low cost wfo build

[Bookemdanno]

Re: low cost wfo build

Hi Keith, i've been on holiday.

I didn't use fireclay or cement, as i wanted a more traditional approach.
I used a simple Hyraulic Lime mortar of 1 part NHL2: 1 part washed soft sand: 1 part washed sharp sand.
I contacted a few lime mortar artisans and a local guy to me who built a pottery kiln from red brick and lime mortar, and all said that i should be fine. The old ovens were built this way!

I only had an issue with the Lime Render being too "young" to handle such a harsh winter for the UK and its popped off. So, that's a job to repair soon, along with a revised chimney. I'm looking forward to more oven work!!

Good luck with your build.

p.s. if you wanted fine joints internally then a fine sand alone would suffice, then prop the outer edge with a tile or piece of timber. Once the joint has firmed up, you could point up the outer, larger joint, with a sharp sand mix.

Many have also foregone the fireclay and to my knowledge have been fine.

The more irregular the grains of sand, the stronger the mortar, but needs a thicker bed.

Good luck with your build.

[kstronach]

Re: low cost wfo build

thanks guys for the input i'm starting a build thread over in pompeii oven construction. hopefully you guys will follow it and add your wisdom!!

[david s]

Re: low cost wfo build

Aren't all metal garbage bins galvanized? Using a 44 gallon ungalvanized drum would be better.

[bobnealy]

Re: low cost wfo build

Unfortunately, burning hot-dipped galvanized coatings is also very toxic.

They say make sure you get an ungalvanized I still do not think this is a good idea.

[Tscarborough]

Re: low cost wfo build

Unfortunately, burning hot-dipped galvanized coatings is also very toxic.

[bobnealy]

Re: low cost wfo build

now this is cheap way to go
Garbage Can Pizza Oven SamanthaMenzies.com

[kstronach]

Re: low cost wfo build

hey danno,

hows the oven doing? you had it lit recently? so tomorrows the big day for me finally making a start on the oven!! hoping to get the blockwork up in the morning for the stand, i'll start a build thread and post pics as i go so hopefully people can chip in with advice throughout the project!!

just a quick question if i may? what mix did you use for the dome construction? did you use fireclay? i was thinking something along the lines of 6,1,1. 6 silica sand, 1 lime, 1 cement. is that similar to what you used? also thought about adding 1 sharp sand in for a bit of extra strength.

keith

[Bookemdanno]

Re: low cost wfo build

Rockwool is very soft, so i'd probably say it'd be best to go 2" Ceramic Blanket, then 3"-4" Vermicrete, then the render. The Vermicrete will insulate well, not as well as the Rockwool, but provides a really good intermediate layer and base for the Render.
Render over Rockwool would be tricky to achieve and could be susceptible to damage easier as it'd be more of an eggshell, so you'd possibly need a good 2" of render.
My angled approach was a preference, but i wish i'd made a circular one in reality!
I'll have a measure up at the weekend, and let you know my ovens dimensions in relation to the pad size.
Catch you later.

[kstronach]

Re: low cost wfo build

cheers for the tip on freecycle!! already found some flags not to far away from me!!
in your opinion how critical do you think the vermicrete layer is over the rockwool? do you think it would be possible to render straight on to the rockwool and the oven still perform well? just i think i am quite tight for space and was hoping to get my oven on to a 4' by 6' pad (four 2' by 3' flags) that allows me 32" internal size and allowing for all sides 9" brickwork 2" thermal blanket 4" rockwool and 2x coat of render which brings me to very nearly 48" or 4' in width!! does setting your base at 45 degrees like you have allow for better space usage or was that just a personal preference? i'm going to get out in the garden this weekend anyway with the tape measure and have a good measure up if it ever stops raining!!!

[UtahBeehiver]

Re: low cost wfo build

Keith,

I see you are in good hands with Bookem...............good luck with the build and send pictures.

[Bookemdanno]

Re: low cost wfo build

Thanks Keith!
I set a concrete lintel diagonally across the 4" blockwork parallel to the front opening, and then set 2" 3'x2' Council Type paving slabs over. The front arch supports the leading edge of the slabs. Then an insulating layer over the slabs of 4" Thermolites, laid on the side. I can say that underside of the slabs is barely warm to the touch, even on a full Hell-firing!
I adjusted the diameter slightly to suit my heater bricks and quarry tile hearth, along with the first course. Lots of full scale sketches helped here, but i'm pretty close to a 90.
Your dome height should be half the diameter for a Pompeii. Look up the "indespensible tool" on here. It works perfectly, but worked out too slow for me and the higher brick courses. Hence my wooden form.
Keep a keen eye on Ebay and sign up to Freecycle if you're on the look out for materials. Its amazing what comes up!
I see you're also on the UK forum too!

[kstronach]

Re: low cost wfo build

hi danno,

thanks for the reply!
just had a good read through your build thread, nice work!! that is pretty much what i have in mind minus the awsome bbq area and surrounding features! good to hear the red clays are working too that gives me some piece of mind!!
probably no photos till in the new year now although you never know i may get the footing in and the blockwork base!! did you cast a slab or something, tied in with re-bar inside your block work to bed your concrete flags onto? also is your oven 36" internal? how high is your dome internally?

again really nice work! makes me even more eager to start mine!!

keith

[Bookemdanno]

Re: low cost wfo build

Hi there!

I've got Victorian full clay reds for the dome of my oven! Storage heater bricks in the floor. All free, due to budget restraints too. Stay away from dusty very soft reds though.
My digital thermometer tops out at 550c and it can get there after 45minutes at the top of the dome, with 450c+ at the floor. You can cook in it for 2 days after easily on the residual heat.
Insulation is 1" Ceramic Fibre, 2" Rockwool Fire Blanket, 2-3" Vermicrete and Lime Render over. Its not had much use over a prolonged period as its inly just finished, but there is no damage internally yet.
Good luck with the build! Keep the photos coming!

[david s]

Re: low cost wfo build

Plenty of folk have built ovens with solid reds. The problem is that you have no way of telling if they're suitable or not. The composition of the bricks will vary enormously depending where the clay has been sourced. They are not designed for use with fire, although on the other hand they may also be perfectly adequate. If you got them cheap or free, then if it were me, I'd be inclined to use them anyway. Might be advisable to use firebricks for the floor though.

[kstronach]

Re: low cost wfo build

hi david,
i am starting to think that casting the dome isn't the way forward seems like more people would have attempted it if it was a cheaper and feasable option but no one seems to have gone that way so maybe that should tell me something!!

since posting on here i have been able to source some old red clay solid bricks i could build my dome with would these work ok? how would they compete temprature wise compared to firebrick, if they were insulated well after i built the dome? has anyone built an oven with these? before we had firebricks these must have been the norm for hundreds of years right?

keith