Announcement

Collapse
No announcement yet.

36" build in heart of Europe, Czech Republic

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • mrotter
    replied
    Originally posted by david s View Post
    Spraying the surface infrequently is far less successful than keeping it constantly wet for damp curing. A superior method is to wrap the whole thing in cling wrap so it’s sealed up. Keeping this on for at least a week enhance the strength considerably.
    Yes, I know, I have it covered all the time, especially in this hot weather.

    Leave a comment:


  • david s
    replied
    Spraying the surface infrequently is far less successful than keeping it constantly wet for damp curing. A superior method is to wrap the whole thing in cling wrap so it’s sealed up. Keeping this on for at least a week enhance the strength considerably.

    Leave a comment:


  • mrotter
    replied
    Originally posted by david s View Post
    It is best to do all of the drying fires before any outer render layers are applied. Otherwise any moisture left in will be much harder to eliminate. 1.5” (40mm) thick render is very thick, I only do mine 10-15 mm with random AR glass reinforcing fibres. The outer shell is only a weather protection and to stop damage to the insulation.
    I did basic render yesterday. The brick and mortar was really really dried out, trust me, it stayed on hot sun for weeks, covered for rains.

    As for render, maybe it is wording thing, but it is rather "concrete enclosure/shell", there will be one extra thin layer of silicone-based coloured render. I had some real bad luck yesterday as I was interrupted TWICE by rain and had to work hard to finish job, I ended in 23:59 MIDNIGHT!!! As for thickness, I believe I ended on average between 2-2.5 cm, some spots likely have thinner layer of concrete, around 1 cm maybe. If I used some special stucco material, I could likely go with thinner shell, but with pure concrete I feel the thickness is just about right. I also used reinforcing fibres, seems to work really nice.

    As for moisture, during rendering I installed plug which can be opened at the very top of dom and I will have that opened during drying/curing process, but in overall, I do not believe I will need many extra curing fires. I will let it sit for two weeks now and likely apply concrete hardening solution (sprayed aerosol) to increase strength. Will provide photo soon, so far no cracking, my wife got order to keep the concrete covered and spray it with water each 2 hours.

    Also, just ordered SS chimney system pieces.

    Leave a comment:


  • david s
    replied
    It is best to do all of the drying fires before any outer render layers are applied. Otherwise any moisture left in will be much harder to eliminate. 1.5” (40mm) thick render is very thick, I only do mine 10-15 mm with random AR glass reinforcing fibres. The outer shell is only a weather protection and to stop damage to the insulation.

    Leave a comment:


  • mrotter
    replied
    Insulation on. Btw, even this unfinished chimney IS DRAFTING smoke just fine. I was shocked to see that even this semi-done chimney works good. Smoke went through chimney and not front.

    First fire: https://www.youtube.com/watch?v=63QX_ecgWSM
    Last edited by mrotter; 06-29-2022, 12:51 AM.

    Leave a comment:


  • mrotter
    replied
    OK. I applied 3 layers of blanket, 3" in total. I am about to apply concrete render of about 1.5" thickness.

    I already laid two courses of brick chimney, will be ordering stainless steel single wall chimney system which will come on top of it.

    Also, made first curing fire yesterday and even incomplete chimney of about 30 cm length DID draw smoke out of vent arch! Huge satisfaction.

    Will post photo/video soon.

    Leave a comment:


  • mrotter
    replied
    OK, made progress. Built vent arch, which is free-standing. All surfaces of vent arch which are facing to main oven dome are separated with 1-2 cm of space which is now filled with blanked insulation. There is very big heat brake gap incorporated into floor, also filled with blanket. All sides of floor are separated from vent arch also with insulation blanket (1 cm) covered by thin layer of sand.

    Prepping for blanket insulation covering of dome. Dome/vent intersection will be separated by fire-resistant elastic rope.

    Insulation will have 7 cm (3 layers) + 3-4 cm of concrete shell on top of it. Then top finish which will be silicone-based render normally used for houses here. Vent arch will be covered by "flexible" mortar and broken mosaic-like style tiles.

    As for flu, I am about to order 150 mm ID metal chimney pipes which will be placed in square-shaped chimney brick structure.

    After blanketting, I plan on doing some small fires, but overally there is little to no of moisture in the oven as it was left uncovered in shiny weather and covered during rains.

    I plan to make/buy some small decorative statues to be placed on those two small platforms in the front face of vent arch.

    Leave a comment:


  • mrotter
    replied
    Anyway, I went with 3-piece keystone, stones places side by side. Also, I decided to make cuts into casi to make room for free-standing outer/vent arch, similarly like here: https://community.fornobravo.com/for...827#post175827

    So I decided that my outer arch bricks/legs will stand directly on hearth concrete, mainly because tiles/casi contact to hearth was not 100% flat and I was afraid of potential cracking. Will post pics soon.

    Leave a comment:


  • mrotter
    replied
    JRPizza Doing one row with wider bricks prove to be good way. I picked some speed and was able to finish last course today (no mortar between bricks yet). Hole for keystone has about 11 cm diameter, so I believe I will have to go with 2-piece keystone.

    Question is, is it better to make those pieces stacked horizontally or vertically? I believe horizontal (side-by-side) keystones will be easier to cut and place.

    Another bad message for me is that my 3rd bag of mortar is almost empty and I will have to likely buy a new one - either 5 or 25 kg.

