Old red clay solids as firebrick alternative
Red Clay Bricks
Substitute for firebricks can be old red clay solid bricks. In ovens these alternative red clay bricks will heat up, retain heat, cook, bake, roast, re-fire, absorb conduct store and hold the heat from wood fire and perform the same way as proper refractory firebricks do. If you can not locate fire bricks where you are or for any reason obtain them, Red Clay Bricks will perform much the same way in wood fire temperature levels and can be used instead.
How do I see it’s the right alternative for firebricks?
The replacement bricks must be of this type, old solids. Clay body is the same on the brick’s inside as it is on the outside. Break or cut one of the bricks you find in half to see what’s in the middle. New products are made out of cheap clay bodies whilst only on the outside a decorative clay slip is applied and then the bricks are fired in kiln – you couldn’t use bricks like that. The right alternate also shouldn’t be burnt, if you saw too much black-carbon color in the center don’t use such brick – it would be either over fired and brittle or made out of lesser quality clay. But a few little burnt spots will be fine. 
Working with red clay solid bricks is equivalent to work with refractory firebricks, all matters remain the same only bricks are different.
Where to find these old red solid bricks?
Look around in demolition yards for instance they often stock these red clay bricks. Read advertisements in papers, people very often sell for fraction of price or giveaway exactly this type of old bricks, and other great building material left over from other projects or from cleaning up. There are always few firebrick replacements to be seen here you just have to watch it. Bricks are old and in used condition with some chips and cracks, you can turn them with better side towards hot face, the oven inside. You can buy 200 to 1000 of red clay bricks even for 20 or 30 bucks in total and end up having a lucky day.
Interested in firebricks physical properties or soapstone (soaprock) technical data?
These reds have a great character in eyes of many including me. Often people wants to just get rid off them. Some sellers are obviously aware of the value and the beauty these red bricks have, and so they resell them with profits. By the way these old bricks can be easily cleaned with hammer and brush because in the past brickies didn’t add much cement into mortar if any, mostly lime was used those days.
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Firebricks are costlier too.
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There is nothing better than a pizza made in a wood oven, nice tips. Thanks for sharing.
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This is a great idea. Not only are you using quality bricks, but you are able to used recycled materials.
pays to live green’s last blog post: Maryland Environmental News: October 2008
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I absolutely love pizza, but only the best pizza’s come from a wood oven, there is just something about it that gives the pizza its great taste.
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I got these same old red clay solid bricks from our neighbor for nothing but there were that many I can build the whole oven structure out of them. The outer color of the walls and chimney will have real character. These house bricks certainly are very easy to clean from the old mortar just as you describe, it just simply pops off from the brick when touched. Still for the firing and cooking part on the oven I am ordering new firebricks from a supplier.
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Here in Denmark most old houses are built from those bricks, so obtaining these bricks should be no problem at all. There are even some producers still of ‘old’ style bricks that produce handmade bricks to use when in need for old houses. They could be a nice alternative if you dont want to look at the weathered old bricks, but still want an old style looking oven.
For info only, I guess shippting them to AU, would be insane.
Lars’s last blog post: Hindbærsorbet
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Are you planning to blog more on this topic. I would like to learn more.
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I would buy used firebricks and red-clay bricks. Maybe for some purposes it’s ok but not to build anything solid.
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I remember that my auntie made a grill from red clay bricks. She put a few red bricks one on another along two sides of the camp-fire and put a sheet metal on them. It was the simpliest grill I’ve ever seen. And the best, also.
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I am trying to locate some bricks originally made by you
it is the Brindle {Brindel} not sure of the spelling. Could you please tell me where could locate some. I am in Taunton in Somerset.
Many thanks,
Roger Rossiter
RR BUILDING MAINTENANCE LTD.
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Red Clay Bricks are awesome. I got a whole bunch of those for free from a friend recently and they really perform extraordinarily. Highly recommended.
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There are a lot of Red Clay Bricks in my neighbourhood. I like buildings made of red brick, but some of them need to be just washed up, cause red bricks easily catch dirt from the air.
