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Post by rhodrigo27 on Jul 24, 2012 15:45:25 GMT
Hi all,
i have been meaning to build a pompeii oven for my mum for ages, and after a lot of stick from her and my family I finally got going the past few weeks. we have a limited space in her garden and we plan on building the WFO with a 34" interior,
I have my slab on which I am building on down and set, and just received my order from Kilnlinings yesterday. Plan is put down insulation board, sand and fire clay bed to lay the oven floor on, build on top of the oven floor, insulation blanket over the top, chicken wire and render using more home brew and seal it in at the end.
I need to go out and get my home brew mix, Now a quick question is the amount i will need? for the building of the dome and arch and for rendering? I would rather have too much than too little and if I can buy in bulk it could save money rather than going back.
any advice is more than welcome and thanks in advance!
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Post by cannyfradock on Jul 24, 2012 17:19:28 GMT
Hello Rhodrigo....welcome to the forum. Your planning sounds good. The only difference to most of our builds is....we put a layer of vermecrete (vermiculite, cement and water) on the insulating blanket, before applying the finisher render coat's. The vermecrete is difficult to apply, but it acts as a fire-stop.......sending the heat back into the dome and it forms a solid crust which can easily be rendered. The homebrew is mixed up at a ratio of 3 or 4 parts sharp sand to 1 each of powdered fire-clay, hydrated lime and cement. For your 34" Pompeii you will probably need 1 bag of hydrated lime, 2 bags of cement and 2 bags of powdered fire-clay.......and sand. Hopefully Liam has advised you to buy powdered fire-clay along with the bricks.....he's very competitive with his prices. If you haven't already got powdered fire-clay then it shouldn't be a problem......living in Sheffield...to buy some. If you still need basic building materials then the Jewson "forum discount account", may save you a couple of bob... ukwoodfiredovenforum.proboards.com/index.cgi?board=membersdiscounts&action=display&thread=82 Terry
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Post by rhodrigo27 on Jul 27, 2012 9:48:17 GMT
Terry,
thanks for the response, in terms of the vermecrete layer i have two questions. what thickness do your recommend for this layer? and how much material would i need?
thanks for the advice on the home brew, I did get fireclay with my order from Liam and yes I am using the Jewsons account as it was cheaper than any where else and is only 10mins away from me! Thanks a lot for sorting that out!! picking up materials from them this afternoon after work and starting after that!
I will update with some pictures as I go this weekend, I plan on getting done the oven floor and planning out this afternoon / evening. Then commencing the dome tomorrow and sunday.
Thanks again
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Post by bookemdanno on Jul 27, 2012 12:06:25 GMT
Good luck Rhodrigo, looking forward to the pictures!
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Post by cannyfradock on Jul 27, 2012 15:44:37 GMT
Rhodrigo
"thanks for the response, in terms of the vermecrete layer i have two questions. what thickness do your recommend for this layer? and how much material would i need?"
If you are talking about putting it under the fire-brick hearth, then 2 100ltr bags will be enough for a 4" base.
If you are talking about a layer on the dome, then 3 bags will probably give you a 3" (ish) coverage. If you are using insulating blanket, make sure the blanket sits snug on the dome......even if you have to use a long bladed stanley knife to slice out some wedge shaped insulation to make the blanket sit tightly on the dome......the exact opposite can be done if you have any gaps.
In the few builds that I have done, I have tried to lay the vermiculite layer on the dome free hand. It's a bit of a nightmare starting off. I have seen other builds where people have bent a piece of hardboard around the base of the dome (about 3 or 4" high) this is a good idea as once you have the base ring of vermecrete, it is easier to build up from.....if that makes sense.
Our members have come up with varying ways of mixing the stuff. My fav. is to empty the vermiculite into an empty 1 ton sand/ballast bag....and add water the night before. The next day add the cement pull the bag from side to side to mix the stuff.
Terry
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Post by rhodrigo27 on Jul 29, 2012 22:26:42 GMT
Hi all terry thanks for the advice, I was wanting information on the dome layer of vermecrete. what would the downsides to not having this layer? as I was tight on space as it was! I am presuming more heat loss? and a higher external temperature? which could cause cracking of the render? Just to up date everyone, I have started! much the the relief of my family,I have layed the base down and got the first two courses down too here are some pics my low riding battered car, handled all the sand, cement and lime ok though! cast slap put up a marquee!! Stash of bricks practice layout of the floor floor set on fire clay and sand (1:1 ) with the front bricks cut Note; for the cutting i bought a 230mm diamond edged blade from screwfix for £13. and have it on a cheap 230mm clark angle grinder i got from machine mart for £47. seemed to cut very well, but glad I soaked them first as other members advised! pic of practice first layer, getting it set out and planned in my head more than anything else. for some reason (probably the cement and gloves) I didnt take any more pictures... but I will take some on tuesday ( my next build night) and give a further update weds! thanks for stopping by!
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Post by cannyfradock on Jul 30, 2012 7:34:46 GMT
Rhodrigo
Great start.....I love the herringbone hearth.
If you are tight for space on the dome insulation I would still try to get a layer of vermecrete on the dome......even if you was only able to use 1 or 2" of thermal blanket. The blanket will insulate your bricks, but the vermiculite will also act as the heat-stop. If I was ever in a situation where I had to choose one or the other, the choice would have to be vermiculite.
Normally people buy a standard grade of vermiculite, but if the layer was quite thin, then try to get the finer grade vermiculite. You could then add a little more water along with a shovel of lime(and cement...like normal) and apply it like render. The blanket must be sitting tight on the dome (but not compressed) and be covered with chicken wire.
