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Materials advice - my shopping list (UK)

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  • Materials advice - my shopping list (UK)

    Hello all,

    First of all it would be remiss of me not to say thanks to for your many inspirational build diaries/ galleries that have already and will continue to be immensely useful as this project kicks off in earnest. There are some absolutely sensational builds out there, and if I can even manage to get something half as polished as many of you out there, I will consider myself a lucky guy!

    Now, as I currently stand I have a hole in the ground, rebar tied, ready to mix and pour concrete next week (exciting step 1). Step 2 will be building the structure to hold my oven and adjacent workspace.

    In anticipation for Step 3 (the oven itself) I’m just trying to get my materials in place and i'm looking for some advice and for some of the resident professionals on the forum to check my calculations before pressing the purchase button.


    I’m building a Pompeii style oven with a 38” cooking floor.

    My intention is to lay the first course onto the cooking floor, which as far as I can tell appears to be the favoured option of folks on the forum, even though it does look a little easier to me to lay a soldier course that buts up against the side of the cooking floor…..but I’m a newbie and so keen to go with the consensus.

    That aside, I think my materials list needs to look a little like this:

    225 x 42GD firebricks (230 x 114 x 64mm). This is approximate but I think should give me a bit of margin for error.

    2 x LBP HT Blanket 1200GD 7.32M – 610 x 25mm (I think that this should be enough for me to give 3 inches of insulation for a dome of this size)

    3 x Calcium Silicate 1000GD – 1000 x 500 x 75mm (which I think (?) should be enough to cut so that it goes under the entire 110cm wide dome plus the landing area, offering 3 inches of base beneath the brick floor)

    1 x chicken wire 300mm x 13mm hexagonal x 6M

    Now the bits that I’m not sure about are the various bits and pieces for holding all of the bricks together and covering the dome exterior, in sufficiently weatherproof fashion.

    Vitcas (https://shop.vitcas.com/products/hea...s-cements.html) sells a range of products in the UK, all helpfully labelled quite similarly, and to a complete novice seem to be doing very similar things! I can’t quite tell which product should be used for each part of the job.

    I’ve also been looking more actively at Kilnlinings (https://www.kilnlinings.co.uk/Kiln-L...ctory-Castable) who are a little bit more local to me and likely to be the place I purchase the rest of my materials from. I dropped them an email to ask for advice and they helpfully responded as follows:

    Cement
    [Most customers purchase KL-WASC (https://www.kilnlinings.co.uk/Kiln-L...y-Mortars/WASC) . Its very heat resistant though should only be used in 3-5mm thickness max. 1 tub covers approx. 75 brick joints at this thickness of application It also needs to see approx. 300 degrees Celsius right through the joint to make it fully set. So if used on the outside of the brick work it may not fully set without seeing this heat].

    This sounds straight forward enough to me – I would use this to bond all of the bricks to each other and will probably need about 3 tubs overall to finish the build (maybe a 4th tub just to be safe). I had expected that the act of building the dome, getting the bonds just right would result in me making a bit of a mess and as such, a fair amount of this cement ending up on the outside of the dome – not for functional reasons but rather just because I’m likely to be a messy novice. And so, the comment about needing the 300 degrees Celsius to set causes me to question whether this is the best product for the job.

    I’d appreciate views from all on that point.

    Now, after I’ve (hopefully) constructed the dome, I’ll be putting my blankets on, followed by chicken wire. I’ve also been advised to put aluminium foil on (just before the wire) because the foil stops the blanket absorbing the moisture from the final render. This is crucial as if the blanket gets wet it won’t work as it should. In addition the castable render would then crack as it hasn’t the water content it needs.

    Does this sound right?

    Final render

    The final advice I have been given is that…

    [Then a final render is applied. Usually KL-LWIC insulation castable https://www.kilnlinings.co.uk/Kiln-L...stable/L-W-I-C is the castable of choice 6-8 bags for your size oven is the norm. Finally people then brick around the dome or finish it as they wish to ensure its as weather resistant as possible. As the refractory castable is technically a heat resistant concrete it does require protection against the elements and is susceptible to freezing temperatures especially].

    Again, this makes sense. The bit that has caused me to think a little is that final point about elemental protection. At this point, I hadn’t thought too far ahead when it comes to final finish. My assumption was that I might cover with those small hexagonal tiles that I’ve seen people use so well, or maybe a mosaic of some description. That said, I wasn’t necessarily thinking I would do this decorative bit straight away and that I’d have some time to think about it and could figure it out in due course. So, I’m slightly concerned about this comment that it needs protection against the elements.

    I suppose what I’m asking is this – am I overthinking it? Do the two products I have included links for sound like the right ones and are they similar to what you yourself have used? Overall, just buying the suggested amounts of cement/ castable refractory will cost around 600 (about a third of the overall build cost), so I just want to make sure that I don’t make a rookie purchasing decision.


    I appreciate any and all guidance that you may have to offer on the matter

    Oh – and the keen eyed amongst you may have noticed that I haven’t included the chimney on the shopping list……this is a conscious delayed decision, I’ll get this at a slightly later stage once I’m settled on my roofing design. All I can say for now is that I do currently expect to construct a roof, and so will have a fairly tall stainless steel chimney that goes through it.

    Thanks

    Alex
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