Hello everyone

[savodump]

Hi guys and girls,

I'm Phil, I'm an alarm engineer from northwest England, I'm 35 and I've never built anything in my life until the last month or so. I'm looking to build a Pompeii style 30 or 32" (depending on what I can squeeze onto my plinth) pizza oven. I've had a look through the site and there are some formidable builds. Hoping you guys can join me through the high points and guide me through the low points of my build, I'll be very grateful!

[cannyfradock]

Hello Phil......welcome to the forum.

Not many members create a poll (not many know how to ....I don't), but I've voted in your poll. Not sure if you'll get much response though as unless you cut the most perfect angled cut bricks....or "trapazoid" cuts, then you will not be able to use fire-cement as anything over about 4mm thick will never set using the pre-mixed fire-cement that comes in tubs. The most of us use the homebrew mix of Sand, cement, hydrated lime and powdered fire-clay at a ratio of between 3 and 5 to 1:1:1. Very course sand will use 3:1:1:1 and very fine sand will use 5 or 6 volumes of sand to the 1:1:1 ratio of the other parts. On my current build I used the washed dredged sand which is the standard building sand in my S.Wales region and I used a ratio of 5:1:1:1.....I built the dome last Sunday and took away the dome forms on Monday to clean and point the interior....and the stuff was hard as rock.....I did however manage to scrape off the excess and re-point, then clean with a damp sponge...the white on the bricks is the thin film of cement left from sponging off the surface. A few more swipes from the damp sponge and this would've been gone. A brush with a stiff hand-brush will remove this.....or will be burnt off when the curing fired take place.

Terry

[savodump]

Well it's an absolute credit to you Terry, it looks extremely clean internally.
I think I will end up plumping for the fire clay approach, what amount would you estimate that I would need for a 32" Pompeii oven? I would ideally like to avoid paying carriage twice.
I had read that mortar with a lime content becomes very difficult to work but hopefully I can get it going ok.

[cannyfradock]

Phil

I've edited my last post and changed the pic 3 times while you were posting.

Bit confused now.....you say .. "I will end up plumping for the fire clay approach,"....then you say.. "I had read that mortar with a lime content becomes very difficult to work but hopefully I can get it going ok.

The fire-clay comes in plastic tubs and can only be used to a maximum depth (I think it's about 4mm) ...not sure of the price or quantities needed as I've never used it, but you would have to cut each brick perfect to make sure each brick fits snug against each other. Have a look at the "kilnlinings.com" site for info on price and quantities needed.

If you are using lime, then you will be making up a refractory mortar.....or homebrew mix as adopted from the American name given to this refractory mix. This is a sticky mortar mix, but with clean trowels it isn't that difficult to use.

Terry

[kstronach]

hi phil, i see you found the forum ok!

what size plinth are you working on? as for mortar i used silica sand (i think i read somewhere it was better for use in higher temperatures), hydrated lime, and cement at a ratio of 6, 1, 1. also used some feb (mortar plasticiser) in the mix to make it easier to work with, but a squirt of fairy will do also! i didn't use any fireclay in my homebrew mix due to cost implications but most people do i think, however my mortars still holding up ok.

are you planning on using firebrick for the dome?

when you get crackin be sure to set up a build thread with photos then people can follow your build and you can ask any questions on there.

good luck

keith

[savodump]

Cheers Keith,

I had a really good look over your build, on more than one occasion. I've seen a few ways of putting a plinth together but yours seems very structurally sound without extreme amounts of work or cash, though I'm sure you get a better deal than I do down the builders merchants.

I've got a 5" or just over concrete base measuring 150 x 150 at present and I'm debating how to proceed really. I'm think of building a block wall but with the blocks laid horizontally rather than vertical to provide a little extra load spread and to minimalise the effect of my amateur brick laying abilities. Then lintels and slabs as you have. I'm going to go with thermolite block as the insulation then I have a number of storage heater bricks and a few shallow fire bricks for the oven base.
When dad knocked the chimneys out at his house he put all the claughtons to one side so hopefully I've sufficient (100ish) to build my dome from. It's mainly the mortar that's been concerning me as I don't want it to crack but getting quantities of fire clay is extremely expensive.
Got more than 3m of ceramic wool insulation from eBay at 20 quid so thats all good. Dad has a twin walled steel chimney going spare so it's more a case of planning and assembly really.

[bookemdanno]

Hello Phil, and welcome to the community!

The mortar question comes up pretty regularly, and like what bricks one uses its a matter of cost versus potential for failure. There's also the need for us here to advise the most tried and tested route to not open ourselves up to providing advice that has a higher risk attached to it. Cracks aren't really the problem, as i expect that even homebrew can crack. You just need to follow the simple principles of making sure that the bricks interlock. Look at brick arches with their form of the outside raduis bigger than the inner and the amount of bricks being too many to fall into the area spanned.

The Fireclay Homebrew is a variant of a standard fireproof and high heat mortar, and there are higher specifications too with higher costs. This is the "preferred" and many times over used mortar of choice for over 90% of oven builds on here and Forno Bravo.

Keith just used a pretty standard bricklaying mortar with Lime, and his oven is still standing and working just fine. As i'm sure that many other builds have used, that have not been subject to our outstanding advice and knowledge based here. Although we are managing to help more and more builders, there'll be loads that simply will have done their own thing and just laid bricks.

During my own build i looked into pure Lime Mortars, to act sympathetically with my choice of old victorian solid clays. I used a Natural Hydraulic Lime, and again all is working just fine. The only problem i had was render that was too young to stand a particularly harsh winter. I had contact with a pottery kiln builder and a Lime Kiln builder, who helped me in my choice but it was still a step into the relative unknown. The original wood ovens built centuries ago, would have been likely to have used a lime mortar. However Lime is a more expensive product, due to the building industries reliance on Cement these days.

