Pete C's build - one of the Leeds crew

[petec]

Hi All,

Well I've made a start on my build - I'm hedging my bets as to whether it will be a brick build or clay/cob, but most likely a cobber i think. I think a brick oven might be on the horizon later when I get more experience.

Inspired by the Builds from the North threads I'm going for a similar thing - full plinth and base with storage underneath, together with a circular brick skirt and clay/cob dome. I plan to have a brick arch entrance from the word go.

Last week I dug out my foundations with a 1.5m square hole - only to have a full week of heavy rain and now a second small pond in my garden ! I have therefore been reading a lot and planning my materials sources etc.
But things got better today as I drove past a skip and saw a load of red clay bricks sitting there without a future.....
Turns out when I mentioned it to my wife its one of her colleagues houses and they are renovating. A quick phone call later and we were given the go-ahead to raid the skip for anything we could use.
So we just got back with about 80 nice 1960's red clay brocks that will make a lovely skirt for the dome, and a nice arch to boot !!

So now to source my firebricks - I could do with advice on which size is most popular - I was bewildered by the choice and variation on the kilnlinings website and now I'm confused as to what to buy. Help !

Next I plan on getting the concrete base sorted when the weather improves a bit.
I'll go looking for materials this weekend.

This is fun.
Cheers all
PeteC

[bladesman]

Good luck - if t ever stops raining!!

[surfingspider]

I think I went for these Fire bricks 42GD - 230 x 114 x 76mm kilnlinings.co.uk/fire-bricks-42gd-firebricks/fire-bricks-42gd-230-x-114-x-76mm. They are fairly cheap but thick so will store a lot of heat which is what you want. I also picked them up so saved on shipment which can add a lot if you are only buying a few (my focus didn't like the speed bumps on the way home though!). I did a 27" inside oven diamiter and used about 20. Although I didn't get enough to do my archway in fire brick.

[petec]

thanks very much - I will go with the same stuff i think

cheers
Pete

[petec]

oooh,
one other question if you dont mind

what dimensions did you build your concrete base ?

cheers
Pete

[cannyfradock]

Hello Pete.

Don't forget to add the thickness off the wall of your oven and any insulation and then X 2. My 90 cm internal diameter Pompeii was calculated 900mm plus ....width of brick X 2 = 220mm....plus thermal blanket X 2 = 100mm....plus vermiculite concrete X 2 = 150mm plus waterproof render X 2 = 50mm. This comes to 1.420mm.

The actual footprint of the external brickwork for my oven 6 and a half bricks....1.450mm....this was a bit knapp so next time I will do 7 bricks...= 1.570mm. The base needs to be slightly bigger.

This was calculated on an outer brick wall, and an inner wall to take the slab.

Don;t forget that if you build a clay structure it will need some type of roof. A brick dome just needs waterproof render.....the costs may be similar.

Here's a good photo diary of a build.. picasaweb.google.com/115426447285405371194/WoodFiredOven

For reference here's a few links of my build.....but (not sure) you may have to register with the forum to see the images...

woodovenukforum.forumup.co.uk/viewtopic.php?t=851&mforum=woodovenukforum

www.fornobravo.com/forum/members/cannyfradock-albums-2nd-pompeii-build.html

If you go down the clay route and have problems sourcing clay.....please shout out.......don't forget to give your general area.

Terry

[petec]

Hi again Terry

thanks for the advice.

I'm going for a 27" interior hearth - based on 6 wide x 114mm firebircks from kilnlinings.uk.

I've reading Kiko Denzer's earth oven book , so I'm hoping to do 4" of clay/sand mix, then 4" of insulation from clay / vermiculite. then about an inch of clay slip plaster. I will be adding a small roof - pergola style and probably a tarp for extra cover.

I think a 1.4m sq base will be enough.

Although I'm handy with woodwork, electrics etc , I've never used concrete before so not sure of the easiest way to do the base. I have just been reading up on making bases for sheds etc which looks pretty easy with formwork etc. One question - I dont have any rubble handy for hardcore , but I do have about 7 bags of 1" gravel pebbles leftover from around my patio - can I use these for the hardcore layer if I tamp down firmly before sand , dpc and pour the base ?

Also I couldn't believe just how much concrete a simple 1.4mx1.4m base needs - online calculators said approx 0.25 cu mtrs - seems a hell of a lot - and now I'm thinking I need to hire a cement mixer and buy a lot more sand and ballast mix than I thought. Guidance here very welcome.

Lastly ( for now ! ) - yes - clay sourcing is proving to be a problem. Depsite a clayey soil in our waterlogged garden I no longer have any patches of the garden I can dig up to yield enough clay ( I think I saw somewhere I need about 13 bucketfuls ( ? ) . SO if you have any advice on how/where to get clay then please let me know. I'm in North West Leeds.

Had a trip earlier on today to Jewsons - just to find them closing at midday - bummer ! I should have checked opening times of course !


meanwhile thanks for a great resource .....

Onwards...

Rgds
Pete

[danny]

Hi Pete
I (or rather the builders who were doing my stonework)used concrete lintels to create the bed. No mess and very quick. On top of this went insulation followed by a concrete bed of about 70mm retained by the stone walls that have now continued up.

