a base of gravel if so how thick?
Also thought about trying to use some cheap pavers but I thought the concrete might be a little easier....

 

[Aggie67]

If it were my slab, it would be 4 inches thick, with a 4 inch gravel base over compacted or undisturbed earth, vapor barrier, and wire mesh reinforcement. I'd also look at drainage in the area of the slab, because I wouldn't want the soil to wash out underneath it or the slab to sink. Best bet it is talk to your town's building department when you go for the permit, and make sure there aren't any local requirements.

Correction. I re-read the post. I thought this was a patio, not a crawl space.

 

[Jim Hart]

I think you're going to need at least 2" to 4" of compacted crushed rock under 3" to 4" of concrete. The concrete will need steel rebar or wire mesh so it doesn't break apart and you don't want that too close to the concete surface.

 

[jcalvin]

I may just be lucky but I bought a couple yards extra concrete for my barn driveway when I poured some footers closeby. The truck backed up and I just raked it out somwhat level and started rubbing it down. I have driven the tractor with the forks loaded to the max at around 1200lbs. Concrete hasn't cracked yet and been down for about 10 years. It is a whopping 1-1.5 inches thick. Wouldn't recommend repeating that hoping for the same results though.

 

[COLDIRON]

Two inches

1 or 2 inches might be enough... i donno exactly .. lets wait for other answers

It's just going under a screen room for storage no support 2" should be good.

Don't kill yourself or overkill, if it was structural I would have a different answer.

Sme guys would have you doing a footing and slab to hold up a skscraper.

 

[Scuba_Dave]

How much room do you have under the screened porch?
Just a crawl space?

I've picked up free patio block from people
If its just a crawl space area that's all you need
If a car can drive under there then you should put in more

Any tree roots that may push up the concrete?

 

[jad]

OK.... looks like 2" might do it. That's what I been thinking all along.
about half the space you can stand up in ( about 6 feet ) but the other is about goes down to about 4 feet, because of the slope of the land.
All I want to use the space for is storage of mostly yard stuff...

 

[philS]

What's the access to the area? Is it in front yard, back yard, up a slope? Even at 2" thick you're talking a couple of yards of concrete, which is that annoying amount in between what's easy to do by hand and what's worth mounting a full-scale invasion force - ie. transit-mix, line pumper, and several friends.

If you're going to rent a mixer and wheel barrow in everything, I'd go with a 2" slab. No gravel, but make sure you're down to clean dirt everywhere - rocks, sand, are fine but no trash, wood, etc. I would however put down a layer of steel mesh halfway in the slab. It's cheap, little work, and may prevent some hassles later. I'm assuming you've done concrete work before but if you've never done flat work, get a little "how to" book or just Google. You don't need to float it carefully but you will need to know how to screed and rough float it, etc.

If you're like me and lazy, I'd have the mud delivered and hire a line pumper (maybe $250?). In which case, might as well do a 3" slab as it won't hardly cost anymore or be any more work.

Some places you can find a small-lot concrete source, perfect for a pour of only a couple of yards. You can also sign up for what we call a "hot load" - some truck that ends up with a few yards left over will come by your place on their way home. But you'll get very little warning so you can't arrange for a pumper (or friends!).

HTH

 

[My Old House]

4" concrete with 6x6 WWF over 4" compacted gravel base.

 

[wildcat]

It's just going under a screen room for storage no support 2" should be good.

Don't kill yourself or overkill, if it was structural I would have a different answer.

Sme guys would have you doing a footing and slab to hold up a skscraper.

I doubt they will approve a permit for 2" S.O.G. Not getting a permit will create the potential for all kinds of problems if they ever sell the home, or the local building official gets wind of unapproved work.