Another new addict

[Triggaaar]

Hi all

Thank you Forno Bravo for the plans you make available and the everyone for the inspiration posted here.

I've found a little space in the garden where I could fit a nice little Pompeii oven. I'm no brick layer, but I'm reasonably handy and think I could manage the build. Budget is a big issue (I can't afford much) and I have a few questions straight off :

Size:
I'd favour building the 36" to make the oven stand out less, and save a little on build costs, but I've read in the plans that FornoBravo recommends a 42" over a 36" size. The shop made 32" ovens I've seen on YT looked to do the job, so I was thinking 36" would be perfect. How much do you need to be cooking in order to run out of space with the 36"? Given that I'll be making it, I suppose another option would be to build it in-between the two sizes (unless that's not worth doing).

Over engineered?
Looking at the plans, and then builds that have followed them, I feel that the oven base is particularly strong, and could handle far more than the weight of the oven (the base is considerably stronger than the 100 year old houses we live in in the UK). I realise that one of the worst mistakes we could make would be to not make the base strong enough, as a little bit of movement later could crack and ruin the oven, but I'd like to consider trying to save a little on materials by having slightly less foundations, or walls without the reinforced steel, or a slightly less substantial top to the base. Has anyone with experience had success making their base slightly less tank like?

Materials
Can anyone recommend a good place for materials in the UK? Particularly the firebricks and mortar, which look like they'll be a substantial part of the costs.

Many thanks
I hope I can at some point post some pictures of another wood fired oven

[david s]

Im a fan of small ovens because its less labour, materials and cost to build. Most owners only cook one pizza at a time because they take longer to prepare than they do to cook. Unless you are running a restaurant a small oven is perfectly adequate for parties up to around 30 people and if you get everyone to share whatever comes out you can feed 80 or so. Regarding roasting, unless you want to cook a whole pig a small over is perfectly adequate for the family roast and for bread, how much can you eat? Unless you want to bake for the whole village or sell at markets a small oven is more ideal for a few loaves. Also the fuel consumption is roughly directly proportional to the volume of the chamber so it also becomes a factor in cost and labour.
Regarding the supporting slab and uprights holding it, you can reduce its thickness if you cantilever it over the supporting piers. (See my profile pic for example)

[Triggaaar]

Im a fan of small ovens because its less labour, materials and cost to build. Most owners only cook one pizza at a time because they take longer to prepare than they do to cook. Unless you are running a restaurant a small oven is perfectly adequate for parties up to around 30 people and if you get everyone to share whatever comes out you can feed 80 or so. Regarding roasting, unless you want to cook a whole pig a small over is perfectly adequate for the family roast and for bread, how much can you eat? Unless you want to bake for the whole village or sell at markets a small oven is more ideal for a few loaves. Also the fuel consumption is roughly directly proportional to the volume of the chamber so it also becomes a factor in cost and labour.

Prefect, thank you. We don't eat a lot and don't have massive parties. I can imagine larger ovens make it easier to push the fire out of the way and have room at the other side for a pizza to cook more evenly with less turning. Or perhaps it would be easier for a roast and side dishes. But if that can be done fine with a 36" (and I guess you don't need a big fire for roasts etc, as you don't need the highest temperatures), then I'll go 36.

Regarding the supporting slab and uprights holding it, you can reduce its thickness if you cantilever it over the supporting piers. (See my profile pic for example)

Cool, I'm just looking at your photos. The one used for your profile is really neat, what size is that?

I assume the cheapest method is to build a clay mix over a sand base, but I'd like to go for a brick igloo, as in the FornoB plans. Apart from that though, I'd like to save on costs where I can.

[Bandit]

Good luck on your build

Make sure you make you base big enough - just adjusting mine at the moment as completely misjudged how thick my walls would be

I based the dimensions for the oven I am building from a friends readymade Busman oven-(costs a fortune but is amazing) it’s only 24 inch internal diameter and can easily cook for 2 families with kids - made a pizza every few mins and was quick to heat up, didn’t need a lot of wood and maintains heat for cooking the next day.
36 inches is huge in comparison.

I bought my firebricks from https://shop.vitcas.com/firebricks-2...m-6-p-asp.html they are £1.68p per brick if you buy 250 or £1.80 for 150. I picked up from victas in Bristol to save costs.
Managed to get splits from eBay for £1 each as well - these were a lot smaller than I expected - thought they would be half the size of standard firebrick but they are smaller. They are a lot easier to split/cut but would have probably been more sensible to get all full-size bricks.

i was going to make my own home brew mortar but ended up buying ready made screed from EBay. Just looked and there’s someone selling 6 large tubs of heatproof screed for £30 which is a bargain https://rover.ebay.com/rover/0/0/0?m...2F222962884128. I paid £50 for 5.

cheapest place for vermiculite was roofers merchant (micafil) used as loft insulation - was £15 for 100 Litres

can also pick up cement cheap from eBay or free cycle as people always buy too much for home diy projects. The chap I got my cement from asked for £5 for 10bags and was just happy to clear his shed out.

