Sheffield build

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

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

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

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

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!!!

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!!!!!