The only concern I have is that you have laid your base on a "banking". We get many members saying that they have problems getting enough heat into the hearth after laying the base/slab on solid ground. Normally I wouldn't recommend laying a DPM (damp proof membrane) on top of the slab as this may cause "sweating".......in your situation this was the correct thing to do and your cal-cil board should protect the hearth from a permanant damp/cold slab.
You may also want to put some strips of "kingspan" around the sides and back of your slab to protect it even if it means taking a bit of the dry stone wall down and rebuilding the edge of the stone 4" further away from the slab.
Please don't be put off by my comments. They are just suggestions to make sure you get the best out of your oven once it's built.
Terry
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Post by rhodrigo27 on Jul 31, 2012 8:26:29 GMT
Hello,
Terry thanks for the response, I am all ears for advice on what to do. I had to change a lot of the designs here to fit in the garden and within a tight budget. Fortunately I have some spare Kingstown in the garage so I can add this round the back and sides!
If I can get a good layer of vermecrete on can I just masonry paint on top of this? If that is the case I could get a 2 inch + layer on.
Hope toget some work done tonight but the weather looKs against me!
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Post by cannyfradock on Jul 31, 2012 12:39:55 GMT
Rhodrigo
I am presuming that you are going to put just 2+ inches vermecrete directly on the dome?. That's not a lot of insulation which will mean that you will need to burn more wood than normal to keep an ambient temperature. The vermecrete layer will form a hard crust, but won't be smooth enough to take paint (not to make it watertight anyway).....this is uncharted territory for me.....but here's what I'd do......I would tack a 1" batten to the sides (and back if you can) giving you the extra space needed for a waterproof render coat......or even better buy 2 bags of K-rend (about £8 each? from your local "Sheffield insulation" outlet.....find their website and it will give your nearest outlet)......this k-rend is waterproof and comes in many colours.
You can remove the batten once the render is set.......
I would guess that 40-50% of people don't calculate the thickness of wall, blanket and insulation layer ...X 2, so your not on your own in finding that you are pushed for space on the insulation layers. Hope you get a bit more feedback from the guys.......and if in doubt.....keep shoutin
Terry
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Post by rhodrigo27 on Jul 31, 2012 13:56:00 GMT
Terry,
The 2 inches is on top of the 25mm blanket insulation, then 2 + inches of vermecrete and then a render. I will have extra space now due to adding the king span Round the outside of the slab. Might add something more solid above the kingspan like you have suggested.
Thanks again
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Post by rhodrigo27 on Aug 4, 2012 9:57:39 GMT
Was just planning on a quick update before commencing work on it today but I was greeted by this scene on arrival ! lovely summer!! But here is what I managed to get done on Friday evening Showing ther first 2 courses and planning of the arch Third course using tool, note the bricks we're not over lapping so I actually started again, starting with a half brik to offset the bricks. View from the back with 3rd course on and showing the arch from behind Will hopefully get a second marquee up today and can get back on it!!!
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Post by cannyfradock on Aug 4, 2012 14:10:57 GMT
Rhodriga At least you had the foresight to cover the dome and put up a gazebo. As ugly as the polythene sheet looks...the photo of your garden in the rain paints a pretty picture. Couple of points that may help you....... Normally a shallower arch is used which generally helps with dome arch transition. The correct method is to cut the rear of the arch bricks....and cut angled bricks of the dome courses where they meet the arch. If you find that the dome bricks are not meeting the arch when making the dome arch transition, you can start elongating the perfect circle of the dome to a more pear shaped circle in order to make that transition work. Most people only ever build ONE oven, so it's difficult sometimes to get all these pieces of a Pompeii build to come together just right. I have learned a lot from previous builds and found that ordering a few 1" fire-bricks along with my normal order from Liam sometimes helps with the dome/arch transition... You haven't got to completely do as others have done, but don't be put off if you have to remove a few bricks and re-lay them. We moved from the old forum because visiting guests couldn't see any uploaded pics and links....and other issues, but here is my build..... woodovenukforum.forumup.co.uk/viewtopic.php?t=851&start=20&postdays=0&postorder=asc&highlight=&mforum=woodovenukforum ......you may pick up some tips from my build...and there are many other builds better than mine, with full photo diaries.....but you have to register with the old forum to be able to view them fully. Looking at other peoples builds...in my eyes is the best research.....but still shout out when you have questions..... terry
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Post by rhodrigo27 on Aug 4, 2012 19:47:38 GMT
Just a quick update with some pics to follow tomorrow. I managed to get to 5 courses today, took a lot of planning and brick cutting with my circular saw and diamond blade. Hopefully tomorrow I can top out,,,
Terry, thanks for that advice. I did spend a lot of the reading others experiences but there is nothing like getting stuck in!! I like what you did with the half bricks and will keep that in mind tomo as I face that transition. I out up a second marquee for me to work under that gave me dry space to work today. Will update and give my story tomo!!!!!
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Post by rhodrigo27 on Aug 31, 2012 16:49:15 GMT
Hi all, I have topped out, going to post some pics below but here is an update, I took down the arch after reading Terry's advice, I re planned and cut the rear of the brick arch to help the arch dome transition, I struggled with the top few courses and took a long time with it, in the end I bodged the top and layer 3 keystone in a mini arch and then used off cuts to act as secondary ish key stones. Building the front entrance arch at the minute and hope to get my insulation and vermecrete on over the weekend, procuring a chimney at the moment . Cheers
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Post by rhodrigo27 on Aug 31, 2012 16:53:50 GMT
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