Cheers.

Ian

[dougclay]

May 12, 2012 15:34:18 GMT petec said:

Lastly ( for now ! ) - yes - clay sourcing is proving to be a problem. Depsite a clayey soil in our waterlogged garden I no longer have any patches of the garden I can dig up to yield enough clay ( I think I saw somewhere I need about 13 bucketfuls ( ? ) . SO if you have any advice on how/where to get clay then please let me know. I'm in North West Leeds.

I dug my sandy clay from under the lawn but I am on the lookout for a different source for some reconstruction/facelift work this year. Look for Puddling Clay, Pond Clay or Engineering Clay... It's used for lining ponds, canals, etc and and will be sold for anywhere between £15 and £50 a ton. I've found a supplier about 30 miles away, but I think I might be a bit small scale for them as they sell by weight where they weigh your truck as you go in and you pay for the additional weight as you drive out... not sure if they do this for family cars too ;-)

[pete123]

My 36" oven is based on Terry's dimensions above. I marked it out today to see what it will look like.

ukwoodfiredovenforum.proboards.com/index.cgi?action=display&board=pompeiiovens&thread=296&page=3

[petec]

More digging today - emptied out the "pond" which had formed in last weeks rain and used a tarp to cover for now.

Ordered my firebricks, vermiculite and fireclay from Liam at Kilnlinings - so no going back now.

Also, have found some really nice smooth clay under my foundation hole - so now need to decide whether to dig a ruddy great hole first to get my clay - or whether to source clay elsewhere and get on with the foundations.

Anyway ..progress ...albeit slow so far .....

Any ideas on how many bucket fulls of clay I need for a 27" interior clay oven ?

Cheers
Pete

[turkey]

May 13, 2012 20:42:57 GMT petec said:

Any ideas on how many bucket fulls of clay I need for a 27" interior clay oven ?

we could try to do it with maths, there is a simple forumla for calulcating the volume of a sphere

v = 4/3 * ð * r3.

The "v" stands for volume and "r" stands for radius of the sphere, ð is pi. (3.14159)

or use an online tool

So what we need to do is work out how thick your walls will be, this thichness we add to the interior 27" to make the large sphere. We then calculate the 27" sphere and take this value from the larger one. Then we half that anwser and thats the volume of the resulting walls. Now we might need to add some for an entereance but its a good guess.

Lets say you walls are 4", there are walls either side so that make the outer diameter 35", so the radius is 17.5"

thats ( 22449in3 - 10306 in3 ) / 2 = 6071 in3

buckets can be in gallons,

1 gallon = 231 cubic inches

5 gallons = (5 x 231) = 1,155 cubic inches

remember that you mix the clay to 2 parts sand I think, so the clay content will be a third of the volume.....

all this thinking is making my head hurt. Hopefully that helps a little, or just points you in a helpful direction.

[cannyfradock]

Pete

Depending on your depth of concrete... .25 cube sounds about right. Mass = x2.2... = .55 tons. Which equates to 22 25kg bags. Working on a 4:2:1 concrete mix (chippings, sand cement).....or what most people do 6:1..(all-in/ballast...cement)..you will need just over 18 bags of all-in and 3 bags of cement. It's cheaper to buy a 1 ton jumbo bag and 4 bags of cement. A cement mixer costs about £25/30 to hire for a day.....well worth the expense.

A cheap source for clay are the turf suppliers. As well as selling turf for your lawn, a lot of them sell clay. My local one sells puddling (the blue sticky stuff....perfect for the first layer....and the brown clay....again, perfect for the second layer if using straw etc.) They both cost £12 a ton. I'd guess you will need at least 1/2 a ton.

Terry

[petec]

Turkey / Terry
many thanks both that's very helpful indeed.

Just picked up my firebricks, vermiculite and fireclay today from kilnlinings after my meetings in Sheffield - very convenient !

Just the concrete, blockwork, mortar, sand etc to get sorted next . I will check out the turf boys locally for clay supplies.

Cheers
Pete

[petec]

OK,

just did some rough calcs ...

taking inner hemishpere from the outer hemisphere to get the ="dome"

For first 4" layer it works out at about 6073cubic inches of mix required.
1 Gallon is circa 277.4 cu inches ( Google )
so 6073 cu inches is approx 22 Gallons.
Assuming Clay to sand ratio is circa 2:1 ( assumes reasonably decent clay quality ) then 1/3rd of the mix needs to be clay and so, about 7.3 Gallons of pure Clay needed.

This is just the inner thermal mass layer - then 4" mix needed for the outer "dome" insulating layer.

For this second layer I'm assuming similar mix - but its bigger radius so ....

hemisphere will be 2/3rds pi x r cubed. ( Half of a sphere )

2/3 x 3.142 x 21.5 cubed ( =9938 ) = 20816 cu inches
minus inner dome of 11228 cu inches
= 9588 cu inches
= 34 gallons approx
div by 3 for mix ratio ..
= 11.5 Gallons

somehow I think with vermiculite mix layer I wont need as much as this - but overall 7.3 + 11.5 gallons = 18.8 gallons of clay .

4 x 5 gallon buckets should cover it.

Let me know if any of that looks wrong !

Cheers
Pete