# Average Cost Per Sqft

• Anyone have an average price per square foot for using Aircrete? I'm not talking about plumbing, electrical, etc, just the cost per square foot to use AC as the core building medium.

• No replies to,this post?

• There are too many variables to reply to I think. Wall thickness for instance, wall height etc. The question you ask is all about volume.

Here is something, 94lbs if cement yields a 50 gallon drum, roughly 7 cubic feet of material. A 94lb bag is say \$11. Assuming water is free and you just need foam, the foaming agent is \$45 for 160 gallons or roughly .30/gallon. I am not 100 percent sure but let’s say it takes 3 gallons water/foam for 50 gallon drum, so 3 gallons at .30 per gallon and we need 3 so we can round up and say \$1 per barrel in foam. So we are at \$12 for 7 cu feet of material.

You can figure the rest out from there. Just multiply total length of walls and total height of walls and total width of walls to get volume used and use numbers above to get cost. This doesn’t give outside coating cost.

Say a 100 sq ft room 10x10 has 40 linear feet of wall, roughly. 8’ high gives 320sq ft of wall space say 6” thick is 160 cubic feet of wall volume. I think my math is right here. So 160 cu feet divided by 7 cu ft per barrel is 23 or so unique 50 gallon barrels of aircrete. So 23 barrels of product * 12 a barrel is \$275 in cost or so.

So \$2.75 per ft not counting a roof. \$5 a ft for 1’ thick walls.

I did all this this way cause I don’t know nor want to look up the math for a volume of a sphere but you get the point. It’s cheap. :) i hope this helps.

• Volume of sphere is V=(4/3)3.1415Radius Cubed of sphere.

So, assuming a 14' dome as made at workshops, 6" or 1/2 foot thick walls, a true half sphere (dome) then calculate the volume of 14' sphere then subtract the thickness and calculate the volume again and subtract from the first. Finally, divide by 2 and this is the volume of material.

So..
Diameter = 14' feet
Thickness=.5
(4/3) x 3.1415 x 7=1.333333333 x 3.1415 x 7 x 7 x 7=1,437 cubic feet

Do again with Radius of 6.5
(4/3)x3.1415x(6.5x6.5x6.5)=1150 cubic feet

Subtract the two and dived sphere in half.
1437-1150=287/2=144 cubic feet.

Using the prices above of \$12 for 7 cubic feet or say \$1.72 per cubic foot the dome would cost \$251. This doesn't include the foundation.. So, a 14" foot dome has (pie*Radius squared) 153.9 square feet which is \$1.63 square foot in for a perfect half sphere dome that is 14 feet in diameter. Again, not counting the foundation...

I made a Google spreadsheet to calculate cost. Not sure if it's works with only viewing privilege, but your welcome to try it...

• Can someone help me calculate 120sq/ft dome please? I am having trouble understanding the calcs above...Thanks:)

• @HandyDan tHANKS FOR THE INFO!

• I have a cost an material estimator setup you are welcome to use. Just select your numbers in the green fields and it will show you the cost as well as the amount of materials to order.

Estimate Dome Cost Calculator

• A 94 pound bag of cement generally yields 45 gallons of aircrete which equals 6 cubic feet. 6 cubic feet of aircrete would make a 6'x3'x4" slab or a 6'x4'x3" slab that you could cut into blocks.

• @handydan Thanks for this very useful tool in calculating material and cost!

• @ignacio-dhome I'm glad you found it useful.

• Is there a metric calculator available? These American measuring units are very confusing.

• @Kwagga 42 KG of cement makes .17 cubic meter of AirCrete.

There is some data required to make a metric version:

What price & volume of foaming agent is used there.
Weight & price of Portland cement bags.
Dimension and cost of soft poly reinforcing fabric.

• @Ignacio-DHOME
120 Square feet done
(120/3.1428)Square Root=radius 6.18. A 12.36 foot dome

The cost for foundation and done would be \$835 ish dollars if you make it 12 foot at 4.5 inch thick walls.

44 bags of cement
3 gallons of Drexel foam agent
1 roll of soft polyester.

• @Kwagga I just use online conversion calculators. Just Google "inch to meter" or what ever units are involved.

• @Zander Thanks man! Yours seems better than mine (experienced) so I am going to use yours.

• @HandyDan said in Average Cost Per Sqft:

3 gallons of Dresses foam agent

Can you pleas describe or provide a link to this "Dresses foam agent"? I can't find it.

• @anthonydjones That was my automatic spell checker.. it's Drexel FM 160

• @HandyDan said in Average Cost Per Sqft:

3 gallons of Dresses foam agent

Can you pleas describe or provide a link to this "Dresses foam agent"? I can't find it.
There are also other almost identical foaming agents available at local farm stores.
They are used for "row marking" where the tractor squirts droplets of foam so they can mark where they went.