Dannos Limey Build (Suffolk UK)

[Bookemdanno]

Re: Dannos Limey Build (Suffolk UK)

I used an initial layer of 20mm Ceramic Blanket which i had from an old kiln, then a layer of high temperature mineral wool which is Rockwool Fire Barrier. A mineral wool based blanket roll to provide a fire stop of 30-60 minutes in roof voids, etc. The temperature rating (up to 600c continuous and 1000c peak once) of the Fire Barrier is much closer to what is expected at the brick face, hence the layer of Ceramic Blanket first. I was told that the Rockwool has better insulation properties than CB, but the downside is its lesser tolerance of heat. CB is much more dense and rigid material also, with the Rockwool more like sheeps wool.
My decisions were also based on the fact that my oven had budget restraints, and the oven dome was not a full firebrick version either. I also wanted to prove that a lower grade of oven could be built, for minimal cost, but still have a high enough performance to give results. Inbetween a Cob Oven and a Firebrick Oven.
If more money were available, i'd not have taken the route i had and if i had a paying customer, they'd be steered towards Firebrick and CB unless they understood the compromises.

[Laurentius]

Re: Dannos Limey Build (Suffolk UK)

Thanks Russell.

My insulation of choice was very soft, much softer than CF, so i'm glad that i decided to set a Vermicrete layer. It'll provide a good intermediate layer for the final render, or Stucco, as you call it over there. I'm just worried about wayward footballs leaving meteor strikes in the dome.

Just read the last posts from you and Nat too. I'm so happy we have the Gulf Stream effect over here, you're talking about the impending snows and the leaves are still green on the trees over here!

Curious, what was your insulation?

[Bookemdanno]

Re: Dannos Limey Build (Suffolk UK)

Thanks Russell.

My insulation of choice was very soft, much softer than CF, so i'm glad that i decided to set a Vermicrete layer. It'll provide a good intermediate layer for the final render, or Stucco, as you call it over there. I'm just worried about wayward footballs leaving meteor strikes in the dome.

Just read the last posts from you and Nat too. I'm so happy we have the Gulf Stream effect over here, you're talking about the impending snows and the leaves are still green on the trees over here!

[UtahBeehiver]

Re: Dannos Limey Build (Suffolk UK)

Hey Bookem,

Nice work on the vcrete. Very smooth and consistent shape, ummm.....has me thinking about adding a vcrete layer over the my CF insulation.

[Bookemdanno]

Re: Dannos Limey Build (Suffolk UK)

Thanks guys, and i'll heed your warnings Gulf. I fired the old gal up too quickly and paid the crack man, so i'll give it a good week at least! Weather is quite damp in the evenings and night over here now, so it's not going to get force dried anyway!

I need a full day on it now anyway to get a render coat on.

[Gulf]

Re: Dannos Limey Build (Suffolk UK)

the feeling of topping out this layer was akin to the keystone going in!

Great job! It is a little extra work dealing with a floating template, but it does feel good knowing that the finished sphere is close to perfect .

Couple of days in the sun now should have it ready for a final render coat.

You might want to give the vcrete a little longer than that to cure. Also, like any other concrete, keeping it covered for a day or two and then allowing it to cure in the shade for a week or two will make it stronger. Drying all the water out of this layer will take probably even longer than that. I'm just paying forward the advice that I was given by David S and a host of others to avoid trapping a lot of water inside the render: "Don't rush it"

[Laku]

Re: Dannos Limey Build (Suffolk UK)

Nicely done! Good clean shape.

[Bookemdanno]

Re: Dannos Limey Build (Suffolk UK)

Vermincrete finished!



Couple of days in the sun now should have it ready for a final render coat.

[Bookemdanno]

Re: Dannos Limey Build (Suffolk UK)

Knocked it all back into the trug, and started again the next evening.

A much better mix, and wetting down the primed layer more started to give much better results and a first foundation layer was in.




My darby was working well, holding the Vermicrete against the insulation whilst it could be tamped lightly in place with the edge of a gauging trowel.
It also followed the shape i wanted for the dome, with the rotating profile really only a guide to verify the shape. I was expecting it more to become a scraper.
As you rise up the dome, the radius decreases so the curved darby becomes more of a tool just to hold back Vermilanches, and keeps thing tidy and faster.


I topped out the Vermicrete layer last night (4/10/12) but the weather has closed in with wind blown rain, so i wrapped it all up in plastic. No finished photos yet, but the feeling of topping out this layer was akin to the keystone going in!

Thanks Guys n Gals!

[Bookemdanno]

Re: Dannos Limey Build (Suffolk UK)

After getting fed up with the ever decreasing amounts of evening time, the Gazebo has gone back up and a 500w Halogen lamp has been rigged up.

I felt a rotating profile would help me get the oven back into shape, along with a curved trowel/darby. Out with the Jigsaw once more!




Then started to work with "Satans Oatmeal"...

started out ok...

got too cocky and built it up too quickly for the too dry mix...

collapsed.

[Bookemdanno]

Re: Dannos Limey Build (Suffolk UK)

Next layer of Rockwool. Very flexible considering that the chicken wire is stitched to it. It sagged a bit in places, but i'll fix that with Vermicrete.




I cut back the wire, removed a dart, and then stitched the wire back together, pulling i tight. It looks like it'll trap more air than Ceramic Blanket, thus being a better insulator, but it cannot tolerate the high heat that Ceramics can, and the upper heat tolerance is a lot closer to what these ovens can run at full chat. Hence my first layer.

I primed the mineral wool with a slurry of NHL2 to act as a intermediate layer and to create a crust, along with a level of suction for the Vermicrete layer.

[Bookemdanno]

Re: Dannos Limey Build (Suffolk UK)

and now you're right up to speed...



20mm Ceramic Blanket as first layer of insulation, which was recycled from a Kiln, along with the Vermiculite Bricks under the hearth. I just used up some foil tape i had left over from an insulation job to hold things in place for now.
All now back under plastic until the next mineral fibre layer.

[Bookemdanno]

Re: Dannos Limey Build (Suffolk UK)

And heres the chimney and outer views...





Chimney is secured within the brick pocket with "Mortarlite" at the moment.

[Bookemdanno]

Re: Dannos Limey Build (Suffolk UK)

Vent now complete...





As i wanted to seal the joint but retain a level of Insulation and strength to support the vent bricks the joint between the oven and chimney arches was filled with a fine Hoticultural Vermiculite 1-5mm grains, and Hydraulic Lime to form "Mortarlite" or "Vermtar". I also raked out many of the cracks, and repointed whilst i was in the area. Hence the odd stained joint. I figured that this'll end up all black from soot over time anyway!

[Bookemdanno]

Re: Dannos Limey Build (Suffolk UK)

Hey Russell, thanks for stopping by! Good luck with your final push for the line!

Can anyone elso who's popping in perhaps give an idea, in hours, as to how long it takes to get the blankies, Vermi, and final render coats on please?

Thanks!