[Triggaaar]

Good luck on your build

Thank you.

Make sure you make you base big enough - just adjusting mine at the moment as completely misjudged how thick my walls would be

Did you start before you had plans from here? I think if I allow what they recommend, I should be ok. Maybe add an inch all round to be sure.

I based the dimensions for the oven I am building from a friends readymade Busman oven-(costs a fortune but is amazing) it’s only 24 inch internal diameter and can easily cook for 2 families with kids - made a pizza every few mins and was quick to heat up, didn’t need a lot of wood and maintains heat for cooking the next day.

Impressive, and like you say, 36" is huge. I wonder why they recommend 42" then? Of course it will be right for some people, but for everyone who has enough space?

I bought my firebricks from https://shop.vitcas.com/firebricks-2...m-6-p-asp.html they are £1.68p per brick if you buy 250 or £1.80 for 150. I picked up from victas in Bristol to save costs.

Yeah I've seen those - I hadn't even thought of picking them up. I did a search and found quite a lot of suppliers, but recommedations on the quality would be good. Some of the results:
https://www.firetile.co.uk/shop/fire-bricks/
https://www.kilnlinings.co.uk/Kiln-Linings/Firebricks
https://shop.vitcas.com/all-products/fire-bricks.html
http://firesparesonline.co.uk/index....ze-fire-bricks
http://www.armstrongbrickovens.co.uk...PizzaOven.html

That last place has the standard bricks (230x115mm, with varying thicknesses. They also have cut bricks for the igloo itself. They are:
50 x 115 x 65mm and
75 x 115 x 65mm

Obviously the 65mm is the height. Is the idea that you use the 115mm (4.5") as the depth, but with 2 or 3" width? Sounds quite good, as saves some cutting.
The same place also does floor bricks in 4 pieces, which I like the idea of (although I'm not so keen on the dark grey), as one thing I'm concerned about is getting the oven floor perfectly flat, so the peel doesn't catch:
http://www.armstrongbrickovens.co.uk...ng_Floors.html

i was going to make my own home brew mortar but ended up buying ready made screed from EBay. Just looked and there’s someone selling 6 large tubs of heatproof screed for £30 which is a bargain https://rover.ebay.com/rover/0/0/0?m...2F222962884128. I paid £50 for 5.

cheapest place for vermiculite was roofers merchant (micafil) used as loft insulation - was £15 for 100 Litres

Will take a look, thanks.

Thanks for the help.

[david s]

My oven is only 21” in internal diam

[wotavidone]

Those pre-cut bricks give you lots of options really. If you wanted to you could use them to make 2", 2 1/2", 3" or 4.5" thick dome, depending on which way you oriented them. But, looks like they'd work out fairly expensive.
I have a 750mm/29.5 inch oven. If I was building again, I would make it a little bigger. However, that is because I want to do more things with it.
I don't quite subscribe to David s' 21" size, as I find the required skill level rises as the size falls, but I do agree that big isn't necessarily better when you are building an oven.
I've been involved with building and using several ovens now, and I don't see any amateur, no matter how skilled, trying to do more than one at a time regardless of oven size.

The biggest oven I have assisted in building and using is 900mm/36.5". It is seriously roomy compared to mine. You'd need a big pizza party to need anything bigger than that.

[Big AC]

Can anyone tell me if it matters if the half bricks for the dome wall have to be placed on there thickest side of 4-1/2” or can they be placed vertical which only gives you a 2-1/2” thick wall and less bricks.

[wotavidone]

I did that with 50mm/2 inch bricks.
https://community.fornobravo.com/for...039#post183039
It heats fast, didn't need as many bricks, doesn't hold as much heat for retained heat baking as I'd like.

The next oven I assisted with was done with 75mm/3 inch bricks on their sides.
https://community.fornobravo.com/for...826#post233826

That is a better oven to use I reckon. The extra inch of thickness means 50% more mass.
The other thing is, we were using fired clay pavers, as firebrick is just way too expensive here in Australia.
They are not as dense as firebrick. So both these ovens are way less mass than a 4 -1/2 inch thick firebrick oven.

If you are using real firebrick, I'm going to go out on a limb and say yes you can get away with making it 2-1/2 inches thick.

BUT:
- It isn't as stable as a dome made with half bricks laid on the flat

- Strongly recommend you taper all bricks so as to get a good fit. There goes your wastage - off-cuts everywhere so the number off bricks saved is not directly correlated with wall thickness.

