Using Roofing insulation in pizza oven

[Duckman72]

Hi all
I have made a compromise with Mrs Duckman with regards to the pizza oven. I get to "make" the base and hearth and she has bought a DIY pizza oven kit to build. Everything I've read here tells me that you cannot have enough insulation. The kit came with insulation material but I was going to "double" it by putting additional woolen roofing insulation over dome and under the base. I just got this from Bunnings. Is there a problem with this?

Also is there a problem in sitting the oven straight down on normal concrete base? (Although with a thick layer of insulation between firebricks and concrete)

[cleverdick]

Re: Using Roofing insulation in pizza oven

Pretty sure I read somewhere that Rockwool will not stand the heat of direct contact with the outside of the dome (despite the fact the the manufacturer of my precast recommends it). I would advise calcium silicate blanket on the dome (fixed on with ceramic blanket adhesive), on top of which you can use as much Rockwool as you like.

[GianniFocaccia]

Re: Using Roofing insulation in pizza oven

It's nice that you SWMBO are collaborating on your project. Which oven did she select?

What do you mean 'additional woolen roofing insulation under the base'?

[Duckman72]

Re: Using Roofing insulation in pizza oven

It's nice that you SWMBO are collaborating on your project. Which oven did she select?

What do you mean 'additional woolen roofing insulation under the base'?

Yes we are doing the project together - her specialty is asking...."when will this be finished?" And my specialty is procrastination and over-analysis.

She ended up with the Amalfi Mediterranean family size oven. I had the hearth poured yesterday and will upload some photo's. I'll also show you what I have in mind with the insulation.

Regards
Duckman

[GianniFocaccia]

Re: Using Roofing insulation in pizza oven

Duck,

What a team! Not like my wife and I: she is the most patient, understanding person in the world and my speciality is.... procrastination and over-analysis. Wouldn't want any regrets later on, right?

I looked at the brochure for your oven and it is a nice one. I like the idea of casting it in three main pieces. My daughter is studying abroad this semester at the U of Queensland, and given how expensive things are down under, its amazing that your oven is so affordable. Bunnings?

Looking forward to photos.

John

[vtsteve]

Re: Using Roofing insulation in pizza oven

You need rigid, high-temperature insulation under the oven (and it's a great idea to add extra). If you put the manufacturer's insulation on the dome, and add rock wool over that, you should have no problems. They don't use *sheep* wool for roof insulation in the UK, do they? They sell recycled denim - cotton - batting here for wall insulation...

[GianniFocaccia]

Re: Using Roofing insulation in pizza oven

You need rigid, high-temperature insulation under the oven (and it's a great idea to add extra)

Great point, Steve. The Mediterranean brochure shows a pic of refractory insulation labeled 'floor blanket". This is clearly the wrong product and needs to be rigid, the thicker the better.

[cobblerdave]

Re: Using Roofing insulation in pizza oven

G'day
The Mediterranean is the same oven as sold in Bunnings but made in China. I've seen one built on a 75 mm hebel base. Its owner was more than impressed with how it worked especially the extra level of insulation on the base from the hebel.
Regards Dave
Bunnings, Bunnies, "the big green shed" a hardware store which has taken over the Australian landscape to the point were if you can't find it at bunnings there are no other choices!

[Duckman72]

Re: Using Roofing insulation in pizza oven

Great point, Steve. The Mediterranean brochure shows a pic of refractory insulation labeled 'floor blanket". This is clearly the wrong product and needs to be rigid, the thicker the better.

Thanks for the comments guys.

Sorry I haven't organised the photo's - but yes, the instructions state that you just lay the "floor blanket" on top of the concrete slab hearth and then lay the fire bricks on it. I was going to lay my "roofing insulation" down first followed by the floor blanket. The problem being it feels very "padded". Maybe I should have looked at using hebel blocks.

Cheers
Duckman

[GianniFocaccia]

Re: Using Roofing insulation in pizza oven

Duck,

I know QLD is quite a large place, but other builders have sourced CF boards, IFB and other refractory products in Brissy. Here's a couple of them:

http://www.fornobravo.com/forum/f51/...ane-19275.html

http://www.fornobravo.com/forum/f2/w...bane-3048.html

If these aren't practical, 12-15cm of vermicrete would certainly be a better alternative to blanket. I would save your blanket for over the dome.

[david s]

Re: Using Roofing insulation in pizza oven

Thanks for the comments guys.

Sorry I haven't organised the photo's - but yes, the instructions state that you just lay the "floor blanket" on top of the concrete slab hearth and then lay the fire bricks on it. I was going to lay my "roofing insulation" down first followed by the floor blanket. The problem being it feels very "padded". Maybe I should have looked at using hebel blocks.

Cheers
Duckman

The blanket is fairly dense and does not compress too much and will probably be ok if it is only holding the weight of the floor tiles. Probably not so good in the long term, if it gets wet, or if you are placing heavy cast iron pots in your oven. Roof insulation is way too light to hold anything, unless you can support the floor tiles with some insulating bricks and fill in between them with lightweight insulation.

[Laurentius]

Re: Using Roofing insulation in pizza oven

Roofing insulation doesn't have the same property as thermal insulation and blankets are not for weight bearing, once they are compacted their effectiveness are compromised. If you don't use the correct tools for the jobs, you will pay more in the long term.

[Duckman72]

Re: Using Roofing insulation in pizza oven

Roofing insulation doesn't have the same property as thermal insulation and blankets are not for weight bearing, once they are compacted their effectiveness are compromised. If you don't use the correct tools for the jobs, you will pay more in the long term.

Thankyou for the comments guys. The majority seem to indicate that roof insulation and a fire blanket sitting underneath the firebricks is not really adequate.

Although it wasn't on the plans I am going to look at covering the hearth with hebel blocks (an inch thick). Any taller than this and my pizza oven is getting too high and will start to look out of proportion and strange. It will at least be better than just the fire blanket on top of the bare concrete.

Laurentius' comments about the fire blanket packing down didn't occur to me, however in the owners instructions they say "don't worry if the firebricks sit up at first, they will drop down and fit snuggly after a few firings". What they are actually saying is "the fire blanket will compact with use and as such will be less effective as insulation". Considering we are likely to be at this house for many, many years to come it is worth doing it properly. I'm not going to get a second chance at insulating the floor!

Duckman