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-   -   Keep it simple - stupid! (http://www.fornobravo.com/forum/f6/keep-simple-stupid-6190.html)

Nev Grady 02-26-2009 10:22 AM

Keep it simple - stupid!
 
I'm at the earliest of the planning part of building a Pompeii 42" oven at our holiday home in the English Lake District. Even though it seems to rain there incessantly, I think we'll get a lot of fun and satisfaction out of it!

I've read lots of posts on this excellent forum about the whole process of the build and, in general, everybody says how hard the work is. But does it need to be so hard? Yes, the foundation slab is necessary to support the weight of the oven and supporting brickwork, but is it necessary to have such a massive block of reinforced concrete for the hearth? My idea is to build the foundation and hearth supporting walls as recommended. Instead of using a poured, reinforced concrete hearth, with a layer of Vermiculite cement insulation under the oven floor, what's wrong with using 75mm thick concrete paving slabs with a layer of THERMALITE building blocks as the insulation layer? This should save an lot of time and hard work.

If I'm being stupid please feel free to tell me!

Frances 02-28-2009 09:34 AM

Re: Keep it simple - stupid!
 
Hi Nev!

The poured reinforced concrete slab (and the foundation for that matter) is there because your oven will end up weighing a ton - quite literally. I wouldn't trust that to paving slabs. In addition, if the slab (foundation or hearth) shifts even a little bit, the oven will probably crack (ask Dave).

Themalite, is that an aerated concrete product? There are a couple of discussions on using something like that for insulation, so maybe you could do a search. Carl used something like that somewhere in his build. I think the general verdict was, it insulates well enough, but can get brittle after going through lots of heating/cooling cycles. So again, maybe not a good idea under the oven.

Nev Grady 02-28-2009 11:17 PM

Thermalite and paving slabs.
 
Thanks Frances! My idea of the paving slabs was probably a pie in the sky (or maybe even the oven!). Just wanted to save myself some work!

I'll do as you recommend and research further the Thermalite question.

David Reekie 03-04-2009 12:12 PM

Re: Keep it simple - stupid!
 
Well - I'm in the middle of a build doing just what you thought of - using paving slabs as the hearth base, so I'll be able to let you know how / whether it works very soon! I have mounted them on a couple of concrete lintels though - very quick, very easy, and ought to be plenty strong enough.

I very nearly also went for the aerated concrete blocks for insulation, as you suggest, but didn't for a variety of reasons.

I haven't got any photos yet - did most of the work over the last couple of weekends when my wife was away with the camera. When I get some I'm planning to write up my design and the rationale for it, to share wih this group.

Just as a few snippets for now:

- I also wanted to keep it simple. I like efficiency.
- I had very restricted space and needed to keep it fairly small.
- Small is in some ways a disadvantage (see all the posts here advising people to go as large as possible) so I wanted to take every opportunity to gain advantages too when I could. The main advantage was to scale down the engineering of the whole thing (hence the slabs) and hopefully to speed up heat-up times.

Of course, the big other thing to consider is that building it is supposed to be part of the fun - so extra building work = more fun not less, to a certain degree!



dave

ross 03-04-2009 12:30 PM

Re: Keep it simple - stupid!
 
thats what I did....made sure i had a nice deep vermiculite insulation over the top...didnt even have a lintel just build up building blocks within my brick work
made sure they were compact and very level


All is fine see my album / pic is at

http://www.fornobravo.com/forum/memb...-dscf3105.html


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