Are my concrete numbers correct?

[bmill]

 Planning a 10'x10'x7'(height) concrete room with a 8" thick walls & ceiling plus a  6" thick floor. Are my figures below correct?  :P

1 wall = 10 x 7= 70sq ft
70 sq ft @ 8" thick = 70 x .66 = 46.2 cubic feet of concrete
46.2 x 4 (number of walls) = 184.8 total cubic feet (for the walls)
184.8 / 27 (cubic feet in a yard of concrete) = 6.8 yards for the walls

Roof is 10 x 10 = 100 sq feet
100 sq ft @ 8" thick = 100 x .66 =66 cubic feet of concrete
66 / 27 (cubic feet in yard of concrete) = 2.4 yards for the ceiling

Floor is 100 sq ft @ 6" = 50 cubic feet
50 / 27 = about 2 yards

Then according to my math I would need 11.2 yards of concrete not counting any footings. It seems like a lot for this size room, have I screwed something up in my calculations?  I hate doing math in public.  ;D

[fishpharmer]

That'll be a heck of vault or storm shelter.......ifin I was a guessing man.

Sorry I couldn't help with calculations.  I have a friend I can check with next week if you don't have confirmation by then.

By the way....I was curious if you could get blue corn meal from blue corn and make some blue cornbread or blue popcorn.  You might be onto something. ;D

[bmill]

 I will post some pictures of our blue cornbread. It really is blue. We make blue muffins too.

[Radar67]

You are pretty close bmill

I got 6.92 for the walls
2.47 for the roof
1.85 for the floor

Remember to add about 10% for good measure.

12.4 yards with the 10% added.

[fishpharmer]

Thats cool.  

Would love to discuss the fine art of corn breeding with you sometime.  That kinda stuff fascinates me.  Kinda like the unknown science of fish genetics.

[bmill]

 Thanks Radar, just wanted some confirmation that I wasn't out in left field. This particular structure will be an earth bermed tornado shelter.

Fishpharmer, I just put 2 and 2 together, are those ponds off the end of Key Field? I originally thought they were crop fields. Next time I'm down there I'll bring my fishing pole and some blue corn! 8)

[Radar67]

How are you planning to seal the concrete?

If you ever land at key field, or Meridian NAS, you better let me know too. I'll make the trip to visit. ;) Or Keesler AFB for that matter.

[Don_Papenburg]

That will make a good shelter ,but how do you plan to get in it ? All the walls and floor and roof are solid  ???
I think that I would find a way to attach it to the house .  I would not want to run outside at midnight with a tornado lurking in the neigborhood when I was half asleep ,cross the yard with trees and cows fliing  through the back yard.

[fishpharmer]

Yea I see what I think are KC 135's  tankers all the time at Meridian Air National Gaurd Base just accross from the ponds.


You better holler if coming this way.

(goes for everyone ;))

[bmill]

Don, I am going to attach it to the old farm (pharm) house. You are dead on in that nobody should be running outside when the tornado hits. I intend to butt it up to the house and leave an opening for a door. I think I'll weld up my own steel door. My son and his wife live out at "the ranch" and I've got to get them a shelter as there is no basement or even a crawl space under the old house. My land is covered with oak and if a tornado ever does hit, there's going to be a lot of shrapnel in the air, that's why I'm going to use lite form and earth berm it.

Fishpharmer, I've flown right over your ponds on a few occasions and never knew it. Those are indeed kc135's that fly out of Key Field. I'm going to have to make an excuse to fly down there later this spring and stop by the phishing hole. I'll bring gifts from the Northland. Maybe you, I, and Radar can have a Forestry Forum South get together over lunch or a beer. I could bring some catfish or crappie down. 8) 8)

[Radar67]

We've been itching for a Southern Chapter meeting this spring. The last one went over very well. 

[rbhunter]

Question? If the inside measurement  is 7' wouldn't you have to allow some extra for the corners where the walls join so the walls would actually be 7' 8" long, or 6' 4" if the figure was based on the outside of the walls? Or is the amount of extra needed to small to matter?

