Masonry heater stove - stove top help

Hi all, my first post, but many months of reading the great forum. Hoping for help with stove top materials, and what'd be best for my stove.

I've built a masonry heater/stove based on Max Edleson's wonderful cabin stove design:


I don't know what to use for the stove top, what would everyone recommend?

Here is the cabin stove:



In the construction, I've used old clay bricks, Victas fire cement, Victas fire bricks for the fire chamber, large fire clay slabs for the pizza slot (I'm not actually convinced the pizza slot will get hot enough to cook pizza's but I'll find out in due course! I've got hold of a great cast iron door to mount on the front. I've made this primarily as an outdoor fire, to have outdoor seating around it and eventually a pergola. It will be a social area for summer evenings

The required stove top dimensions are:
70x58cm
28x23"

I want to put the top onto the stove, will use fire rope and potentially some stove mortar.

From reading the forums I think I have the following options and would appreciate your help

1. Cast iron slab
Pros - heavy, stores heat, potential to cook on it
Con's - it seems expensive and difficult to source
Questions:
- I'm not sure what size / depth of cast iron I'd need 5mm/10mm/50mm etc to ensure it doesn't warp
- Will it rust? The fire is outside, UK rainy weather.

2. Steel slab
Pros - looks abit cheaper than cast iron (I've found this Steel Plate Black CQ 20MM at https://www.metalsupermarkets.co.uk) for £150
Cons - not sure...
Questions - Would it be as good as cast iron for cooking / retaining heat / cooking on?
- Would it be more susceptible to bending/warping from the heat?
- Is there a special type of steel I need
- Will it rust? The fire is outside, UK rainy weather.

3. Concrete - is this even an option!? I was thinking a polished concrete top might look good
Pros - I'm guessing it'd be the cheapest option.
Questions:
- I'm guessing I can't cook on it?
- Would it be more susceptible to cracking from the heat?

4. Thick glass - is this even an option!? I've seen the tiny house cook stove heater plans - https://permies.com/t/71700/Tiny-House-Cook-Stove-Heater - this could be an option but I'm not clear on the pros and cons of using glass and it looks like it'd be tricky to mount.

5. Is stone an option? e.g. granite? Could be cheaper, but not sure of the pro's and con's.

Any other options out there?

Thanks in advance for your help

Hi Nick; Welcome to Permies!
Outstanding stove you have built!   First thing that pops in my mind for a top, is soapstone. Trouble is, a piece large enough is expensive.  

Is your top exposed directly to the fire ? If not I think granite would hold up.

I would not use steel ,  because of the rust, and possible warping.  Cast iron in my opinion (low value) would be better than steel. I would think that for cast thicker is better.


A possible idea to keep your costs down would be to use ceramic fiber board on most of your top and only use a smaller piece of soap stone for cooking.  The C.F. board could be topped with whatever you like. What ever is over it will hardly heat up.

Hi Nick;
Looking closer at your photo's, it appears that your pizza oven is  blocking the direct flame path to the top?  If so it opens up your choices.  Steel will rust, but if kept covered and oiled it should be fine. Any solid slab of stone (thick enough ) would work as well.    Heck depending on temps concrete "could" work.  Cast Iron would be fine.   You could still use the C.F. board. Cover that with clay brick except where you want a cook surface.

Thanks Thomas

Yes the pizza section is large fire clay slabs, they will block the direct flame heat. I've left a gap around those slabs to allow the smoke to rise, it then, hopefully, heads down the downdraft, under the fire box and out the chimney.

Soapstone sounds good - just to confirm, would I be able to cook on it?
It does look relatively difficult to source in the UK

I can get hold of granite quite easily and cheaply in the UK, as there's no direct flame I'm tempted with this option. It'll be easier to source than a cast iron slab. Will I be able to cook on granite?

Yes , soap stone or granite would be fine to cook on.  
I just checked and granite has a melting point of 2200 F or 1200 C. Soapstone is 2900F or 1600 C
Of the two the soapstone would be better but more expensive. The granite would be cheaper and easily replaceable if it has a flaw and cracks.
Myself I think I would use C.F. board covered with brick , then a smaller piece of soapstone.  
Both were rated to be in a direct flame path... in case your pizza oven comes out.

EDIT)    The soapstone actually gets harder after reaching a certain temp !

Hi there, is there a way this stove could be built so you would be able to use it inside?

Christina, welcome to the forum.

I see no reason why that stove could not be used inside with the proper pipe to vent the smoke outside.

That stove is very similar to the Walker Cook Stove:

https://permies.com/t/205948/Walker-Tiny-Cook-Stove-Reflection