- Less mass = less retained heat baking. Unless you are a 100% pizza fanatic you WILL want to do bread, slow roasts, etc

- The difference in mortar use is not directly correlated with wall thickness either - you find yourself stressing over stability and structural integrity and putting a layer of mortar over the whole lot "just in case". I built a 4-1/2 inch thick dome with another mate - didn't have any of those sorts of worries.

- Having cooked in all three of the ovens I've been involved with building, I reckon the difference in heat-up times and fire wood use is not as big as people might think

[david s]

The problem with laying the bricks on their sides is that there is less width of mortar joint holding the bricks in together. While you can get away with a standard brick laid on edge (3”), a 2” thick brick paver laid on edge is too thin and as reported by others, gives problems down the track. Backing up the bricks with another layer on top is a good idea and adds the required extra thermal mass.

[Triggaaar]

The problem with laying the bricks on their sides is that there is less width of mortar joint holding the bricks in together. While you can get away with a standard brick laid on edge (3”), a 2” thick brick paver laid on edge is too thin and as reported by others, gives problems down the track. Backing up the bricks with another layer on top is a good idea and adds the required extra thermal mass.

Usually you'd use half bricks, and when laid they'd be 4.5" wide, 4.5" deep, and 2.5" high. What would you think the the pre cut bricks arranged to be 4.5" wide, 3" deep, and 2.5" high? Obviously less thermal mass, but as whatavidone says, probably enough (he compared to ovens built with less thick fired clay pavers).

Also, a lot of shop bought ovens have a lot less thermal mass than a 3" firebrick.

[Triggaaar]

I did that with 50mm/2 inch bricks.
https://community.fornobravo.com/for...039#post183039
It heats fast, didn't need as many bricks, doesn't hold as much heat for retained heat baking as I'd like.

The next oven I assisted with was done with 75mm/3 inch bricks on their sides.
https://community.fornobravo.com/for...826#post233826

That is a better oven to use I reckon. The extra inch of thickness means 50% more mass.
The other thing is, we were using fired clay pavers, as firebrick is just way too expensive here in Australia.
They are not as dense as firebrick. So both these ovens are way less mass than a 4 -1/2 inch thick firebrick oven.

If you are using real firebrick, I'm going to go out on a limb and say yes you can get away with making it 2-1/2 inches thick.

Reading through your first thread now, looks great. I'll read the other too.

BUT:
- It isn't as stable as a dome made with half bricks laid on the flat

You built the 2" version 6 years ago, has that been unstable in any way? Cracked or fallen apart?

- Strongly recommend you taper all bricks so as to get a good fit.

Would you recommend that even if using the larger half bricks, or are you just recommending that for smaller ones?

[wotavidone]

Reading through your first thread now, looks great. I'll read the other too.

You built the 2" version 6 years ago, has that been unstable in any way? Cracked or fallen apart?

No, it hasn't but when I built it I got cold feet and encased the 2 inch thick dome in home brew mortar reinforced with chicken wire.

Would you recommend that even if using the larger half bricks, or are you just recommending that for smaller ones?

With half bricks laid on the flat, don't have to taper unless you are keen. They are only 2.5 inches high when laid on the flat, so the little vee between bricks isn't all that big.

Usually you'd use half bricks, and when laid they'd be 4.5" wide, 4.5" deep, and 2.5" high. What would you think the the pre cut bricks arranged to be 4.5" wide, 3" deep, and 2.5" high? Obviously less thermal mass, but as whatavidone says, probably enough (he compared to ovens built with less thick fired clay pavers).

Also, a lot of shop bought ovens have a lot less thermal mass than a 3" firebrick.

3 inch thick fire brick would be OK I guess, especially if very well insulated.
This is an example of what can be done. I reckon this is one hell of a good oven.
https://www.fornobravo.com/product-s...k-pizza-ovens/

Shop bought ovens with less than 3 inches off castable are usually made with very dense material, and if you are lucky very well insulated.

[Triggaaar]

3 inch thick fire brick would be OK I guess, especially if very well insulated.
This is an example of what can be done. I reckon this is one hell of a good oven.
https://www.fornobravo.com/product-s...k-pizza-ovens/

And that's only 2" thick!

With the benefit of heating up quickly, maybe 3" is a nice middle ground.

[wotavidone]

And that's only 2" thick!

With the benefit of heating up quickly, maybe 3" is a nice middle ground.

yep. a bit light on if ordinary bricks, good middle ground if firebrick
But, I don't think you are going to save much if you are looking at the pre-cuts still. Seem to be paying a lot for the cuts.