Vermiculite ration

[JFoster0403]

Hello, I'm trying to figure out how much vermiculite i would need to pour a
48"x48"x3" insulated core on top of the hearth stone. I'm new at this and never worked with vermiculite before. I'm just not sure how much to buy. It's not cheap! I looked into buying Ceramic Fiber Board (FB Board). but think i may go with the vermiculite. depending on the cost. Thanks for anyones help!

[david s]

That volume you need is 4 cubic feet. That is how much vermiculite you will need. Mixing 5:1 vermiculite, cement will not increase the resulting volume. When mixed you may find a slight reduction in volume ( about 10%) do not over mix or the stuff begins to break down further and reduces the volume even more. For every litre of vermiculite you need about a third ( 333mls) of water. If you overdo the water it will wash the cement to the bottom and leave the top with virtually none.
If you get the fine grade of vermiculite you will need more water, probably around 400 ml / litre of vermiculite.

[Gulf]

Originally Posted by JFoster0403

Hello, I'm trying to figure out how much vermiculite i would need to pour a
48"x48"x3" insulated core on top of the hearth stone. I'm new at this and never worked with vermiculite before. I'm just not sure how much to buy. It's not cheap! I looked into buying Ceramic Fiber Board (FB Board). but think i may go with the vermiculite. depending on the cost. Thanks for anyones help!

If you go with Vermicrete alone my advice is to pour 4" instead of 3". (4" of vermicrete is supposed to be equal to 2" of FB board). David is bulls eye accurate on 4 cubic feet for your deminsions. I think that is cutting it a little too close though. Here in the states nurseries sell bulk vermiculite in 4 cubic feet bags (course or medium). It is expensive I agree. The last bag that I bought was 22 bucks from a local nursery. If you are buying your vermiculite from Lowes, Home Depot, or Walley World you will pay considerably more buying it in the 8 quart bags. (my local Lowes price for today is $4.66 for the fine. That is expensive as all hll.

If you are trying to save money and decide to go with vermicrete search locally at a nursery for the bulk bags. I figured my vermicrete too close and since the nurseries down here close at noon on saturdays had to finnish up with the real expensive stuff. Buy 2 (4 cubic foot) bags. Any left over can be applied as insulation for the dome wether or not you decide to go with the blanket$$.

[david s]

"The last bag that I bought was 22 bucks from a local nursery. If you are buying your vermiculite from Lowes, Home Depot, or Walley World you will pay considerably more buying it in the 8 quart bags. (my local Lowes price for today is $4.66 for the fine. That is expensive as all hll."

Where I live(Australia ) the local hydroponics store or local nurseries charge $36 for a 100 litre bag so we pay more than you do. Everyone in Australia wants to be a millionaire. Electricians, plumbers and other tradies earn more than most professionals.

[Gulf]

$36 for a 100 litre bag OUCH! If the converter is right that is 113+ liters per 4 cubic feet bag.

Prices are very different from region to region here in the states. Some products are not easily found at all chain markets. I did not know what JFoster0403 meant by expensive.
I was hoping to drive home a point about locally purchased materials. I have found out since starting this venture that:
1. Local nurseries beat chain stores on bulk prices for vermiculite.
2. Local industrial supply warehouses have the same products as the West Coast (only much cheaper if you can drive to pick up)
Although, I do intend to order my peals and copious amounts of flour from the Left-Coast .

[hungng]

You tend to use a bit more than you think you'll need. I bought a 100 litre bag of Vermiculite and a 100 litre bag of Perlite and used nearly all of both bags for the same size slab as yours.

[Neil2]

Get an extra bag just in case.

If you don't need it, retailers will almost always take back returned unopened bags with no fuss.

[JFoster0403]

Thanks for the advice everyone...i decided to go with the 2" FB board. I do have another question regarding the mortar for the fire bricks. The local home depot sells "Fire Clay" but i'm not sure if that's what i need. A brick yard around here sell Heat Stop refractory mortar. Obviously, i'd think that would be better, but it's also $70 per 50lb bag. Is there anything else i can use that isn't that expensive, but equally effective?