Thermal Break Options for pouring concrete landing up to cooking floor

[n8huntsman]

I need some ideas of how I can create thermal break. I'm going to pour my entry and landing as part or my countertop and build the entry arch on the concrete. So I'll have to have some sort of a thermal break. What are the options for this? Can I just pour a ribbon of vermiculite-concrete between the cooking floor and the entry?

[n8huntsman]

Re: Thermal Break Options for pouring concrete landing up to cooking floor

Text got cut off above.
I need some ideas of how I can create thermal break. I'm going to pour my entry and landing as part or my countertop and build the entry arch on the concrete. So I'll have to have some sort of a thermal break. What are the options for this? Can I just pour a ribbon of vermiculite-concrete between the cooking floor and the entry?

[n8huntsman]

Re: Thermal Break Options for pouring concrete landing up to cooking floor

Very cool image. Your entry floor looks like it's built on the insulating board. My entry floor is going to be part of the hearth, with no insulation. Looking at the hearth from the side, it will have a step up to the entry floor so that it will be level with the cooking surface.

[Lburou]

Re: Thermal Break Options for pouring concrete landing up to cooking floor

huskerduck, enjoyed your picture, thanks!

huntsman, look in my signature for pics of thermal breaks. One of my breaks would work in your situation I think. HTH

[n8huntsman]

Re: Thermal Break Options for pouring concrete landing up to cooking floor

Heres a cross section of my plan:

[david s]

Re: Thermal Break Options for pouring concrete landing up to cooking floor

Huntsman,
I use vermicrete for my thermal break, although mine is between the outer decorative arch and the entry. If you are designing it further in (as in your drawing) I think you will see higher temperatures so it might be better to use calcium aluminate cement and vermiculite for your mix there. The thermal break apart from reducing heat loss, will also act as an expansion joint if made of a somewhat flexible material, like vermicrete. This will prevent the cracking of the outer decorative arch.

[n8huntsman]

Re: Thermal Break Options for pouring concrete landing up to cooking floor

Aside from the lack of a thermal expansion joint, what would be the downside of laying a row of IFB between the floor and the landing?

Does IFB hold up to wear and tear? I see some people cover it in Stainless when used as a thermal break but I didn't know if they did this for aesthetics or to prevent wear. Seems counterproductive from a thermal standpoint so I'd like to avoid using metal if the IFB will hold up on its own.

[david s]

Re: Thermal Break Options for pouring concrete landing up to cooking floor

Aside from the lack of a thermal expansion joint, what would be the downside of laying a row of IFB between the floor and the landing?

Does IFB hold up to wear and tear? I see some people cover it in Stainless when used as a thermal break but I didn't know if they did this for aesthetics or to prevent wear. Seems counterproductive from a thermal standpoint so I'd like to avoid using metal if the IFB will hold up on its own.

IFB's are pretty soft, you can scratch them away with your fingernail and it is in an area that gets a lot of wear. That's why I use vermicrete because you can adjust its strength. With some vigorous pointing you can get the top surface smooth and relatively strong while deeper down it remains somewhat flexible. Unfortunately you can't have strength, flexibility and insulating all in one too easily. Covering over with stainless is a good solution, but use thin stuff (0.55 mm) A square tube will not allow expansion and if it's thick (because of conductivity) will not work well as a thermal break.

[n8huntsman]

Re: Thermal Break Options for pouring concrete landing up to cooking floor

So if I use calcium aluminate cement and vermiculite, it will hold up and still provide an expansion joint?

Anyone have an idea of what kind of k-value I could expect from such a mix?

If I did go the IFB route, would it be that difficult to remove the IFB's and drop in new ones every once in a while?

Of course this would only be the ones on the landing and not the ones between the dome and the arch. Those I imagine would be fine since they wont get the abuse?

[n8huntsman]

Re: Thermal Break Options for pouring concrete landing up to cooking floor

I posted this in my build thread but did not get a reply. I apologize for double posting but since it relates to the thermal break, it probably should have been here to start.

I need to figure out the vent and chimney area before I start really laying some bricks.
I have .012" (.3mm) Inconel sheet available to me which would be, in my opinion, acceptable thermal transfer even though I was originally against metal. I think it's thin enough that it should be okay to cover an IFB or some calcium silicate. I also have access to the equipment required to make the design shown. The three options are:

Option 1: Use a 4.5" wide IFB (which is what is shown) and make an Inconel channel to go all around the top and bottom or the arch to protect the IFB.

Option 2: Use a smaller width, 2" maybe, of calcium silicate (similar to what is shown except thinner) and make the same Inconel channel to go all around the top and bottom to protect the calcium silicate.

Option 3: Place a 3.5" layer of aluminate cement and vermiculite to go all around the calcium silicate replacing the Inconel.

The Inconel is virtually free so don't consider cost. What would you go with?

[deejayoh]

Re: Thermal Break Options for pouring concrete landing up to cooking floor

I used a piece of Square stainless tubing. Wears great, looks good, and doesn't transfer much heat at all because the steel is quite thin. Others have done the same with good results.

[david s]

Re: Thermal Break Options for pouring concrete landing up to cooking floor

I posted this in my build thread but did not get a reply. I apologize for double posting but since it relates to the thermal break, it probably should have been here to start.

I need to figure out the vent and chimney area before I start really laying some bricks.
I have .012" (.3mm) Inconel sheet available to me which would be, in my opinion, acceptable thermal transfer even though I was originally against metal. I think it's thin enough that it should be okay to cover an IFB or some calcium silicate. I also have access to the equipment required to make the design shown. The three options are:

Option 1: Use a 4.5" wide IFB (which is what is shown) and make an Inconel channel to go all around the top and bottom or the arch to protect the IFB.

Option 2: Use a smaller width, 2" maybe, of calcium silicate (similar to what is shown except thinner) and make the same Inconel channel to go all around the top and bottom to protect the calcium silicate.

Option 3: Place a 3.5" layer of aluminate cement and vermiculite to go all around the calcium silicate replacing the Inconel.

The Inconel is virtually free so don't consider cost. What would you go with?

A stainless steel section fabricated as shown in your drawing should be a good solution, although thin stainless (0.3 mm) will be difficult to weld.
Another problem is that the steel, being way more conductive than the refractory that surrounds it, will expand and create stress on the refractory. I've cracked cast refractory sections twice this way using a 0.9 mm round flue. I now make sure that there is enough room surrounding it to allow for expansion. But I think at 0.3 mm it shouldn't be a problem.

[n8huntsman]

Re: Thermal Break Options for pouring concrete landing up to cooking floor

A stainless steel section fabricated as shown in your drawing should be a good solution, although thin stainless (0.3 mm) will be difficult to weld.
Another problem is that the steel, being way more conductive than the refractory that surrounds it, will expand and create stress on the refractory. I've cracked cast refractory sections twice this way using a 0.9 mm round flue. I now make sure that there is enough room surrounding it to allow for expansion. But I think at 0.3 mm it shouldn't be a problem.

So would you go with a full 4.5" row of IFB or use a thinner layer of cal-sil?

[david s]

Re: Thermal Break Options for pouring concrete landing up to cooking floor

So would you go with a full 4.5" row of IFB or use a thinner layer of cal-sil?

I wouldn't use either because I believe the primary reason is to make an expansion joint to prevent cracking of the outer shell/ decorative arch, reducing heat loss via conductivity is of secondary benefit. If you are using either cal sil of IFB's as an insulator then there is little difference. Cal sil would be a marginally better insulator.