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I have a whole lot of IFB’s ( Insulating Fire Brick of the rating K23 and K26. They are of the softer type than the solid hard type which have a maximum range of 3000 Deg F.. I do want the bricks to hold the heat for cooking the pizza and breads. Should I just use my red…solid bricks instead and just use the IFB bricks for insulation. I just don’t want to chance having my bricks spalling or something terrible like that! Please…What would be the best thing to di?
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Boiler red clay brick bed material and fireclay, all types of new and recycled for reusing old refractories.
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Dean , do not use your IFBs on the inside , they are great under the floor but have hardly any of the mass you want to make your oven work. Sell the extras to a potter or blacksmith and use perlite or vermiculite for your pour in insulation . if you can afford it ceramic fiber is an excellent 1st layer on top of your bricks
tim
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Hi Rado,
I am a little puzzled, but also content with life. I was hoping you could educate me as to why one type of brick is better than another when building a brick oven.
Will dry-pressed solids (hope I have used the right term), which are fired at 1000˚C+, be good enough, and last a long time, when used for the cooking floor and the dome? Or should I use fire bricks? I have very limited resources, and would have trouble affording fire bricks. What do you think?
Thanks in anticipation,
Nick.
PS: Love the website.
added by Rado:
Hi Nick,
Thanks for the note. This question is often asked so I will write about it a bit extra.
Inner cooking/firing part though is most often made out of firebricks, they have the right material body and withstand reheating or continuous usage. If it’s only a decorative house brick it will not work. House bricks are mostly fired in kilns into high temperatures so they get brittle and won’t absorb water which is logical for the building purpose.
When firebricks are manufactured a completely different clay body is used, they are fired into much lower temps, they also absorb lots of water. When you dip firebrick into a bucket with water you will literally hear how rapidly it absorbs the water in because these bricks are porous. Often the old solid red-clay bricks described above are being used for this purpose as alternative instead of proper firebricks and they work fine.
Like an unglazed bisque clay but strong, these reds absorb water as well. They perform well in this temperature range. However, they should be the correct clay type (real old type clay solids not an imitation for a clay), so the material won’t start pealing down in the heat and continuous reheating as per using the oven.
HOWEVER I know of also house bricks produced now-days that are suitable alternates for firebrick for building wood fired ovens, and come at 3 times lower price. E.g. are the Midlands cream color solid bricks produced in WA (I must place a picture of them here.)
If you knew of some brick type thinking they could be used, or if you are offered some bricks, first cut or brake one in half, wash any dust off with water and look for a white coarse sand in the clay body. You cannot miss to see this sand in. Also they should have NOT: color slip applied on the outside (usually up to 5mm – 1/4″ deco clay slip thickness whilst the inner main brick body is made out of a cheap stuff) and they should not be burnt in the middle at all, usually seen as black carbon color. The bricks must be made from correct clay, NOT from cheap material or masonry like cement based.
So, the part of the oven that faces the heat should be built out of heat resistant clay bricks, and the outer parts of the oven can be normal house bricks, blocks, stones, etc.
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Here in the States, the Germans who settled in Pennsylvania, brought with them the custom of baking in a ‘full-arch’ brick, and lime mortar wood fired oven. They are commonly called ‘squirrel tail’ ovens, since they were build on the outside of the back of a ‘walk-in’ fireplace. The ‘squirrel tail’ is really the flue that is placed in the back, away from the from arched brick door opening. The flue then arches over from the rear to the front, and about 5-7 courses above the opening. This facilitates the passage of smoke above the face of the user. The usual height was about 70″/179cm. A large brick was used to close off the flue, once firing temps were reached, and the ashes went down a specially placed loose brick just inside the oven door arch. The ash pit was then used to collect/store them for future use in soap making..(‘potash’..!). I can answer specific questions thru the aforementioned website. Thank you.
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Lucky you, if the old mortar just “popped off”!!! My husband and myself spent hours trying to remove the mortar cleanly from the red bricks we have. What a mission!! We even got hold of some acid, which still didn’t remove the mortar, but at least the red came up brighter. It is in our experience, a pig of a job!
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I am from South Africa. Can you maybe tell me who in South Africa sells this firebrick product with the relevant Contact Details.
