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Hi Y'all,
I am researching underfloor insulation alternatives as perlite, vermiculite and cal sil boards are expensive as hell where i live. I have some questions and would love to see what you guys think
I am considering a 600 mm x 900 mm x 50 mm ceramic fiber board which i can shell out for but one board will not entirely cover a firebrick floor of radius 17 inches. I would rather get ceramic blanket than a 2nd ceramic fiber board and fill the gaps in the floor with it
Is it good design to make a frame out of 1.5 inch angle iron > place a 1 inch sheet of ceramic blanket on it > then place the 9 x 4.5 x 3 inch standard firebricks on it > and then glue and layer 3 inches of fiber blanket under the iron frame?
I think the iron frame being trapped between ceramic sheets might heat up too much? Idea is to use the iron frame so the firebrick can rest on it but it does not crush the blanket
OR skip the iron frame and just rest the brick directly on the ceramic blanket? i have seen some videos of people doing this in kiln builds, but those bricks are like 1.5 inches thick. The ones I plan to use are standard fire bricks 3 inches thick, i feel the weight will crush the blanket and diminish any insulative properties
Another idea along the same direction is cut a 600 mm square out of the ceramic board place it in the center of the floor and then then fill the rest of the missing sides of the floor circle loosely packed ceramic blanket. In my CAD drawing i see on the edges it is just a brick or half a brick that will rest on the blanket so it is less likely to squish.
With the remaining 600 mm x 300 mm I can cut out 50 mm cubes and surround the round brick floor with these equally spaced insulation cubes > finally rest the 4 dome sections on the insulation cubes and stuff the gaps under the dome with fiber blanket > each 1/4 dome section should be about 50 KG and the compressive strength of the ceramic board which i think is around 0.08 to 0.12 Mpa should handle it alright.
I also have easy access to Pumice, Glass wool, Magnesia block and CLC block and am thinking of skipping ceramic fiber board and ceramic fiber blanket completely, i will save a lot of money
My other alternative is to build a cartwheel type frame from angle iron and place a sheet metal cup like floor on top and fill it with clc block > topped with mag block > topped with pumice > I will do this if the insulation value will be enough to do pizza on day 1 and bread on day 2 and 3
Some questions I can't find answers to > why use 10:1 perlite mix for the floor, would it not be better to just dry fill and loose fill the perlite and then top it with fireclay and fire board? What do you guys think about magnesia block, pumice and CLC block?
I am also sharing a chart of thermal conductivity of various materials which i have culled from the internet, can someone Kindly review and correct the data, i am not sure of the accuracy of these numbers:
I am researching underfloor insulation alternatives as perlite, vermiculite and cal sil boards are expensive as hell where i live. I have some questions and would love to see what you guys think
I am considering a 600 mm x 900 mm x 50 mm ceramic fiber board which i can shell out for but one board will not entirely cover a firebrick floor of radius 17 inches. I would rather get ceramic blanket than a 2nd ceramic fiber board and fill the gaps in the floor with it
Is it good design to make a frame out of 1.5 inch angle iron > place a 1 inch sheet of ceramic blanket on it > then place the 9 x 4.5 x 3 inch standard firebricks on it > and then glue and layer 3 inches of fiber blanket under the iron frame?
I think the iron frame being trapped between ceramic sheets might heat up too much? Idea is to use the iron frame so the firebrick can rest on it but it does not crush the blanket
OR skip the iron frame and just rest the brick directly on the ceramic blanket? i have seen some videos of people doing this in kiln builds, but those bricks are like 1.5 inches thick. The ones I plan to use are standard fire bricks 3 inches thick, i feel the weight will crush the blanket and diminish any insulative properties
Another idea along the same direction is cut a 600 mm square out of the ceramic board place it in the center of the floor and then then fill the rest of the missing sides of the floor circle loosely packed ceramic blanket. In my CAD drawing i see on the edges it is just a brick or half a brick that will rest on the blanket so it is less likely to squish.
With the remaining 600 mm x 300 mm I can cut out 50 mm cubes and surround the round brick floor with these equally spaced insulation cubes > finally rest the 4 dome sections on the insulation cubes and stuff the gaps under the dome with fiber blanket > each 1/4 dome section should be about 50 KG and the compressive strength of the ceramic board which i think is around 0.08 to 0.12 Mpa should handle it alright.
I also have easy access to Pumice, Glass wool, Magnesia block and CLC block and am thinking of skipping ceramic fiber board and ceramic fiber blanket completely, i will save a lot of money
My other alternative is to build a cartwheel type frame from angle iron and place a sheet metal cup like floor on top and fill it with clc block > topped with mag block > topped with pumice > I will do this if the insulation value will be enough to do pizza on day 1 and bread on day 2 and 3
Some questions I can't find answers to > why use 10:1 perlite mix for the floor, would it not be better to just dry fill and loose fill the perlite and then top it with fireclay and fire board? What do you guys think about magnesia block, pumice and CLC block?
I am also sharing a chart of thermal conductivity of various materials which i have culled from the internet, can someone Kindly review and correct the data, i am not sure of the accuracy of these numbers:
| Material | Density kg/m3 | Thermal conductivity W/mK |
| Calcium Silicate Board | 330-900 | 0.048 |
| ceramic-fiber-board | 250/300/360 | 0.14 |
| ceramic-fiber-blanket | 64/96/128 | 0.30/0.23/0.20 |
| insulating-firebrick | 600 | 0.23 |
| Perlite | 32 | 0.051 |
| Vermiculite Brick | 485 | 0.167 |
| Vermiculite Expanded | 300 | 0.069 |
| Vermiculite Expanded | 220 | 0.071 |
| Vermiculite Insulating Powder | 270 | 0.121 |
| Exfoliated Vermiculite | NA | 0.04 |
| Concrete foam Vermiculite | NA | 0.14 |
| Pumice Specific mass | 700 | 0.23 |
| Glass wool | NA | 0.032 |
| Paper flakes | NA | 0.039 |
| Cellular Light Weight Concrete Block | 800 | 0.53 |
| Magnesia Soldering Jewelers Block | NA | from 10 to 0.181 |
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