So, id say, if you can afford that likkle bit extra, go for some Fireclay and use the homebrew mix. Its the safest option. You can get it from Jewsons, or other merchants, or Kilnlinings or other refactory suppliers.
You can save money elsewhere, on things that are less likely to cause you troubles. Or you can take your own calculated risks, and choose your own route of materials. Personally i prefer the more ad-hoc approaches of re-using materials, with its extra bit of the unknown thrown in for good measure, and the research and increase of knowledge it usually brings. Hope this has helped. Just ask again, if you need more help!
regards, Danno.

[savodump]

Cheers Danno,

I work on the principle that all information is good information, it just broadens your mind and your choices a little.
I will get the fire clay I think, just need to work out how much now.
Think I've probably saved enough money with my bricks being free and my ceramic wool being so cheap, I can probably afford to do the right things right!

[kstronach]

phil,

just had a measure up of the platform my dome is sat on, and its 5ft wide by 6ft in length. That leaves me with about 3" to spare at the sides and back and about 8" in front of my opening. mine is a 32" oven so if thats the size you're looking to build thats the size i'd be aiming for . . roughly! you say you've got about 1500mm square concrete base at the moment so you might need to try and gain about a foot more in length to allow for the opening, and ideally you want about 6" of spread around your blockwork on the concrete base. as you'll have seen on my build i cantilevered my flags out to gain a bit more for my oven to sit on which is a good idea if you're tight for space.

regarding fireclay you'll probably only need 2 or 3 25kg bags i would have thought for the dome. as terry said the homebrew mix is about 5 or 6 parts sand to 1 each of lime, cement and fireclay. someone else who used fireclay in there mix will probably chip in and help you out with more precise quantities!

100 bricks should get you a long way but might not quite finish the dome, as you know i used claughtons for my build so they work ok, just a tip wet them all down before you build or they'll suck the life out of your mortar and home brew tightens fairly quickly anyhow! i'll keep my eyes open for some more bricks in case you need any and if i find any i'll let you know. good news on the flue, twin walled is a better choice especially if you plan to render around the flue when it comes to waterproofing the oven.

check out dannos build also, it was a great help to me and he used old red bricks too, and some good info on there.

ukwoodfiredovenforum.proboards.com/thread/67/suffolk-oven?page=1&scrollTo=217

red brick might not be the best compared to fire bricks but i personally think they make a good traditional looking oven, and i've no qualms with mine!

[savodump]

Cheers Keith,

I've ordered some fire clay today and I reckon 3 bags will be plenty. Fingers crossed.
Blocks, lintels and slabs all being delivered today or tomorrow morning so then I can get cracking on. I've extra reclaimed red brick that I can do some of the more architectural and less heated areas like the landing arch, as I don't think it's quite as good a clay as the claughtons. So hopefully my 100ish are sufficient because Bod has been and laid a parking area over the remaining ones from the chimney!
Thanks for the assistance, its much appreciated, I can almost taste pizza now!

[aliuk]

Hi Everyone, I am new to this forum, I have built a outdoor wood stove for cooking and BBQ, I am almost at the end of the build, but I am stock in one part which I need some good advice on it please!
the whole build it made of building bricks and normal mortar (building sand and cement), now inside the firebox( where the fire grate will sit and wood will be burned, I need to pack the sides for the brikes with fire clay, but I have not idea what to mix the fireclay with and what else to mix to it? For example: (Sand, Lime, Cement), can I use normal blue circle cement with red builders sand? And what is the ratio? As everyone gives a totally different reatio, what is the best ratio to use please? Thank you

[downunderdave]

Nov 4, 2022 0:57:10 GMT aliuk said:

Hi Everyone, I am new to this forum, I have built a outdoor wood stove for cooking and BBQ, I am almost at the end of the build, but I am stock in one part which I need some good advice on it please!
the whole build it made of building bricks and normal mortar (building sand and cement), now inside the firebox( where the fire grate will sit and wood will be burned, I need to pack the sides for the brikes with fire clay, but I have not idea what to mix the fireclay with and what else to mix to it? For example: (Sand, Lime, Cement), can I use normal blue circle cement with red builders sand? And what is the ratio? As everyone gives a totally different reatio, what is the best ratio to use please? Thank you

Any areas that are subjected to flame impingement are susceptible to failure if normal OPC Ordinary Portland Cement is used. It begins to break down north of about 300C. To overcome this issue builders use a more highly refractory mortar, typically calcium aluminate cement rather than the calcium silicate that OPC is made of. This is expensive stuff with very short working time. A far cheaper and more friendly to use brew called "homebrew" will suffice. It is by volume 3:1:1:1 sand, hydrated lime,OPC and bricklayers clay. If the OPC does fail then the lime takes over. Should the lime fail (north of 500C) the clay takes over. This mix is cheap and very workable.The cementious content appears very high and some builders go for a 6:1:1:1 because of this, but the reason it is high is that if for instance the OPC fails then a 6:1:1:1 brew is effectively only an 8:1  mix because until the clay reaches sintering point (almost600C) it can only be considered an aggregate and failed OPC also becomes an aggregate if the heat destroys it.

Regarding bricks, Standard house bricks, the ones called wire cut bricks with holes in them are also unsuitable. Old solid red bricks are usually ok, but not for the floor where the fire sits on. The floor should be of firebrick and the bricks are best laid loose to allow for individual thermal expansion and contraction. Sometimes their thickness varies a little or they may be slightly warped, so if required a dry levelling mix of 50/50 sand and bricklayers clay is used. This will allow the free expansion as well as easy floor brick replacement if required after years  of service.