Tx
Jacques
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Hi guys,
I am finding it real hard to locate any of these red clay bricks in Sydney. Does anyone know where I can get them? Is there a sure way to know if they are the right bricks? A few places I have called have asked me to come and see (they seem more confused than I am) – but I am not sure exactly what I am looking for.
cheers,
Mil.
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I used a mix of new and old but pure clay pavers, only pavers were used for wood oven I built according Rado’s masterly tail design dvd with the construction plans, and it works fantastically well. The pavers get perfectly hot and conduct and retain heat as firebricks would I suppose.
Anyone knows where to locate the old railways timber sleepers in Victoria? I plan to recycle them into an outdoors furniture.
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What type of pavers did you use? Can you please identify them? Are the pavers differed to Red Clay bricks?
I am so confused.
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Hi there,
Thanks for the great tips. I was worried about the cost of firebricks as such I am pretty happy to hear that the old red clay bricks will do the job.
One question I have is in regards to the mortar I should be using to mortar the old red clay bricks. In my case, you wont see the brickwork as it will be inside the oven, hence the colour is not an issue. I am concern that my mortar mix may crack up and all my hard work will be to no avail.
I would appreciate any tips. Thanks again, Jason.
PS. or am I best to dry stack the red clay bricks where possible????
added by Rado:
Hi Jason,
In the firing chamber I dry stack bricks in the hearth floor and in walls also. In such a case where bricks have uneven dimensions, or if they are slightly chipped damaged, a very thin heat resistant mortar application is used to fix the differences. For this fix it’s better when premix refractory mortar is used because the type can be very thinly spread onto the bricks without drying up fast. When comparing it to a fireclay based mortar (with sand plus lime mixed in or plaster), which is better for thicker applications (but bricks need to be soaked in water before working with fireclay based mortar.) Premix commercial does not cost a lot at all per 1 bucket, also very little of it used used up on one oven job, less than one bucket. You could use it with the recycled red clay bricks as well, also in arches if you are concerned; up to the point where the “V” gaps between bricks in arches get wider. Up to one 3rd or one half roughly. The rest can be wedged with brick fragments pushed into the mortar, not sparingly, rather many fragment pieces – the more of them goes in the better as there will be again less mortar in the gap. Or quick cut little wedges with diamond wheel. Is that what you needed? Have you seen these pages? :
http://www.traditionaloven.com/1393/mto-firebrick-arches-part-two
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Cheers Rado, great info there, much appreciated. I’m looking forward to having a go and I will let you know how I go.
Just one thing actually, I’m guessing there is no need to soak the old red clay bricks in water before using the premix commercial refract mortar, or would recommend doing so.
Thanks again. Cheers, Jason.
added by Rado:
Hi Jason,
Sure, with commercial premix, an Air-Set type products, you can spread the mortar straight on the dry bricks. No need to soak the bricks in water nor wet with water. Just make sure you thoroughly mix the mortar content before use, all the way from the bottom of the container in which you buy it. It’s important to mix it well.
Also, read the directions of use on the bucket, as these mortar products differ a lot (in case as someone might be selling a natural clay based mortar).
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Hi guys,
I am having trouble sourcing premix commercial refractory mortar here in Adelaide. Traditional brick ovens stock it here in Kent Town but its $60 for a 25kg bag. Is that the norm???
Hey thanks again for all the suggestions Rado.
Cheers
Jason
added by Rado:
Hi Jason,
The price will be very similar elsewhere. You will only use one bag of this mortar. I buy already premixed fire resistant mortar in bucket roughly at $40, and that amount is plenty for 2 ovens.
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Refractory fire bricks are capable of sustaining intense heat and without fusion nor deterioration at or around their operating temperature. Fire bricks usually contains aluminum oxide and silicon dioxide but most known silica and alumina compounds. The manufacturing process involves baking the bricks in high temperature industrial kilns, which themselves have firebrick linings on the hot face, to create a vitrified ceramic or refractory products.
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Found mostly in brick alike rectangular shapes, these clay bricks are used to build the hot-face interiors for pits, low heat furnaces and many indoors or outdoors ovens. As these clay bricks are somewhat heat resistant as well, they are quite useful to build fireplace hearths in homes and outdoor areas.