7. The Final Layer

The final layer.  The oven is complete!  The final layer. The oven is complete! 

So at last we reach the final layer.  Once the insulation layer is dry you can crack-on and finish your oven.

The last layer uses the exact same technique as the first layer so you should be an expert by now. Using the same proportions, mix a batch of sand and clay together applying the good old puddling technique described earlier.  Again, the amount you need depends on the size of your oven but remember that this last layer will require more than the first layer due to the greater surface area you need to cover.  You will also need some spare mix to extend the chimney (if like me you didn’t make it tall enough first time round!) and to keep for filling cracks.  Make “bricks” as before and gradually build-up the final layer. After you have inserted the last brick, pull-up a chair, open a cold beer and sit back and admire your work.  Well done, your oven is complete!  

Next time I am going to provide some pointers on firing the oven so you can get the best use out of it when cooking. 

Finished oven from the front.

Finished oven from the front.


64 thoughts on “7. The Final Layer

  1. Hi Guys, following all the instructions and at the final layer stage cracks developed within 24 hrs. Location is shaded here in Ireland so drying is slowish. I assumed I had too much clay in the mix so reused the mix adding some more sand. Now 48 hrs after 2nd attempt, cracks showing as it dries out. Should I start final layer again or just fill cracks?

  2. Hi Simon great book!Just finished my oven and waiting for it to dry but seems to be getting a lot of hairline cracks.Is this something to be concerned about?I am worried I have not puddled the clay sand mixture enough.I am in England so heat isn’t an issue.

    • Hi Paul

      you will get cracks in the oven. When you fire them they expand rather dramatically and so they have to expand. Don’t worry about it. You can always fill cracks with spare mixture if you keep some in a bag.


  3. I have just built a brick pizza oven, covered with 4 layers of render and vermiculite. Can I light it straight away?

  4. Any thoughts regarding a coat of lime mortar as a weatherproof finish?

    Flexible, breathable and looks good, does anyone have any experience?


    • I have thought about it. It will crack though – these ovens expand considerably when heated. Worth a shot thought if you don’t mind the cracks.


      • What about a layer of insulation wadding over the clay a few inches deep, then chicken wire then the lime mortar? Maybe give some room for expansion?

  5. Since the final layer will take the brunt of the elements, is there something that i can mix into the final layer, or coat on top of the final layer, that will keep moisture out and preserve the oven from rain?

    • Hello Adam:

      I had the same question you do. In reading another book on the subject, it turns out that the only real solution is a roof over the oven.

      A layer of coloured plaster, while possibly enhancing the looks of the oven, will provide no protection from the elements. Any other material that purports to seal the clay will actually shorten the life of the oven since the oven actually needs to “breathe” the moisture produced when baking breads and other foods. Trapping moisture will eventually lead to oven failure!

      So you can either build a roof, or build a small hut (like what you see done for brick ovens) or you can let nature take its course and repair the oven every few years.

  6. thanks for blogging this info. i saw river cottage last week and was v.impressed by the simplicity of this design compared to the usual pretensious all-brick designs. am looking forward to making a couple of these so that i can bake and roast at the same time.

  7. Hi Guys
    Just a couple of points that i have picked up on whilst reading the Blog ! incidentally Simon, your oven looks like the Dogs Kahoonah’s ! whilst Tony asked the question about the possibility of introducing a door and you stating that most ovens have a door ! I was Viewing a you tube Vid last night and the guy who was fronting the Vid stated that when a door is put in place there is a hole (in his door it was a metal plate, with a rectangular cutout along the bottom of the door) he stated that this cutout should be representative and equal in surface area as the size of the chimney’s opening. I would state though, that his oven, he referred to as being a
    “double chamber oven” the difference between yours Simon, and his was, erm I dunno !!!! except when it fired up i thought that it was going to take off ! as there was a flame that came out of his chimney stack that was about a foot above the rim of the chimney, and his chimney extended from the oven by about some 15 t0 18 inches. The guy was called Ernie Wisner and this is a link to the Vid

    The second point that i thought about was that whilst i have been reading all-sorts of info over the last couple of days i also remembered that another guy also stated that it is best to use a door on your oven during the closing down of the oven as it assists in keeping moisture out of the oven which is a no no as it can cause steam during the next firings and this can cause cracking of the ovens walls. Just thought that I might pass on what I have been reading, if nothing else it at least shows myself that I am still able to take things in. I say this cos I’ve joined the Old Farts brigade, and try my best to ward of Alzheimer’s. Cheers for Now and Good Night all !!

    • Thanks for sharing the info Bob. I also get fire coming out of the top of my oven when it is first fired but not to that same degree. I only use a door (and a chimney plug actually) when I am roasting or baking because it helps with heat retention. Glad you enjoy the blog.

      Best of luck


  8. Hi Simon,
    The oven has taken back seat to other work, but I am now starting the dome. This as you know will be constructed with the old fire bricks, the first course has has been layed and I have built the entrance arch. The entrance arch is 30cm high and the oven dome will be 45cm so I think I’ve got the calculations about right but can you tell me if the chimney has to be exactly at the same level as the top point of the entrance arch. All these measurements are crutial to the operation of the oven or so I’m lead to believe.

    Regards Tony S

    • Hi Tony

      the crucial dimension with regards height of the chimney opening is a relative one. Ensure that the opening is not too low relative to the top of the oven roof. You don’t want smoke to recycle back around the oven because it will extinguish the fire. The smoke needs to be able to escape upwards and not pool inside the oven.


  9. Hi Simon,
    Glad to see you’ve understood the design differences of our ovens. I have another question for you now. If the oven is not completely round, but has one flatter side will it effect it’s operation. The area that I am building it in does not allow for a completely round base. The other question is, can a loose fitting heat proof door be used to retain the heat when it has built up.
    With regards to your question about the chimney. Beside the oven there is going to be a BBQ set on a 10mm steel base, it will be set at an 90% angle to the left of the oven door so that burning ash and wood can be raked out and over to the BBQ base. There will be a 185mm dia. x 3metre vertical chimney over the BBQ and I want it to link up with the chimney from the oven. My question about the door arises from your description of the heat experienced at the door mouth. If I have the two heat sources too close I will cook my left arm while I use the BBQ and my right arm when I’m tending the oven. Could be a tragic way to go. I may have to move the two further apart, or invest in a heat proof suit.
    Interested to hear your thoughts.

    Regards Tony S

    • 1. I don’t think the shape will have too much affect at all.
      2. Yes you can use a door, in fact most ovens do. You just need to be careful that the fire doesn’t extinguish.
      3. I wanted to advise you to invest in a heat-proof suit just so we could see the pictures – ha!

      Best of luck and don’t forget to take some pics we can share on the blog.


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