Just a quick easy way for us to quickly calculate a job that we are not physically looking at. Most jobs usually average 4" even if the forms are touching the ground on the exterior. If you knew how many times customers came up 1/4 yard short. Then a 1 yrd minimum delivery and a short load fee now added in because we had to deliver 2 partial loads cost about an extra $175 where an extra $30-50 from the start would've covered it more than easily. For example: 10 x 30 patio is 300sf. My calculation says (300/81= 3.7 yrds) (300/75=4yrds) or (10x30x.29167=1050/27= 3.24yrds). You might could try 3.5 yards if you are really concentrating on keeping it perfectly level, but usually 4yards would be the safe bet and waste a 1/3-1/4 yards or pour a little extra piece or something if your brain won't let you waste something you paid for. It is just too hard to use a calculation based upon perfection in the world of concrete and dirt work and definitely costly if you get it wrong.

Cool, I try to learn something new every day. Now I can relax.

Their's a 3-yard minimum here. That gets real expensive....real quick.

I've got the job lined up to be done in a week or so. Now, my wife is wonderin' if the carport slab can be 'capped' so it will "look like the driveway". GEEZ...........it never ends. :pissed:

Any thoughts?

Yeah....just bust out another thousand and cap it. When it's all finished you will be glad you did...;)

I checked on the 'net and got mixed reviews as to whether or not a 'cap' will hold up. Have you done this or know someone who did, Chip? I'm referring to pouring 2-3" over the existing slab.

i did it on a remodel around thanksgiving the finisher stubbed a few pieces of rebar to keep from the overlay from sliding then rolled on a coat of bonding agent, they call it "milk" . just lay some slate on the porch

My uncle has a house built on piers since the hurricane. He poured a slab underneath his house for parking, patio/party area but the finisher was lacking on skills and it had a 1" 1/2 dip in the middle of the slab, so everytime it rained with a strong wind it looked like a lake under his home.

He layed over his with 3" of concrete but the finisher put down some type of bonding agent before pouring and he has had no problems. This slab/cap is about 3 years old and he parks on it.

Lots of caps on patios and decks, but a driveway is a little different. If you go 3" and drill some rebar through the existing and leave it stubbed up you should be ok. But if you add 3" to your existing driveway, what are you going to do about the height of your new to match. Bring in dirt, sand, etc? Just don't make it 6" thick. That could get expensive.

Poured my driveway Friday. Turned out real good. Ended up pouring 2,050 square feet. They poured 6-7" on top of the original slab. Dude said he guarantees no problems.

Keep that 18 wheeler off of it for a few weeks......unless it is only partically loaded then maybe 2 weeks will be ok.

Did you keep it wet for the first day or so......slow cure is better in the hot sun.

Let us know in a few years......how it is holding up.