Randy

[fishpharmer]

Nice idea about the shelter.

I am all for a meeting like that.  Would include others too, if we had enough lead time.

You leave the catfish part to us in MS.  We will let the yanks handle the crappie fish ;) :D :D

Naw just kidding, I love crappie too.  Just don't have a good supply handy.

Thats too cool you have seen the ponds.  I am always amazed at what a small world this really is.

[Chico]

You can fig 1yd of concrete will cover 80 sq ft at 4" thats how I've always done it and that will cover your 10%  I fig 11,5 yds for the pour
Chico

[Banjo picker]

The door opening will take out about 1/2 a cubic yard.  For a 3' steel door jamb. The other figures come to about 10.77 cubic yards so take out a 1/2 and you got 10.27 cubic yards.  You will have to add what ever you feel will cover the waste.  But you need to rember that you won't get all that comes in the truck a little is gona stick to the sides.  That 10 % waste probably is gona be close.   If you use that i would order 11 1/4 yards.  I have poured two such structures.  One was onto a basement the other was where you could just step out the kitchen in the carport and into the structure.  What are you going to use for reinforcement.  I would also consider putting in some sort of vent pipe in the top or side somewhere, because if the door were to be blocked or coverd with debrie  ( spelling)  you would not want to be in a concrete room with no fresh air.  Just a thought.

The difference in mine and Radars figures is I believe he figured 4  10' walls , when in reality you would only figure 2 10 foot walls and 2 walls at 8' 8" . 

If I were building me a new house, it would have such a room.  Tim

[scsmith42]

Here is the forumla that I usually use.

Lenght of wall in inches, times height of wall in inches, times depth of wall in inches will give you the total amount of cubic inches.

Take this and divide by 1728 (the number of cubic inches in a cubic foot), and you will have the cubic footage of the pour.

Do the same thing for any openings, and subtract from the wall number.

Divide the result by 27 and you get the cubic yardage needed, and add 10% for extra.


120 inches (10' width) x 84 inches (7' height) x 8" depth = 80,640 cubic inches

Divided by 1728 equals 46.66 cubic feet

Divided by 27 = 1.72 yards for the wall.

[SamB]

An old formula I've used for years with good results is; square footage x inches thickness / 300 = cubic yards to order. In your case; floor 100 sq ft x 6 in = 600, 600/300= 2yds. ; ceiling 100 sq ft x 8 in = 800, 800/300=2.6yds. ; walls 280 sq ft x 8 in = = 2240, 2240/300=7.5yds. ; 2+2.6+7.5= 12.1 allowing for an entrance and air vent subtract maybe ½ yd. I would order 12 yds. if I was doing the job. If you're feeling lucky order 11.5 yds.

[sawman]

 I've used this site before and it worked well for me on the calc.

http://www.concrete.com/calculatorsmaterials.htm#volume

[Slabs]

Yeah, ventilation.  I was gonna put a vent through one corner of the roof in mine and fix a glass cage under it with a metal grid bottom so I could put a hurricane lantern on the cage and the heat from the lantern would go up the vent and pull air out of the room with it.  Oh yeah, a louvered vent in the bottom of the door would admit fresh breathing air.

Whatever you do, plan on casting fixtures into the original pour to attach stuff to so you don't have to drill the crete and install lead or plastic anchors.  I imbedded bolts into the ceilings of my shelter and boiler room by drilling holes "not quite through the formboard" and left the threads sticking out into the rooms when the formboard was pulled off.  Some imbeded conduit and boxes into the crete for lights and switches would be a boon as long as the power was available.  Maybe a little muffin fan in another vent .  (fart fan)

[bmill]

 Slab, thanks for the suggestions. I will post photos when the ground thaws and I begin the project. I'm going over to the Liteform headquarters Thursday for their "how to do it luncheon".

Thanks to all for your inputs. Much appreciated.

[medic1289]

Your storm shelter sounds like it would make a dandy root cellar, (which is on my to do list for this summer)   sy