    Leave a comment:


  • mrotter
    replied
    Originally posted by JRPizza View Post
    When trying to make the shortest vent possible there are two controlling factors - providing sufficient area to exhaust gasses and feed your chimney, and if using brick enough depth to build a stiff/durable structure. If you cast a vent you can make it pretty short and only worry about feeding the chimney. If you are using brick the "standard" seems to be 1 1/2 bricks deep. My vent is free standing, meaning I have a heat break between it and the oven dome and it gets no support from the dome. I also used L shaped bricks at the rear of the arch that went back over the top of my dome arch that gave me (I thought) a little more stability and area for the mortar to bond to. I don't know what the absolute minimum with brick would be and it probably depends on how stable the base of the arch is (mine sits on CF board), whether you tie the vent back into the dome structurally, and how much load (weight and potential for movement) your chimney structure puts on it.
    Building a vent that is too deep can make getting food in and out of the oven more difficult but many do fine with the brick and a half depth (~13.5"). If you have that much room (10 cm?) to the end of your hearth slab why wouldn't you want to bring the arch our closer to the edge?
    Also, I can't remember if you are going with the recommended 6" minimum chimney diameter?
    Yes, I plan to go with 6" chimney ID, that's about standard for these types of structures.

    Yes, 1.5 brick depth is about standard as I also noticed on many albums. Main thing that bothers me is really easy of access inside the oven. My arch will also be free standing and separated from dome arch by fire-resistant rope + heatbrake in the floor (air gap). I also plan to use those L-cuts.

    I just did not want to make entry arch unnecessarily deep. Some kind of minimal landing would be great. I will do measurements asap and will report back.

    Also, I started penultimate dome course yesterday, as per your example -> 12 cm wide half bricks -> pockets filled with scraps/mortar. Seems to work just fine.

    Leave a comment:


  • JRPizza
    replied
    When trying to make the shortest vent possible there are two controlling factors - providing sufficient area to exhaust gasses and feed your chimney, and if using brick enough depth to build a stiff/durable structure. If you cast a vent you can make it pretty short and only worry about feeding the chimney. If you are using brick the "standard" seems to be 1 1/2 bricks deep. My vent is free standing, meaning I have a heat break between it and the oven dome and it gets no support from the dome. I also used L shaped bricks at the rear of the arch that went back over the top of my dome arch that gave me (I thought) a little more stability and area for the mortar to bond to. I don't know what the absolute minimum with brick would be and it probably depends on how stable the base of the arch is (mine sits on CF board), whether you tie the vent back into the dome structurally, and how much load (weight and potential for movement) your chimney structure puts on it.
    Building a vent that is too deep can make getting food in and out of the oven more difficult but many do fine with the brick and a half depth (~13.5"). If you have that much room (10 cm?) to the end of your hearth slab why wouldn't you want to bring the arch our closer to the edge?
    Also, I can't remember if you are going with the recommended 6" minimum chimney diameter?

    Leave a comment:


  • mrotter
    replied
    JRPizza

    Also I have a question related to "depth" of vent arch. I have around 35 cm to work with but would like to make vent arch rather shallow - 25 cm deep (one brick on longer side). I planned to make entry hole for chimney 8 cm deep and (around) 20 cm wide.

    So that will be 8 cm (hole) + 8.5 cm of brick on each side of hole. Do you think its just okay? From some albums I saw quite deeper vent arches.

    Leave a comment:


  • mrotter
    replied
    Originally posted by JRPizza View Post
    I didn't bother me at the time as it was not on my radar, but now that you mention it they are rather large gaps. Even though I suggested going with half bricks if you want to minimize mortar exposure to direct flame staying smaller is probably the better choice.
    What did bother me (and you can see it in the picture) was when I was "gently tapping" my keystone plug into place I knocked some shallow "chips" from the adjacent bricks. If I was to build again I would make sure I had a little more clearance when inserting the plug and let the mortar help locate it at the proper height vs trying to have interference do the job.
    OK, I decided to go with wider bricks for next course and fill the "pockets" with brick scraps. Given that I am two rows away from keystone, structurally, it is just fine and should hold up just well. However the "pocket" problem will transfer to next-next row as well and will be even more pronounced, so I will cut small triangle shapes to fill those spaces. Then there will be just enough room for keystone, which will likely have to consist of at least two parts, I will see when I get there (maybe around weekend).

    Also, now I have like 10 bricks left so not enough to make vent arch and chimney structures. Now, I need some design ideas as I have to decided whether vent arch bricks will be visible from outside or covered with some final surface solution (broken tiles, silicone/acrylic render, whatever). If they won't be visible I can use reclaimed almost free bricks. If visible, would have to buy new (not that bad, as only limited amount will be needed).

    Leave a comment:


  • mrotter
    replied
    Originally posted by JRPizza View Post
    I didn't bother me at the time as it was not on my radar, but now that you mention it they are rather large gaps. Even though I suggested going with half bricks if you want to minimize mortar exposure to direct flame staying smaller is probably the better choice.
    What did bother me (and you can see it in the picture) was when I was "gently tapping" my keystone plug into place I knocked some shallow "chips" from the adjacent bricks. If I was to build again I would make sure I had a little more clearance when inserting the plug and let the mortar help locate it at the proper height vs trying to have interference do the job.
    I will check how big those pockets actually are on my build and if they will be "manageable", I will fill them with firebrick scraps as well as I could. If they will be huge, I will likely have to make those smaller cuts.

    Leave a comment:


  • JRPizza
    replied
    I didn't bother me at the time as it was not on my radar, but now that you mention it they are rather large gaps. Even though I suggested going with half bricks if you want to minimize mortar exposure to direct flame staying smaller is probably the better choice.
    What did bother me (and you can see it in the picture) was when I was "gently tapping" my keystone plug into place I knocked some shallow "chips" from the adjacent bricks. If I was to build again I would make sure I had a little more clearance when inserting the plug and let the mortar help locate it at the proper height vs trying to have interference do the job.

    Leave a comment:

Working...
X