Why Fire Bricks ??

[bigal69]

I watched a programme on BBC4 a few weeks ago about kitchens and their importance and in one programme it featured a brick wood fired oven built into the house of a 17th century property.

Now my question is why use fire bricks when I presume the bricks of the day in the 17th century would not be of industrial kiln type linings.

I don't want to go to the trouble of making a WFO out of normal bricks if they only last a few firings but then on the strength of htis programme I cannot see the fire having to be rebuilt often.

At the same time i don't want to buy kiln bricks if I'm going to have to buy numerous blades to help cut them as per the problems others have experienced.

Also cob ovens are only made of clay and straw...

Any thoughts people?

[cannyfradock]

Hello Bigal.....welcome to the forum

Good question...and very valid points raised.

Any ancient ovens would either have been made from a basic clay brick...or Clay...or earth. Many of the real early Wood-fired ovens in Europe may have been influenced by The Romans who knew a lot about refractory properties. "Pompeii uncovered" is a prime example of seeing these ovens being used successfully by individuals and communities......back to the 21st century......

Fire-bricks will always be the best option in maximising your ovens efficiency. As you mention cutting these bricks calls for a diamond blade and the bricks need to be soaked in water before cutting. You can always use a hammer and bolster to cut the bricks as I did on my last Pompeii build... woodovenukforum.forumup.co.uk/viewtopic.php?t=851&mforum=woodovenukforum
Clay bricks would be the next best option...the old "red clays" from the 1920's are perfect as long as you get the insulation right.
Storage heater bricks can also be used but you must check that they haven't come into contact with asbestos (from the 1970's).
Clay is the other option. Stone or concrete bricks should be avoided in dome construction as they will not hold heat as well as clay products and will crack and spall when coming into contact with extreme heat.

Terry

[tonyb]

Al, in answer to your points depends on your answers to a number of core questions:

How long do you want it to last?
What are planning to cook? And how often?
What materials are available locally?
How much do you want to spend?

If you are planning to stay in the house for 10 years and fancy baking pizza, then the durability of fire brick makes it the most attractive (and expensive) option. Only planning on being around for a couple of years, then try a clay wfo.

Of course, the options don't have clear cut envelopes when it comes to what's best for any individual situation, so its difficult to provide clear cut recommendations.

Going back to your your 2 specific points: modern bricks and diamond blades. Most modern bricks are fired at low temperatures which tends to make them less stable to high thermal shock, but its almost impossible to predict with any certainly what an individual brick or type of brick will do, as its also a function of the clay's chemical composition.

If you go with firebricks then you will have to cut them using diamond blades. A pompeii requires a lot of cutting and a barrel only needs a few. I bought a cheap 115mm angle grinder and blades from Maplins about £20 a couple of years back which did the job. So it doesn't have to be expensive but better equipment might make it easier. But then we are back to the circular argument of cheap less durable or expensive, more durable (maybe).

Sorry, I know this isn't helping a lot, and your questions are what most people on the board thinking about building go through. You'll continue going round and round the various alternatives until you finally make a decision, I know I did, but I think answering the question I posed earlier will help you get there.

Until brick manufacturers provide information on the thermal properties of the bricks that they make (probably never happen) then the best you can hope for is experience from someone local to you

[turkey]

I think its important to distinguish between "normal" bricks as we have them now and the bricks from days gone by.

previously bricks where made of pure clay dug from the ground around the area of building, clay is fired at temps over our oven usage and should take the heat cycles quite well.

engineering bricks and the cheaper ones on sale now are a little more of a mixed bag, under the heat they can crack or break down.

I believe we had one experimental oven use engineering bricks with some success but I am not sure the saving on a few bricks outweighed the risk.

there is no magic to the firebricks, their role is simply to absorb during firing and radiate heat during cooking, firebricks are designed to take the heat and store it in kiln scenarios so are the perfect modern building material, they are dense and take a bit of cutting.

some folks use a angle grinder, not being too trustworthy of my own angle grinding skills I spent slightly more, I brought a £30 miter saw from BnQ but found out that wood blades have a larger center hole"bore". My blade was a 30mm bore and it took a while to find a suitable blade as the 30mm bore disks all seemed larger than the 200mm disk size, but ebay came up trumps and I brought a 180mm diamond blade. The combo have torn through bricks with no issues and the disk itself never even feels warm in use, soak the bricks and spray the disk with water whilst cutting to keep it cool and looks as good as new, the miter saw is covered in brick muck but still works. I can't find a link now but it was not a tile blade which I think is why some users have used multiple, but a cheap tile blade is about £8 from screwfix so not the end of the world.

if you get creative and plan ahead you can cut bricks on the cheap, also angle grinders on ebay seem to turn over constantly so if you buy 2nd hand there is a fair chance you can sell it on after for around the same price.